diff --git a/.rubocop.yml b/.rubocop.yml
index 0324c412..4193f4b4 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -22,6 +22,8 @@ Metrics/BlockLength:
   Exclude:
     - test/**/*.rb
     - lib/jekyll/configuration.rb
+    - rake/*.rake
+    - jekyll.gemspec
 Metrics/ClassLength:
   Exclude:
     - !ruby/regexp /features\/.*.rb$/
@@ -32,6 +34,8 @@ Metrics/CyclomaticComplexity:
 Metrics/LineLength:
   Exclude:
     - !ruby/regexp /features\/.*.rb/
+    - Rakefile
+    - rake/*.rake
   Max: 90
   Severity: warning
 Metrics/MethodLength:
@@ -44,6 +48,14 @@ Metrics/ParameterLists:
   Max: 4
 Metrics/PerceivedComplexity:
   Max: 8
+Security/MarshalLoad:
+  Exclude:
+    - !ruby/regexp /test\/.*.rb$/
+    - lib/jekyll/regenerator.rb
+Security/YAMLLoad:
+  Exclude:
+    - !ruby/regexp /features\/.*.rb/
+    - !ruby/regexp /test\/.*.rb$/
 Style/Alias:
   Enabled: false
 Style/AlignArray:
@@ -127,5 +139,7 @@ Style/StringLiterals:
   EnforcedStyle: double_quotes
 Style/StringLiteralsInInterpolation:
   EnforcedStyle: double_quotes
+Style/TrailingCommaInLiteral:
+  EnforcedStyleForMultiline: consistent_comma
 Style/UnneededCapitalW:
   Enabled: false
diff --git a/.travis.yml b/.travis.yml
index 6ff7022c..30eb1fc5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,10 +5,10 @@ language: ruby
 sudo: false
 
 rvm:
-  - &ruby1 2.3.1
-  - &ruby2 2.2.5
+  - &ruby1 2.3.3
+  - &ruby2 2.2.6
   - &ruby3 2.1.9
-  - &jruby jruby-9.1.2.0
+  - &jruby jruby-9.1.7.0
 
 matrix:
   include:
diff --git a/Gemfile b/Gemfile
index eda95e5e..7a786c9b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -25,7 +25,7 @@ group :test do
   gem "nokogiri"
   gem "rspec"
   gem "rspec-mocks"
-  gem "rubocop", "~> 0.44.1"
+  gem "rubocop", "~> 0.47"
   gem "test-theme", :path => File.expand_path("./test/fixtures/test-theme", File.dirname(__FILE__))
 
   gem "jruby-openssl" if RUBY_ENGINE == "jruby"
@@ -88,12 +88,12 @@ end
 
 group :site do
   if ENV["PROOF"]
-    gem "html-proofer", "~> 2.0"
+    gem "html-proofer", "~> 3.4"
   end
 
   gem "jekyll-avatar"
   gem "jekyll-mentions"
   gem "jekyll-seo-tag"
   gem "jekyll-sitemap"
-  gem "jemoji", "0.5.1"
+  gem "jemoji"
 end
diff --git a/History.markdown b/History.markdown
index bb10365f..b813f405 100644
--- a/History.markdown
+++ b/History.markdown
@@ -7,6 +7,8 @@
   * Use the current year for the LICENSE of theme (#5712)
   * Update License (#5713)
   * Use Addressable instead of URI to decode (#5726)
+  * throw IncludeTagError if error occurs in included file (#5767)
+  * Write Jekyll::Utils::Exec.run for running shell commands. (#5640)
 
 ### Bug Fixes
 
@@ -14,6 +16,9 @@
   * fix date parsing in file names to be stricter (#5609)
   * Add a module to re-define `ENV["TZ"]` in Windows (#5612)
   * Use each instead of map to actually return nothing (#5668)
+  * include: fix 'no implicit conversion of nil to String' (#5750)
+  * Don't include the theme's includes_path if it is nil. (#5780)
+  * test double slash when input = '/' (#5542)
 
 ### Site Enhancements
 
@@ -33,6 +38,10 @@
   * Docs: move permalinks from documents into config (#5544)
   * Sort gems in `docs/_config.yml` (#5746)
   * [site] Use defaults for docs and news-items (#5744)
+  * Improve collections docs (#5691)
+  * Fix #5730: add gcc and make to the list of requirements (#5731)
+  * Add missing class (#5791)
+  * Improve template docs (#5694)
 
 ### Development Fixes
 
@@ -46,6 +55,13 @@
   * Rubocop: fix Rakefile and gemspec (#5745)
   * Use `assert_nil` (#5725)
   * Sort gems in `jekyll.gemspec` (#5746)
+  * Rubocop: Require consistent comma in multiline literals (#5761)
+  * Bump rubocop (#5765)
+  * New rubocop security checks (#5768)
+  * test/helper: fix flaky plugin path test by removing calls to Dir.chdir without a block (#5779)
+  * Use latest jemoji gem (#5782)
+  * Bump htmlproofer (#5781)
+  * Bump rubies we test against (#5784)
 
 ### Documentation
 
@@ -66,6 +82,12 @@
   * Fix a minor grammatical mistake on themes' document ### -dev (#5748)
   * Correct comments in data_reader.rb (#5621)
   * Add jekyll-pre-commit to plugins list (#5752)
+  * Update quickstart.md (#5758)
+  * Correct minor typo (#5764)
+  * Fix a markdown link to look properly on the web (#5769)
+  * [docs] Info about the help command usage (#5312)
+  * Add missing merge labels for jekyllbot (#5753)
+  * Fix broken links in documentation (#5736)
 
 ## 3.3.1 / 2016-11-14
 
diff --git a/docs/_docs/collections.md b/docs/_docs/collections.md
index 8a1c3a1a..c64abd23 100644
--- a/docs/_docs/collections.md
+++ b/docs/_docs/collections.md
@@ -11,7 +11,13 @@ namespace.
 
 ## Using Collections
 
-### Step 1: Tell Jekyll to read in your collection
+To start using collections, follow these 3 steps:
+
+* [Step 1: Tell Jekyll to read in your collection](#step1)
+* [Step 2: Add your content](#step2)
+* [Step 3: Optionally render your collection's documents into independent files](#step3)
+
+### Step 1: Tell Jekyll to read in your collection {#step1}
 
 Add the following to your site's `_config.yml` file, replacing `my_collection`
 with the name of your collection:
@@ -40,12 +46,12 @@ defaults:
       layout: page
 ```
 
-### Step 2: Add your content
+### Step 2: Add your content {#step2}
 
 Create a corresponding folder (e.g. `<source>/_my_collection`) and add
-documents. YAML Front Matter is read in as data if it exists, and everything
-after it is stuck in the Document's `content` attribute. If no YAML Front
-Matter is provided, Jekyll will not generate the file in your collection.
+documents. YAML front matter is processed if the front matter exists, and everything
+after the front matter is pushed into the document's `content` attribute. If no YAML front
+matter is provided, Jekyll will not generate the file in your collection.
 
 <div class="note info">
   <h5>Be sure to name your directories correctly</h5>
@@ -55,7 +61,7 @@ your <code>_config.yml</code> file, with the addition of the preceding <code>_</
   </p>
 </div>
 
-### Step 3: Optionally render your collection's documents into independent files
+### Step 3: Optionally render your collection's documents into independent files {#step3}
 
 If you'd like Jekyll to create a public-facing, rendered version of each
 document in your collection, set the `output` key to `true` in your collection
@@ -72,19 +78,6 @@ For example, if you have `_my_collection/some_subdir/some_doc.md`,
 it will be rendered using Liquid and the Markdown converter of your
 choice and written out to `<dest>/my_collection/some_subdir/some_doc.html`.
 
-As for posts with [Permalinks](../permalinks/), the document
-URL can be customized by setting `permalink` metadata for the collection:
-
-```yaml
-collections:
-  my_collection:
-    output: true
-    permalink: /awesome/:path/
-```
-
-For example, if you have `_my_collection/some_subdir/some_doc.md`, it will be
-written out to `<dest>/awesome/some_subdir/some_doc/index.html`.
-
 <div class="note info">
   <h5>Don't forget to add YAML for processing</h5>
   <p>
@@ -94,6 +87,21 @@ written out to `<dest>/awesome/some_subdir/some_doc/index.html`.
   </p>
 </div>
 
+## Configuring permalinks for collections {#permalinks}
+
+You can customize the [Permalinks](../permalinks/) for your collection's documents by setting `permalink` property in the collection's configuration as follows:
+
+```yaml
+collections:
+  my_collection:
+    output: true
+    permalink: /awesome/:path/:title.:output_ext
+```
+
+In this example, the collection documents will the have the URL of `awesome` followed by the path to the document and its file extension.
+
+Collections have the following template variables available for permalinks:
+
 <div class="mobile-side-scroller">
 <table>
   <thead>
@@ -148,15 +156,92 @@ written out to `<dest>/awesome/some_subdir/some_doc/index.html`.
 </table>
 </div>
 
+## Permalink examples for collections
+
+Depending on how you declare the permalinks in your configuration file, the permalinks and paths get written differently in the `_site` folder. A few examples will help clarify the options.
+
+Let's say your collection is called `apidocs` with `doc1.md` in your collection. `doc1.md` is grouped inside a folder called `mydocs`. Your project's source directory for the collection looks this:
+
+```
+├── \_apidocs
+│   └── mydocs
+│       └── doc1.md
+```
+
+Based on this scenario, here are a few permalink options.
+
+**Permalink configuration 1**: [Nothing configured] <br/>
+**Output**:
+
+```
+├── apidocs
+│   └── mydocs
+│       └── doc1.html
+```
+
+**Permalink configuration 2**: `/:collection/:path/:title:output_ext`  <br/>
+**Output**:
+
+```
+├── apidocs
+│   └── mydocs
+│       └── doc1.html
+```
+
+**Permalink configuration 3**: No collection permalinks configured, but `pretty` configured for pages/posts. <br/>
+**Output**:
+
+```
+├── apidocs
+│   └── mydocs
+│       └── doc1
+│           └── index.html
+```
+
+**Permalink configuration 4**: `/awesome/:path/:title.html`   <br/>
+**Output**:
+
+```
+├── awesome
+│   └── mydocs
+│       └── doc1.html
+```
+
+**Permalink configuration 5**: `/awesome/:path/:title/`  <br/>
+**Output**:
+
+```
+├── awesome
+│   └── mydocs
+│       └── doc1
+│           └── index.html
+```
+
+**Permalink configuration 6**: `/awesome/:title.html` <br/>
+**Output**:  
+
+```
+├── awesome
+│   └── doc1.html
+```
+
+**Permalink configuration 7**: `:title.html`
+**Output**:
+
+```
+├── doc1.html
+```
+
 ## Liquid Attributes
 
 ### Collections
 
-Each collection is accessible via the `site` Liquid variable. For example, if
+Each collection is accessible as a field on the `site` variable. For example, if
 you want to access the `albums` collection found in `_albums`, you'd use
-`site.albums`. Each collection is itself an array of documents
-(e.g. `site.albums` is an array of documents, much like `site.pages` and
-`site.posts`). See below for how to access attributes of those documents.
+`site.albums`. 
+
+Each collection is itself an array of documents (e.g., `site.albums` is an array of documents, much like `site.pages` and
+`site.posts`). See the table below for how to access attributes of those documents.
 
 The collections are also available under `site.collections`, with the metadata
 you specified in your `_config.yml` (if present) and the following information:
@@ -334,7 +419,7 @@ file, each document has the following attributes:
 
 Attributes from the YAML front matter can be accessed as data anywhere in the
 site. Using the above example for configuring a collection as `site.albums`,
-one might have front matter in an individual file structured as follows (which
+you might have front matter in an individual file structured as follows (which
 must use a supported markup format, and cannot be saved with a `.yaml`
 extension):
 
diff --git a/docs/_docs/deployment-methods.md b/docs/_docs/deployment-methods.md
index 33edec59..79138caa 100644
--- a/docs/_docs/deployment-methods.md
+++ b/docs/_docs/deployment-methods.md
@@ -167,7 +167,7 @@ script executes.
 
 [Rack-Jekyll](https://github.com/adaoraul/rack-jekyll/) is an easy way to deploy your site on any Rack server such as Amazon EC2, Slicehost, Heroku, and so forth. It also can run with [shotgun](https://github.com/rtomayko/shotgun/), [rackup](https://github.com/rack/rack), [mongrel](https://github.com/mongrel/mongrel), [unicorn](https://github.com/defunkt/unicorn/), and [others](https://github.com/adaoraul/rack-jekyll#readme).
 
-Read [this post](http://andycroll.com/ruby/serving-a-jekyll-blog-using-heroku) on how to deploy to Heroku using Rack-Jekyll.
+Read [this post](http://andycroll.com/ruby/serving-a-jekyll-blog-using-heroku/) on how to deploy to Heroku using Rack-Jekyll.
 
 ## Jekyll-Admin for Rails
 
@@ -206,4 +206,3 @@ Setting up Kickster is very easy, just install the gem and you are good to go. M
 [Aerobatic](https://www.aerobatic.com) is an add-on for Bitbucket that brings GitHub Pages style functionality to Bitbucket users. It includes continuous deployment, custom domains with a wildcard SSL cert, CDN, basic auth, and staging branches all in the box.
 
 Automating the build and deployment of a Jekyll site is just as simple as GitHub Pages - push your changes to your repo (excluding the `_site` directory) and within seconds a build will be triggered and your built site deployed to our highly- available, globally distributed hosting service. The build process will even install and execute custom Ruby plugins. See our [Jekyll docs](https://www.aerobatic.com/docs/static-generators#jekyll) for more details.
-
diff --git a/docs/_docs/extras.md b/docs/_docs/extras.md
index 67236e71..87971f74 100644
--- a/docs/_docs/extras.md
+++ b/docs/_docs/extras.md
@@ -14,7 +14,7 @@ Kramdown comes with optional support for LaTeX to PNG rendering via [MathJax](ht
 <script src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML" type="text/javascript"></script>
 ```
 
-For more information about getting started, check out [this excellent blog post](https://web.archive.org/web/20160522225559/http://gastonsanchez.com/opinion/2014/02/16/Mathjax-with-jekyll).
+For more information about getting started, check out [this excellent blog post](http://gastonsanchez.com/visually-enforced/opinion/2014/02/16/Mathjax-with-jekyll/).
 
 ## Alternative Markdown Processors
 
diff --git a/docs/_docs/github-pages.md b/docs/_docs/github-pages.md
index cc738704..875bb0ec 100644
--- a/docs/_docs/github-pages.md
+++ b/docs/_docs/github-pages.md
@@ -11,15 +11,13 @@ content, they’re also a great way to host your Jekyll-powered website for free
 
 Never built a website with GitHub Pages before? [See this marvelous guide by
 Jonathan McGlone to get you up and running](http://jmcglone.com/guides/github-pages/).
-This guide will teach you what you need to know about Git, GitHub, and Jekyll to
-create your very own website on GitHub Pages.
+This guide will teach you what you need to know about Git, GitHub, and Jekyll to create your very own website on GitHub Pages.
 
 ### Project Page URL Structure
 
 Sometimes it's nice to preview your Jekyll site before you push your `gh-pages`
 branch to GitHub. However, the subdirectory-like URL structure GitHub uses for
-Project Pages complicates the proper resolution of URLs. In order to assure your
-site builds properly, use `site.github.url` in your URL's.
+Project Pages complicates the proper resolution of URLs. In order to assure your site builds properly, use `site.github.url` in your URL's.
 
 ```html
 {% raw %}
@@ -90,7 +88,7 @@ gem 'github-pages'
 And be sure to run `bundle update` often.
 
 If you like to install `pages-gem` on Windows you can find instructions by Jens Willmer on
-[how to install github-pages gem on Windows (x64)]("https://jwillmer.de/blog/tutorial/how-to-install-jekyll-and-pages-gem-on-windows-10-x46#github-pages-and-plugins").
+[how to install github-pages gem on Windows (x64)](https://jwillmer.de/blog/tutorial/how-to-install-jekyll-and-pages-gem-on-windows-10-x46#github-pages-and-plugins).
 </div>
 
 <div class="note info">
@@ -138,7 +136,7 @@ looking at right now is contained in the [docs
 folder]({{ site.repository }}/tree/master/docs) of the same repository.
 
 Please refer to GitHub official documentation on
-[user, organization and projets pages](https://help.github.com/articles/user-organization-and-project-pages/)
+[user, organization and project pages](https://help.github.com/articles/user-organization-and-project-pages/)
 to see more detailed examples.
 
 <div class="note warning">
diff --git a/docs/_docs/installation.md b/docs/_docs/installation.md
index bbc35fab..0228a0f8 100644
--- a/docs/_docs/installation.md
+++ b/docs/_docs/installation.md
@@ -13,12 +13,14 @@ encountered and how we might make the process easier.
 Installing Jekyll ought to be straight-forward if all requirements are met.
 Before you start, make sure your system has the following:
 
-- Linux, Unix, or macOS
-- [Ruby](https://www.ruby-lang.org/en/downloads/) (including all development
-  headers, v1.9.3 or above for Jekyll 2 and v2 or above for Jekyll 3)
+- GNU/Linux, Unix, or macOS
+- [Ruby](https://www.ruby-lang.org/en/downloads/) version 2.0 or above, including all development
+  headers
 - [RubyGems](https://rubygems.org/pages/download)
+- [GCC](https://gcc.gnu.org/install/) and [Make](https://www.gnu.org/software/make/) (in case your system doesn't have them installed, which you can check by running `gcc -v` and `make -v` in your system's command line interface)
 
 #### Only required for Jekyll 2 and earlier
+
 - [NodeJS](https://nodejs.org/), or another JavaScript runtime (for CoffeeScript support).
 - [Python 2.7](https://www.python.org/downloads/)
 
diff --git a/docs/_docs/maintaining/merging-a-pull-request.md b/docs/_docs/maintaining/merging-a-pull-request.md
index 9aee4153..ec5599bb 100644
--- a/docs/_docs/maintaining/merging-a-pull-request.md
+++ b/docs/_docs/maintaining/merging-a-pull-request.md
@@ -37,8 +37,10 @@ The categories match the H3's in the history/changelog file, and they are:
 1. Major Enhancements (`+major`) – major updates or breaking changes to the code which necessitate a major version bump (v3 ~> v4)
 2. Minor Enhancements (`+minor`) – minor updates (feature, enhancement) which necessitate a minor version bump (v3.1 ~> v3.2)
 3. Bug Fixes (`+bug`) – corrections to code which do not change or add functionality, which necessitate a patch version bump (v3.1.0 ~> v3.1.1)
-4. Site Enhancements (`+site`) – changes to the source of https://jekyllrb.com, found in `site/`
-5. Development Fixes (`+dev`) – changes which do not affect user-facing functionality or documentation, such as test fixes or bumping internal dependencies
+4. Documentation (`+doc`) - changes to the documentation found in `docs/_docs/`
+5. Site Enhancements (`+site`) – changes to the source of [https://jekyllrb.com](https://jekyllrb.com) found in `docs/`
+6. Development Fixes (`+dev`) – changes which do not affect user-facing functionality or documentation, such as test fixes or bumping internal dependencies
+7. Forward Ports (`+port`) — bug fixes applied to a previous version of Jekyll pulled onto `master`, e.g. cherry-picked commits from `3-1-stable` to `master`
 
 Once @jekyllbot has merged the pull request, you should see three things:
 
diff --git a/docs/_docs/permalinks.md b/docs/_docs/permalinks.md
index bcb39e54..1bd88021 100644
--- a/docs/_docs/permalinks.md
+++ b/docs/_docs/permalinks.md
@@ -327,7 +327,7 @@ As with posts, if you use a permalink style that omits the `.html` file extensio
 
 By default, collections follow a similar structure in the `_site` folder as pages, except that the path is prefaced by the collection name. For example: `collectionname/mypage.html`. For permalink settings that omit the file extension, the path would be `collection_name/mypage/index.html`.
 
-Collections have their own way of setting permalinks. Additionally, collections have unique template variables available available (such as `path` and `output_ext`). See the [Configuring permalinks for collections]( ../collections#permalinks ) in Collections for more information.
+Collections have their own way of setting permalinks. Additionally, collections have unique template variables available available (such as `path` and `output_ext`). See the [Configuring permalinks for collections](../collections/#permalinks) in Collections for more information.
 
 ## Flattening pages in \_site on build
 
diff --git a/docs/_docs/quickstart.md b/docs/_docs/quickstart.md
index 984275f7..50df76cf 100644
--- a/docs/_docs/quickstart.md
+++ b/docs/_docs/quickstart.md
@@ -3,7 +3,8 @@ title: Quick-start guide
 permalink: /docs/quickstart/
 ---
 
-If you already have [Ruby](https://www.ruby-lang.org/en/downloads/) and [RubyGems](https://rubygems.org/pages/download) installed (see Jekyll's [requirements](/docs/installation/#requirements/)), you can create a new Jekyll site by doing the following:
+
+If you already have a full [Ruby](https://www.ruby-lang.org/en/downloads/) development environment with all headers and [RubyGems](https://rubygems.org/pages/download) installed (see Jekyll's [requirements](/docs/installation/#requirements/)), you can create a new Jekyll site by doing the following:
 
 ```sh
 # Install Jekyll and Bundler gems through RubyGems
@@ -21,6 +22,8 @@ If you already have [Ruby](https://www.ruby-lang.org/en/downloads/) and [RubyGem
 # Now browse to http://localhost:4000
 ```
 
+If you encounter any unexpected errors during the above, please refer to the already-mentioned [requirements](/docs/installation/#requirements/) page, as you might be missing development headers or other prerequisites.
+
 ## About Bundler
 
 `gem install jekyll bundler` installs the [jekyll](https://rubygems.org/gems/jekyll/) and [bundler](https://rubygems.org/gems/bundler) gems through [RubyGems](https://rubygems.org/). You need only to install the gems one time &mdash; not every time you create a new Jekyll project. Here are some additional details:
@@ -34,11 +37,14 @@ If you already have [Ruby](https://www.ruby-lang.org/en/downloads/) and [RubyGem
 
 `jekyll new <PATH>` installs a new Jekyll site at the path specified (relative to current directory). In this case, Jekyll will be installed in a directory called `myblog`. Here are some additional details:
 
-* To install the Jekyll site into the directory you're currently in, run `jekyll new .` If the existing directory isn't empty, you can pass the `--force` option with `jekyll new . --force`.  
+* To install the Jekyll site into the directory you're currently in, run `jekyll new .` If the existing directory isn't empty, you can pass the `--force` option with `jekyll new . --force`.
 * `jekyll new` automatically initiates `bundle install` to install the dependencies required. (If you don't want Bundler to install the gems, use `jekyll new myblog --skip-bundle`.)
 * By default, the Jekyll site installed by `jekyll new` uses a gem-based theme called [Minima](https://github.com/jekyll/minima). With [gem-based themes](../themes), some of the directories and files are stored in the theme-gem, hidden from your immediate view.
 * To learn about other parameters you can include with `jekyll new`, type `jekyll new --help`.
 
+When in doubt, use the <code>help</code> command to remind you of all available options and usage, it also works with the <code>new</code>, <code>build</code> and <code>serve</code> subcommands, e.g. <code>jekyll help new</code> or <code>jekyll help build</code>.
+{: .note .info }
+
 ## Next steps
 
 Building a Jekyll site with the default theme is just the first step. The real magic happens when you start creating blog posts, using the front matter to control templates and layouts, and taking advantage of all the awesome configuration options Jekyll makes available.
diff --git a/docs/_docs/templates.md b/docs/_docs/templates.md
index 26bd804a..0d4975d6 100644
--- a/docs/_docs/templates.md
+++ b/docs/_docs/templates.md
@@ -420,56 +420,15 @@ The default is `default`. They are as follows (with what they filter):
 
 ### Includes
 
-If you have small page fragments that you wish to include in multiple places on
-your site, you can use the `include` tag.
+If you have small page snippets that you want to include in multiple places on your site, save the snippets as *include files* and insert them where required, by using the `include` tag:
 
 ```liquid
 {% raw %}{% include footer.html %}{% endraw %}
 ```
 
-Jekyll expects all include files to be placed in an `_includes` directory at the
-root of your source directory. This will embed the contents of
-`<source>/_includes/footer.html` into the calling file.
+Jekyll expects all *include files* to be placed in an `_includes` directory at the root of your source directory. In the above example, this will embed the contents of `_includes/footer.html` into the calling file.
 
-<div class="note">
-  <h5>ProTip™: Use variables as file name</h5>
-  <p>
-
-    The name of the file you wish to embed can be literal (as in the example above),
-    or you can use a variable, using liquid-like variable syntax as in
-    <code>{% raw %}{% include {{my_variable}} %}{% endraw %}</code>.
-
-  </p>
-</div>
-
-You can also pass parameters to an include. Omit the quotation marks to send a variable's value. Liquid curly brackets should not be used here:
-
-```liquid
-{% raw %}{% include footer.html param="value" variable-param=page.variable %}{% endraw %}
-```
-
-These parameters are available via Liquid in the include:
-
-```liquid
-{% raw %}{{ include.param }}{% endraw %}
-```
-
-#### Including files relative to another file
-
-You can also choose to include file fragments relative to the current file:
-
-```liquid
-{% raw %}{% include_relative somedir/footer.html %}{% endraw %}
-```
-
-You won't need to place your included content within the `_includes` directory. Instead,
-the inclusion is specifically relative to the file where the tag is being used. For example,
-if `_posts/2014-09-03-my-file.markdown` uses the `include_relative` tag, the included file
-must be within the `_posts` directory, or one of its subdirectories. You cannot include
-files in other locations.
-
-All the other capabilities of the `include` tag are available to the `include_relative` tag,
-such as using variables.
+For more advanced information on using includes, see [Includes](../includes).
 
 ### Code snippet highlighting
 
@@ -529,64 +488,6 @@ site. If you use `linenos`, you might want to include an additional CSS class
 definition for the `.lineno` class in `syntax.css` to distinguish the line
 numbers from the highlighted code.
 
-### Link
-
-If you want to include a link to a collection's document, a post, a page
-or a file the `link` tag will generate the correct permalink URL for the path
-you specify.
-
-You must include the file extension when using the `link` tag.
-
-```liquid
-{% raw %}
-{{ site.baseurl }}{% link _collection/name-of-document.md %}
-{{ site.baseurl }}{% link _posts/2016-07-26-name-of-post.md %}
-{{ site.baseurl }}{% link news/index.html %}
-{{ site.baseurl }}{% link /assets/files/doc.pdf %}
-{% endraw %}
-```
-
-You can also use this tag to create a link in Markdown as follows:
-
-```liquid
-{% raw %}
-[Link to a document]({{ site.baseurl }}{% link _collection/name-of-document.md %})
-[Link to a post]({{ site.baseurl }}{% link _posts/2016-07-26-name-of-post.md %})
-[Link to a page]({{ site.baseurl }}{% link news/index.html %})
-[Link to a file]({{ site.baseurl }}{% link /assets/files/doc.pdf %})
-{% endraw %}
-```
-
-### Post URL
-
-If you would like to include a link to a post on your site, the `post_url` tag
-will generate the correct permalink URL for the post you specify.
-
-```liquid
-{% raw %}
-{{ site.baseurl }}{% post_url 2010-07-21-name-of-post %}
-{% endraw %}
-```
-
-If you organize your posts in subdirectories, you need to include subdirectory
-path to the post:
-
-```liquid
-{% raw %}
-{{ site.baseurl }}{% post_url /subdir/2010-07-21-name-of-post %}
-{% endraw %}
-```
-
-There is no need to include the file extension when using the `post_url` tag.
-
-You can also use this tag to create a link to a post in Markdown as follows:
-
-```liquid
-{% raw %}
-[Name of Link]({{ site.baseurl }}{% post_url 2010-07-21-name-of-post %})
-{% endraw %}
-```
-
 ### Gist
 
 Use the `gist` tag to easily embed a GitHub Gist onto your site. This works
@@ -608,3 +509,71 @@ You may also optionally specify the filename in the gist to display:
 
 To use the `gist` tag, you'll need to add the
 [jekyll-gist](https://github.com/jekyll/jekyll-gist) gem to your project.
+
+## Links
+
+### Linking to pages {#link}
+
+To link to a post, a page, collection item, or file, the `link` tag will generate the correct permalink URL for the path you specify. For example, if you use the `link` tag to link to `mypage.html`, even if you change your permalink style to include the file extension or omit it, the URL formed by the `link` tag will always be valid.
+
+You must include the file's original extension when using the `link` tag. Here are some examples:
+
+```liquid
+{% raw %}
+{{ site.baseurl }}{% link _collection/name-of-document.md %}
+{{ site.baseurl }}{% link _posts/2016-07-26-name-of-post.md %}
+{{ site.baseurl }}{% link news/index.html %}
+{{ site.baseurl }}{% link /assets/files/doc.pdf %}
+{% endraw %}
+```
+
+You can also use the `link` tag to create a link in Markdown as follows:
+
+```liquid
+{% raw %}
+[Link to a document]({{ site.baseurl }}{% link _collection/name-of-document.md %})
+[Link to a post]({{ site.baseurl }}{% link _posts/2016-07-26-name-of-post.md %})
+[Link to a page]({{ site.baseurl }}{% link news/index.html %})
+[Link to a file]({{ site.baseurl }}{% link /assets/files/doc.pdf %})
+{% endraw %}
+```
+
+(Including `{% raw %}{{ site.baseurl }}{% endraw %}` is optional &mdash; it depends on whether you want to preface the page URL with the `baseurl` value.)
+
+The path to the post, page, or collection is defined as the path relative to the root directory (where your config file is) to the file, not the path from your existing page to the other page.
+
+For example, suppose you're creating a link `page_a.md` (stored in `pages/folder1/folder2`) to `page_b.md` (stored in  `pages/folder1`). Your path in the link would not be `../page_b.html`. Instead, it would be `/pages/folder1/page_b.md`.
+
+If you're unsure of the path, add `{% raw %}{{ page.path }}{% endraw %}` to the page and it will display the path.
+
+One major benefit of using the `link` tag is link validation. If the link doesn't exist, Jekyll won't build your site. This is a good thing, as it will alert you to a broken link so you can fix it (rather than allowing you to build and deploy a site with broken links).
+
+Note you cannot add filters to `link` tags. For example, you cannot append a string using Liquid filters, such as `{% raw %}{% link mypage.html | append: "#section1" %} {% endraw %}`. To link to sections on a page, you will need to use regular HTML or Markdown linking techniques.
+
+### Linking to posts
+
+If you want like to include a link to a post on your site, the `post_url` tag will generate the correct permalink URL for the post you specify.
+
+```liquid
+{% raw %}
+{{ site.baseurl }}{% post_url 2010-07-21-name-of-post %}
+{% endraw %}
+```
+
+If you organize your posts in subdirectories, you need to include subdirectory path to the post:
+
+```liquid
+{% raw %}
+{{ site.baseurl }}{% post_url /subdir/2010-07-21-name-of-post %}
+{% endraw %}
+```
+
+There is no need to include the file extension when using the `post_url` tag.
+
+You can also use this tag to create a link to a post in Markdown as follows:
+
+```liquid
+{% raw %}
+[Name of Link]({{ site.baseurl }}{% post_url 2010-07-21-name-of-post %})
+{% endraw %}
+```
diff --git a/docs/_docs/usage.md b/docs/_docs/usage.md
index c8860373..f4123aed 100644
--- a/docs/_docs/usage.md
+++ b/docs/_docs/usage.md
@@ -96,5 +96,12 @@ $ jekyll build --source _source --destination _deploy
 For more about the possible configuration options, see the
 [configuration](../configuration/) page.
 
+<div class="note info">
+  <h5>Call for help</h5>
+  <p>
+    The <code>help</code> command is always here to remind you of all available options and usage, and also works with the <code>build</code>, <code>serve</code> and <code>new</code> subcommands, e.g <code>jekyll help new</code> or <code>jekyll help build</code>.
+  </p>
+</div>
+
 If you're interested in browsing these docs on-the-go, install the
 `jekyll-docs` gem and run `jekyll docs` in your terminal.
diff --git a/docs/_docs/windows.md b/docs/_docs/windows.md
index 62fb69b4..d3a0fa64 100644
--- a/docs/_docs/windows.md
+++ b/docs/_docs/windows.md
@@ -15,7 +15,8 @@ A quick way to install Jekyll is to follow the [installation instructions by Dav
  2. Install Ruby via Chocolatey: `choco install ruby -y`
  3. Reopen a command prompt and install Jekyll: `gem install jekyll`
 
-Updates in the infrastructure of Ruby may cause SSL errors when attempting to use `gem install` with versions of the RubyGems package older than 2.6. (The RubyGems package installed via the Chocolatey tool is version 2.3) If you have installed an older version, you can update the RubyGems package using the directions [here.][ssl-certificate-update]
+Updates in the infrastructure of Ruby may cause SSL errors when attempting to use `gem install` with versions of the RubyGems package older than 2.6. (The RubyGems package installed via the Chocolatey tool is version 2.3) If you have installed an older version, you can update the RubyGems package using the directions [here][ssl-certificate-update].
+
 [ssl-certificate-update]: http://guides.rubygems.org/ssl-certificate-update/#installing-using-update-packages
 
 For a more conventional way of installing Jekyll you can follow this [complete guide to install Jekyll 3 on Windows by Sverrir Sigmundarson][windows-installjekyll3].
@@ -38,10 +39,10 @@ $ chcp 65001
 
 ## Timezone Management
 
-Since Windows doesn't have a native source of zoneinfo data, the Ruby Interpreter would not understand IANA Timezones and hence using them had the `TZ` environment variable default to UTC/GMT 00:00.  
+Since Windows doesn't have a native source of zoneinfo data, the Ruby Interpreter would not understand IANA Timezones and hence using them had the `TZ` environment variable default to UTC/GMT 00:00.
 Though Windows users could alternatively define their blog's timezone by setting the key to use POSIX format of defining timezones, it wasn't as user-friendly when it came to having the clock altered to changing DST-rules.
 
-Jekyll now uses a rubygem to internally configure Timezone based on established [IANA Timezone Database](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones).  
+Jekyll now uses a rubygem to internally configure Timezone based on established [IANA Timezone Database](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones).
 While 'new' blogs created with Jekyll v3.4 and greater, will have the following added to their 'Gemfile' by default, existing sites *will* have to update their 'Gemfile' (and installed) to enable development on Windows:
 
 ```ruby
diff --git a/features/rendering.feature b/features/rendering.feature
index 5031ef06..fbe9ce57 100644
--- a/features/rendering.feature
+++ b/features/rendering.feature
@@ -12,6 +12,15 @@ Feature: Rendering
     Then  I should get a non-zero exit-status
     And   I should see "Liquid Exception" in the build output
 
+  Scenario: When receiving bad Liquid in included file
+    Given I have a _includes directory
+    And   I have a "_includes/invalid.html" file that contains "{% INVALID %}"
+    And   I have a "index.html" page with layout "simple" that contains "{% include invalid.html %}"
+    And   I have a simple layout that contains "{{ content }}"
+    When  I run jekyll build
+    Then  I should get a non-zero exit-status
+    And   I should see "Liquid Exception.*Unknown tag 'INVALID' in.*_includes/invalid\.html" in the build output
+
   Scenario: Render Liquid and place in layout
     Given I have a "index.html" page with layout "simple" that contains "Hi there, Jekyll {{ jekyll.environment }}!"
     And I have a simple layout that contains "{{ content }}Ahoy, indeed!"
diff --git a/features/support/formatter.rb b/features/support/formatter.rb
index 22237010..79d14664 100644
--- a/features/support/formatter.rb
+++ b/features/support/formatter.rb
@@ -16,7 +16,7 @@ module Jekyll
         :pending   => "\u203D".yellow,
         :undefined => "\u2718".red,
         :passed    => "\u2714".green,
-        :skipped   => "\u203D".blue
+        :skipped   => "\u203D".blue,
       }.freeze
 
       #
diff --git a/features/support/helpers.rb b/features/support/helpers.rb
index 1340808a..06d768fe 100644
--- a/features/support/helpers.rb
+++ b/features/support/helpers.rb
@@ -1,6 +1,5 @@
 require "fileutils"
 require "jekyll"
-require "open3"
 require "time"
 require "safe_yaml/load"
 
@@ -103,26 +102,18 @@ def run_jekyll(args)
 end
 
 #
-
-# rubocop:disable Metrics/AbcSize
 def run_in_shell(*args)
-  i, o, e, p = Open3.popen3(*args)
-  out = o.read.strip
-  err = e.read.strip
+  p, output = Jekyll::Utils::Exec.run(*args)
 
-  [i, o, e].each(&:close)
-
-  File.write(Paths.status_file, p.value.exitstatus)
+  File.write(Paths.status_file, p.exitstatus)
   File.open(Paths.output_file, "wb") do |f|
     f.puts "$ " << args.join(" ")
-    f.puts out
-    f.puts err
-    f.puts "EXIT STATUS: #{p.value.exitstatus}"
+    f.puts output
+    f.puts "EXIT STATUS: #{p.exitstatus}"
   end
 
-  p.value
+  p
 end
-# rubocop:enable Metrics/AbcSize
 
 #
 
@@ -142,7 +133,7 @@ def location(folder, direction)
   end
 
   [before || ".",
-    after || "."]
+    after || ".",]
 end
 
 #
@@ -160,7 +151,7 @@ def seconds_agnostic_datetime(datetime = Time.now)
   [
     Regexp.escape(date),
     "#{time}:\\d{2}",
-    Regexp.escape(zone)
+    Regexp.escape(zone),
   ] \
     .join("\\ ")
 end
diff --git a/lib/jekyll/commands/doctor.rb b/lib/jekyll/commands/doctor.rb
index c7f387df..59004c96 100644
--- a/lib/jekyll/commands/doctor.rb
+++ b/lib/jekyll/commands/doctor.rb
@@ -35,7 +35,7 @@ module Jekyll
             fsnotify_buggy?(site),
             !deprecated_relative_permalinks(site),
             !conflicting_urls(site),
-            !urls_only_differ_by_case(site)
+            !urls_only_differ_by_case(site),
           ].all?
         end
 
diff --git a/lib/jekyll/commands/new.rb b/lib/jekyll/commands/new.rb
index 561ae861..144fddf7 100644
--- a/lib/jekyll/commands/new.rb
+++ b/lib/jekyll/commands/new.rb
@@ -125,23 +125,23 @@ RUBY
         # unless the user opts to generate a blank blog or skip 'bundle install'.
 
         def after_install(path, options = {})
-          Jekyll.logger.info "New jekyll site installed in #{path.cyan}."
-          Jekyll.logger.info "Bundle install skipped." if options["skip-bundle"]
-
           unless options["blank"] || options["skip-bundle"]
             bundle_install path
           end
+
+          Jekyll.logger.info "New jekyll site installed in #{path.cyan}."
+          Jekyll.logger.info "Bundle install skipped." if options["skip-bundle"]
         end
 
         def bundle_install(path)
           Jekyll::External.require_with_graceful_fail "bundler"
           Jekyll.logger.info "Running bundle install in #{path.cyan}..."
           Dir.chdir(path) do
-            if ENV["CI"]
-              system("bundle", "install", "--quiet")
-            else
-              system("bundle", "install")
+            process, output = Jekyll::Utils::Exec.run("bundle", "install")
+            output.to_s.each_line do |line|
+              Jekyll.logger.info("Bundler:".green, line.strip) unless line.to_s.empty?
             end
+            raise SystemExit unless process.success?
           end
         end
       end
diff --git a/lib/jekyll/commands/serve.rb b/lib/jekyll/commands/serve.rb
index e0da4807..16913595 100644
--- a/lib/jekyll/commands/serve.rb
+++ b/lib/jekyll/commands/serve.rb
@@ -10,9 +10,9 @@ module Jekyll
           "ssl_key"            => ["--ssl-key [KEY]", "X.509 (SSL) Private Key."],
           "port"               => ["-P", "--port [PORT]", "Port to listen on"],
           "show_dir_listing"   => ["--show-dir-listing",
-            "Show a directory listing instead of loading your index file."],
+            "Show a directory listing instead of loading your index file.",],
           "skip_initial_build" => ["skip_initial_build", "--skip-initial-build",
-            "Skips the initial site build which occurs before the server is started."]
+            "Skips the initial site build which occurs before the server is started.",],
         }.freeze
 
         #
@@ -88,7 +88,7 @@ module Jekyll
               index.rhtml
               index.cgi
               index.xml
-            )
+            ),
           }
 
           opts[:DirectoryIndex] = [] if opts[:JekyllOptions]["show_dir_listing"]
@@ -116,8 +116,8 @@ module Jekyll
           WEBrick::Config::FileHandler.merge({
             :FancyIndexing     => true,
             :NondisclosureName => [
-              ".ht*", "~*"
-            ]
+              ".ht*", "~*",
+            ],
           })
         end
 
@@ -139,7 +139,7 @@ module Jekyll
             :prefix  => ssl_enabled ? "https" : "http",
             :address => address,
             :port    => port,
-            :baseurl => baseurl ? "#{baseurl}/" : ""
+            :baseurl => baseurl ? "#{baseurl}/" : "",
           })
         end
 
diff --git a/lib/jekyll/commands/serve/servlet.rb b/lib/jekyll/commands/serve/servlet.rb
index d0dd22af..3ae5cf32 100644
--- a/lib/jekyll/commands/serve/servlet.rb
+++ b/lib/jekyll/commands/serve/servlet.rb
@@ -6,7 +6,7 @@ module Jekyll
       class Servlet < WEBrick::HTTPServlet::FileHandler
         DEFAULTS = {
           "Cache-Control" => "private, max-age=0, proxy-revalidate, " \
-            "no-store, no-cache, must-revalidate"
+            "no-store, no-cache, must-revalidate",
         }.freeze
 
         def initialize(server, root, callbacks)
diff --git a/lib/jekyll/configuration.rb b/lib/jekyll/configuration.rb
index 8dc1807d..27e245e4 100644
--- a/lib/jekyll/configuration.rb
+++ b/lib/jekyll/configuration.rb
@@ -58,15 +58,15 @@ module Jekyll
       "defaults"          => [],
 
       "liquid"            => {
-        "error_mode" => "warn"
+        "error_mode" => "warn",
       },
 
       "rdiscount"         => {
-        "extensions" => []
+        "extensions" => [],
       },
 
       "redcarpet"         => {
-        "extensions" => []
+        "extensions" => [],
       },
 
       "kramdown"          => {
@@ -76,8 +76,8 @@ module Jekyll
         "smart_quotes"  => "lsquo,rsquo,ldquo,rdquo",
         "input"         => "GFM",
         "hard_wrap"     => false,
-        "footnote_nr"   => 1
-      }
+        "footnote_nr"   => 1,
+      },
     }.map { |k, v| [k, v.freeze] }].freeze
 
     class << self
diff --git a/lib/jekyll/converters/markdown/kramdown_parser.rb b/lib/jekyll/converters/markdown/kramdown_parser.rb
index dd71c6c1..a7252f1a 100644
--- a/lib/jekyll/converters/markdown/kramdown_parser.rb
+++ b/lib/jekyll/converters/markdown/kramdown_parser.rb
@@ -11,7 +11,7 @@ module Jekyll
           "line_numbers"      => "inline",
           "line_number_start" => 1,
           "tab_width"         => 4,
-          "wrap"              => "div"
+          "wrap"              => "div",
         }.freeze
 
         def initialize(config)
diff --git a/lib/jekyll/converters/markdown/redcarpet_parser.rb b/lib/jekyll/converters/markdown/redcarpet_parser.rb
index b5ec99f5..aa170feb 100644
--- a/lib/jekyll/converters/markdown/redcarpet_parser.rb
+++ b/lib/jekyll/converters/markdown/redcarpet_parser.rb
@@ -21,7 +21,7 @@ class Jekyll::Converters::Markdown::RedcarpetParser
           code,
           {
             :lexer   => lang,
-            :options => { :encoding => "utf-8" }
+            :options => { :encoding => "utf-8" },
           }
         ),
         lang
diff --git a/lib/jekyll/document.rb b/lib/jekyll/document.rb
index ad5884ef..fecd5828 100644
--- a/lib/jekyll/document.rb
+++ b/lib/jekyll/document.rb
@@ -196,7 +196,7 @@ module Jekyll
       @url = URL.new({
         :template     => url_template,
         :placeholders => url_placeholders,
-        :permalink    => permalink
+        :permalink    => permalink,
       }).to_s
     end
 
@@ -469,14 +469,14 @@ module Jekyll
           "category",
           "categories"
         )
-        ).map(&:to_s).flatten.uniq
+        ).map(&:to_s).flatten.uniq,
       })
     end
 
     private
     def populate_tags
       merge_data!({
-        "tags" => Utils.pluralized_array_from_hash(data, "tag", "tags").flatten
+        "tags" => Utils.pluralized_array_from_hash(data, "tag", "tags").flatten,
       })
     end
 
diff --git a/lib/jekyll/drops/jekyll_drop.rb b/lib/jekyll/drops/jekyll_drop.rb
index 50163d74..e3d2eb38 100644
--- a/lib/jekyll/drops/jekyll_drop.rb
+++ b/lib/jekyll/drops/jekyll_drop.rb
@@ -20,7 +20,7 @@ module Jekyll
       def to_h
         @to_h ||= {
           "version"     => version,
-          "environment" => environment
+          "environment" => environment,
         }
       end
 
diff --git a/lib/jekyll/entry_filter.rb b/lib/jekyll/entry_filter.rb
index 5f3431d8..e4187d42 100644
--- a/lib/jekyll/entry_filter.rb
+++ b/lib/jekyll/entry_filter.rb
@@ -2,7 +2,7 @@ module Jekyll
   class EntryFilter
     attr_reader :site
     SPECIAL_LEADING_CHARACTERS = [
-      ".", "_", "#", "~"
+      ".", "_", "#", "~",
     ].freeze
 
     def initialize(site, base_directory = nil)
diff --git a/lib/jekyll/filters/grouping_filters.rb b/lib/jekyll/filters/grouping_filters.rb
index a16901d9..e7a904a4 100644
--- a/lib/jekyll/filters/grouping_filters.rb
+++ b/lib/jekyll/filters/grouping_filters.rb
@@ -54,7 +54,7 @@ module Jekyll
           array << {
             "name"  => item.first,
             "items" => item.last,
-            "size"  => item.last.size
+            "size"  => item.last.size,
           }
         end
       end
diff --git a/lib/jekyll/hooks.rb b/lib/jekyll/hooks.rb
index 9083b27a..5f21b5f6 100644
--- a/lib/jekyll/hooks.rb
+++ b/lib/jekyll/hooks.rb
@@ -6,7 +6,7 @@ module Jekyll
     PRIORITY_MAP = {
       :low    => 10,
       :normal => 20,
-      :high   => 30
+      :high   => 30,
     }.freeze
 
     # initial empty hooks
@@ -17,26 +17,26 @@ module Jekyll
         :post_read   => [],
         :pre_render  => [],
         :post_render => [],
-        :post_write  => []
+        :post_write  => [],
       },
       :pages     => {
         :post_init   => [],
         :pre_render  => [],
         :post_render => [],
-        :post_write  => []
+        :post_write  => [],
       },
       :posts     => {
         :post_init   => [],
         :pre_render  => [],
         :post_render => [],
-        :post_write  => []
+        :post_write  => [],
       },
       :documents => {
         :post_init   => [],
         :pre_render  => [],
         :post_render => [],
-        :post_write  => []
-      }
+        :post_write  => [],
+      },
     }
 
     # map of all hooks and their priorities
@@ -64,7 +64,7 @@ module Jekyll
         :post_init   => [],
         :pre_render  => [],
         :post_render => [],
-        :post_write  => []
+        :post_write  => [],
       }
 
       unless @registry[owner][event]
diff --git a/lib/jekyll/log_adapter.rb b/lib/jekyll/log_adapter.rb
index 70173b91..965f3295 100644
--- a/lib/jekyll/log_adapter.rb
+++ b/lib/jekyll/log_adapter.rb
@@ -6,7 +6,7 @@ module Jekyll
       :debug => ::Logger::DEBUG,
       :info  => ::Logger::INFO,
       :warn  => ::Logger::WARN,
-      :error => ::Logger::ERROR
+      :error => ::Logger::ERROR,
     }.freeze
 
     # Public: Create a new instance of a log writer
diff --git a/lib/jekyll/page.rb b/lib/jekyll/page.rb
index 7619966d..324a867d 100644
--- a/lib/jekyll/page.rb
+++ b/lib/jekyll/page.rb
@@ -98,7 +98,7 @@ module Jekyll
       @url ||= URL.new({
         :template     => template,
         :placeholders => url_placeholders,
-        :permalink    => permalink
+        :permalink    => permalink,
       }).to_s
     end
 
@@ -108,7 +108,7 @@ module Jekyll
       {
         :path       => @dir,
         :basename   => basename,
-        :output_ext => output_ext
+        :output_ext => output_ext,
       }
     end
 
diff --git a/lib/jekyll/plugin.rb b/lib/jekyll/plugin.rb
index bcc1bf7e..4680be32 100644
--- a/lib/jekyll/plugin.rb
+++ b/lib/jekyll/plugin.rb
@@ -5,7 +5,7 @@ module Jekyll
       :highest => 100,
       :lowest  => -100,
       :normal  => 0,
-      :high    => 10
+      :high    => 10,
     }.freeze
 
     #
diff --git a/lib/jekyll/readers/data_reader.rb b/lib/jekyll/readers/data_reader.rb
index 6744ae05..1083d62b 100644
--- a/lib/jekyll/readers/data_reader.rb
+++ b/lib/jekyll/readers/data_reader.rb
@@ -54,7 +54,7 @@ module Jekyll
       when ".csv"
         CSV.read(path, {
           :headers  => true,
-          :encoding => site.config["encoding"]
+          :encoding => site.config["encoding"],
         }).map(&:to_hash)
       else
         SafeYAML.load_file(path)
diff --git a/lib/jekyll/readers/post_reader.rb b/lib/jekyll/readers/post_reader.rb
index 123709e7..70688875 100644
--- a/lib/jekyll/readers/post_reader.rb
+++ b/lib/jekyll/readers/post_reader.rb
@@ -57,7 +57,7 @@ module Jekyll
         path = @site.in_source_dir(File.join(dir, magic_dir, entry))
         Document.new(path, {
           :site       => @site,
-          :collection => @site.posts
+          :collection => @site.posts,
         })
       end.reject(&:nil?)
     end
diff --git a/lib/jekyll/regenerator.rb b/lib/jekyll/regenerator.rb
index 4d89da2e..09ff309a 100644
--- a/lib/jekyll/regenerator.rb
+++ b/lib/jekyll/regenerator.rb
@@ -40,7 +40,7 @@ module Jekyll
 
       metadata[path] = {
         "mtime" => File.mtime(path),
-        "deps"  => []
+        "deps"  => [],
       }
       cache[path] = true
     end
diff --git a/lib/jekyll/site.rb b/lib/jekyll/site.rb
index 5797df77..87ea719b 100644
--- a/lib/jekyll/site.rb
+++ b/lib/jekyll/site.rb
@@ -435,7 +435,7 @@ module Jekyll
     private
     def configure_include_paths
       @includes_load_paths = Array(in_source_dir(config["includes_dir"].to_s))
-      @includes_load_paths << theme.includes_path if self.theme
+      @includes_load_paths << theme.includes_path if theme && theme.includes_path
     end
 
     private
diff --git a/lib/jekyll/static_file.rb b/lib/jekyll/static_file.rb
index 927a9b47..53b945d4 100644
--- a/lib/jekyll/static_file.rb
+++ b/lib/jekyll/static_file.rb
@@ -101,7 +101,7 @@ module Jekyll
         "name"          => name,
         "extname"       => extname,
         "modified_time" => modified_time,
-        "path"          => File.join("", relative_path)
+        "path"          => File.join("", relative_path),
       }
     end
 
@@ -112,7 +112,7 @@ module Jekyll
           @collection.relative_directory.size..relative_path.size],
         :output_ext => "",
         :name       => "",
-        :title      => ""
+        :title      => "",
       }
     end
 
@@ -125,7 +125,7 @@ module Jekyll
                else
                  ::Jekyll::URL.new({
                    :template     => @collection.url_template,
-                   :placeholders => placeholders
+                   :placeholders => placeholders,
                  })
                end.to_s.gsub(%r!/$!, "")
     end
diff --git a/lib/jekyll/tags/highlight.rb b/lib/jekyll/tags/highlight.rb
index 43b0c62f..86b9171b 100644
--- a/lib/jekyll/tags/highlight.rb
+++ b/lib/jekyll/tags/highlight.rb
@@ -54,7 +54,7 @@ eos
             [:hl_lines,    opts.fetch(:hl_lines, nil)],
             [:linenos,     opts.fetch(:linenos, nil)],
             [:encoding,    opts.fetch(:encoding, "utf-8")],
-            [:cssclass,    opts.fetch(:cssclass, nil)]
+            [:cssclass,    opts.fetch(:cssclass, nil)],
           ].reject { |f| f.last.nil? }]
         else
           opts
@@ -125,7 +125,7 @@ eos
       def add_code_tag(code)
         code_attributes = [
           "class=\"language-#{@lang.to_s.tr("+", "-")}\"",
-          "data-lang=\"#{@lang}\""
+          "data-lang=\"#{@lang}\"",
         ].join(" ")
         "<figure class=\"highlight\"><pre><code #{code_attributes}>"\
         "#{code.chomp}</code></pre></figure>"
diff --git a/lib/jekyll/tags/include.rb b/lib/jekyll/tags/include.rb
index 67461750..08843047 100644
--- a/lib/jekyll/tags/include.rb
+++ b/lib/jekyll/tags/include.rb
@@ -112,8 +112,8 @@ eos
       def locate_include_file(context, file, safe)
         includes_dirs = tag_includes_dirs(context)
         includes_dirs.each do |dir|
-          path = File.join(dir, file)
-          return path if valid_include_file?(path, dir, safe)
+          path = File.join(dir.to_s, file.to_s)
+          return path if valid_include_file?(path, dir.to_s, safe)
         end
         raise IOError, "Could not locate the included file '#{file}' in any of "\
           "#{includes_dirs}. Ensure it exists in one of those directories and, "\
@@ -155,15 +155,19 @@ eos
         if cached_partial.key?(path)
           cached_partial[path]
         else
-          cached_partial[path] = context.registers[:site]
+          unparsed_file = context.registers[:site]
             .liquid_renderer
             .file(path)
-            .parse(read_file(path, context))
+          begin
+            cached_partial[path] = unparsed_file.parse(read_file(path, context))
+          rescue Liquid::SyntaxError => ex
+            raise IncludeTagError.new(ex.message, path)
+          end
         end
       end
 
       def valid_include_file?(path, dir, safe)
-        !(outside_site_source?(path, dir, safe) || !File.exist?(path))
+        !outside_site_source?(path, dir, safe) && File.file?(path)
       end
 
       def outside_site_source?(path, dir, safe)
diff --git a/lib/jekyll/theme_builder.rb b/lib/jekyll/theme_builder.rb
index 68a5eeab..f1c97e37 100644
--- a/lib/jekyll/theme_builder.rb
+++ b/lib/jekyll/theme_builder.rb
@@ -28,7 +28,7 @@ class Jekyll::ThemeBuilder
   def template_file(filename)
     [
       root.join("theme_template", "#{filename}.erb"),
-      root.join("theme_template", filename.to_s)
+      root.join("theme_template", filename.to_s),
     ].find(&:exist?)
   end
 
diff --git a/lib/jekyll/utils.rb b/lib/jekyll/utils.rb
index 23bacdab..3f91a2b0 100644
--- a/lib/jekyll/utils.rb
+++ b/lib/jekyll/utils.rb
@@ -2,8 +2,9 @@
 module Jekyll
   module Utils
     extend self
-    autoload :Platforms, "jekyll/utils/platforms"
     autoload :Ansi, "jekyll/utils/ansi"
+    autoload :Exec, "jekyll/utils/exec"
+    autoload :Platforms, "jekyll/utils/platforms"
     autoload :WinTZ, "jekyll/utils/win_tz"
 
     # Constants for use in #slugify
diff --git a/lib/jekyll/utils/ansi.rb b/lib/jekyll/utils/ansi.rb
index 4be163c5..8bdd2322 100644
--- a/lib/jekyll/utils/ansi.rb
+++ b/lib/jekyll/utils/ansi.rb
@@ -17,7 +17,7 @@ module Jekyll
         :yellow  => 33,
         :white   => 37,
         :blue    => 34,
-        :cyan    => 36
+        :cyan    => 36,
       }.freeze
 
       # Strip ANSI from the current string.  It also strips cursor stuff,
diff --git a/lib/jekyll/utils/exec.rb b/lib/jekyll/utils/exec.rb
new file mode 100644
index 00000000..33403dbc
--- /dev/null
+++ b/lib/jekyll/utils/exec.rb
@@ -0,0 +1,25 @@
+require "open3"
+
+module Jekyll
+  module Utils
+    module Exec
+      extend self
+
+      # Runs a program in a sub-shell.
+      #
+      # *args - a list of strings containing the program name and arguments
+      #
+      # Returns a Process::Status and a String of output in an array in
+      # that order.
+      def run(*args)
+        stdin, stdout, stderr, process = Open3.popen3(*args)
+        out = stdout.read.strip
+        err = stderr.read.strip
+
+        [stdin, stdout, stderr].each(&:close)
+        [process.value, out + err]
+      end
+
+    end
+  end
+end
diff --git a/rake/docs.rake b/rake/docs.rake
index aec162b5..fcae4f20 100644
--- a/rake/docs.rake
+++ b/rake/docs.rake
@@ -7,7 +7,7 @@
 namespace :docs do
   desc "Release #{docs_name} v#{version}"
   task :release => :build do
-    unless `git branch` =~ /^\* master$/
+    unless `git branch` =~ %r!^\* master$!
       puts "You must be on the master branch to release!"
       exit!
     end
diff --git a/rake/release.rake b/rake/release.rake
index a78690d8..832b5bb3 100644
--- a/rake/release.rake
+++ b/rake/release.rake
@@ -6,7 +6,7 @@
 
 desc "Release #{name} v#{version}"
 task :release => :build do
-  unless `git branch` =~ /^\* master$/
+  unless `git branch` =~ %r!^\* master$!
     puts "You must be on the master branch to release!"
     exit!
   end
diff --git a/rake/site.rake b/rake/site.rake
index 2fb4172a..63b04fc8 100644
--- a/rake/site.rake
+++ b/rake/site.rake
@@ -13,7 +13,7 @@ namespace :site do
     require "jekyll"
 
     browser_launched = false
-    Jekyll::Hooks.register :site, :post_write do |site|
+    Jekyll::Hooks.register :site, :post_write do |_site|
       next if browser_launched
       browser_launched = true
       Jekyll.logger.info "Opening in browser..."
@@ -26,7 +26,7 @@ namespace :site do
       "source"      => File.expand_path(docs_folder),
       "destination" => File.expand_path("#{docs_folder}/_site"),
       "watch"       => true,
-      "serving"     => true
+      "serving"     => true,
     }
     Jekyll::Commands::Build.process(options)
     Jekyll::Commands::Serve.process(options)
@@ -38,7 +38,7 @@ namespace :site do
     Jekyll::Commands::Build.process({
       "profile"     => true,
       "source"      => File.expand_path(docs_folder),
-      "destination" => File.expand_path("#{docs_folder}/_site")
+      "destination" => File.expand_path("#{docs_folder}/_site"),
     })
   end
   task :build => :generate
@@ -48,7 +48,7 @@ namespace :site do
     Dir.chdir("#{docs_folder}/_sass") do
       sh 'curl "https://necolas.github.io/normalize.css/latest/normalize.css" -o "normalize.scss"'
       sh 'sass "normalize.scss":"_normalize.scss" --style compressed'
-      rm ['normalize.scss', Dir.glob('*.map')].flatten
+      rm ["normalize.scss", Dir.glob("*.map")].flatten
     end
   end
 
@@ -60,40 +60,40 @@ namespace :site do
 
   desc "Create a nicely formatted history page for the jekyll site based on the repo history."
   task :history do
-    siteify_file('History.markdown', { "title" => "History" })
+    siteify_file("History.markdown", { "title" => "History" })
   end
 
   desc "Copy the Code of Conduct"
   task :conduct do
     front_matter = {
       "redirect_from" => "/conduct/index.html",
-      "editable"      => false
+      "editable"      => false,
     }
-    siteify_file('CONDUCT.markdown', front_matter)
+    siteify_file("CONDUCT.markdown", front_matter)
   end
 
   desc "Copy the contributing file"
   task :contributing do
-    siteify_file('.github/CONTRIBUTING.markdown', "title" => "Contributing")
+    siteify_file(".github/CONTRIBUTING.markdown", "title" => "Contributing")
   end
 
   desc "Write the site latest_version.txt file"
   task :version_file do
-    File.open("#{docs_folder}/latest_version.txt", 'wb') { |f| f.puts(version) } unless version =~ /(beta|rc|alpha)/i
+    File.open("#{docs_folder}/latest_version.txt", "wb") { |f| f.puts(version) } unless version =~ %r!(beta|rc|alpha)!i
   end
 
   namespace :releases do
     desc "Create new release post"
-    task :new, :version do |t, args|
+    task :new, :version do |_t, args|
       raise "Specify a version: rake site:releases:new['1.2.3']" unless args.version
-      today = Time.new.strftime('%Y-%m-%d')
+      today = Time.new.strftime("%Y-%m-%d")
       release = args.version.to_s
-      filename = "#{docs_folder}/_posts/#{today}-jekyll-#{release.split('.').join('-')}-released.markdown"
+      filename = "#{docs_folder}/_posts/#{today}-jekyll-#{release.split(".").join("-")}-released.markdown"
 
       File.open(filename, "wb") do |post|
         post.puts("---")
         post.puts("title: 'Jekyll #{release} Released'")
-        post.puts("date: #{Time.new.strftime('%Y-%m-%d %H:%M:%S %z')}")
+        post.puts("date: #{Time.new.strftime("%Y-%m-%d %H:%M:%S %z")}")
         post.puts("author: ")
         post.puts("version: #{release}")
         post.puts("categories: [release]")
diff --git a/script/proof b/script/proof
index 1dd63a28..664e778d 100755
--- a/script/proof
+++ b/script/proof
@@ -32,4 +32,4 @@ bundle exec jekyll build -s $SOURCE -d $DESTINATION --trace
 
 # 3.
 msg "Proofing..."
-time bundle exec htmlproof ./$DESTINATION --url-ignore $INGORE_HREFS $@
+time bundle exec htmlproofer ./$DESTINATION --url-ignore $INGORE_HREFS $@
diff --git a/test/helper.rb b/test/helper.rb
index 0c6935a0..94bad2cc 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -46,7 +46,7 @@ include Jekyll
 Minitest::Reporters.use! [
   Minitest::Reporters::DefaultReporter.new(
     :color => true
-  )
+  ),
 ]
 
 module Minitest::Assertions
@@ -62,6 +62,10 @@ module Minitest::Assertions
 end
 
 module DirectoryHelpers
+  def root_dir(*subdirs)
+    File.join(File.dirname(File.dirname(__FILE__)), *subdirs)
+  end
+
   def dest_dir(*subdirs)
     test_dir("dest", *subdirs)
   end
@@ -70,8 +74,12 @@ module DirectoryHelpers
     test_dir("source", *subdirs)
   end
 
+  def theme_dir(*subdirs)
+    test_dir("fixtures", "test-theme", *subdirs)
+  end
+
   def test_dir(*subdirs)
-    File.join(File.dirname(__FILE__), *subdirs)
+    root_dir("test", *subdirs)
   end
 end
 
@@ -107,9 +115,9 @@ class JekyllUnitTest < Minitest::Test
     site = fixture_site({
       "collections" => {
         "methods" => {
-          "output" => true
-        }
-      }
+          "output" => true,
+        },
+      },
     })
     site.read
     matching_doc = site.collections["methods"].docs.find do |doc|
@@ -133,10 +141,10 @@ class JekyllUnitTest < Minitest::Test
   def site_configuration(overrides = {})
     full_overrides = build_configs(overrides, build_configs({
       "destination" => dest_dir,
-      "incremental" => false
+      "incremental" => false,
     }))
     Configuration.from(full_overrides.merge({
-      "source" => source_dir
+      "source" => source_dir,
     }))
   end
 
@@ -159,11 +167,11 @@ class JekyllUnitTest < Minitest::Test
   end
 
   def capture_output
-    stderr = StringIO.new
-    Jekyll.logger = Logger.new stderr
+    buffer = StringIO.new
+    Jekyll.logger = Logger.new(buffer)
     yield
-    stderr.rewind
-    return stderr.string.to_s
+    buffer.rewind
+    buffer.string.to_s
   end
   alias_method :capture_stdout, :capture_output
   alias_method :capture_stderr, :capture_output
diff --git a/test/source/_plugins/dummy.rb b/test/source/_plugins/dummy.rb
index bfd46e1c..fd11d0e1 100644
--- a/test/source/_plugins/dummy.rb
+++ b/test/source/_plugins/dummy.rb
@@ -2,7 +2,6 @@ module Jekyll
   class Dummy < Generator
     priority :high
 
-    def generate(site)
-    end
+    def generate(site) end
   end
 end
diff --git a/test/test_collections.rb b/test/test_collections.rb
index 0dca8443..0607208b 100644
--- a/test/test_collections.rb
+++ b/test/test_collections.rb
@@ -91,9 +91,9 @@ class TestCollections < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "methods" => {
-            "permalink" => "/awesome/:path/"
-          }
-        }
+            "permalink" => "/awesome/:path/",
+          },
+        },
       })
       @site.process
       @collection = @site.collections["methods"]
@@ -107,7 +107,7 @@ class TestCollections < JekyllUnitTest
   context "with a collection" do
     setup do
       @site = fixture_site({
-        "collections" => ["methods"]
+        "collections" => ["methods"],
       })
       @site.process
       @collection = @site.collections["methods"]
@@ -158,9 +158,9 @@ class TestCollections < JekyllUnitTest
         "collections" => {
           "methods" => {
             "foo" => "bar",
-            "baz" => "whoo"
-          }
-        }
+            "baz" => "whoo",
+          },
+        },
       })
       @site.process
       @collection = @site.collections["methods"]
@@ -175,7 +175,7 @@ class TestCollections < JekyllUnitTest
     setup do
       @site = fixture_site({
         "collections" => ["methods"],
-        "safe"        => true
+        "safe"        => true,
       })
       @site.process
       @collection = @site.collections["methods"]
@@ -198,7 +198,7 @@ class TestCollections < JekyllUnitTest
     setup do
       @site = fixture_site({
         "collections" => ["with.dots"],
-        "safe"        => true
+        "safe"        => true,
       })
       @site.process
       @collection = @site.collections["with.dots"]
diff --git a/test/test_commands_serve.rb b/test/test_commands_serve.rb
index 143dc2a5..fa0f7f67 100644
--- a/test/test_commands_serve.rb
+++ b/test/test_commands_serve.rb
@@ -86,12 +86,12 @@ class TestCommandsServe < JekyllUnitTest
           "config"  => %w(_config.yml _development.yml),
           "serving" => true,
           "watch"   => false, # for not having guard output when running the tests
-          "url"     => "http://localhost:4000"
+          "url"     => "http://localhost:4000",
         }
 
         expect(Jekyll::Commands::Serve).to receive(:process).with(custom_options)
         @merc.execute(:serve, { "config" => %w(_config.yml _development.yml),
-                                "watch"  => false })
+                                "watch"  => false, })
       end
 
       context "in development environment" do
@@ -113,7 +113,7 @@ class TestCommandsServe < JekyllUnitTest
             "port"     => "9999",
             "url"      => "https://jekyllrb.com/",
             "ssl_cert" => "foo",
-            "ssl_key"  => "bar"
+            "ssl_key"  => "bar",
           })
 
           assert_equal 1, Jekyll.sites.count
@@ -146,13 +146,13 @@ class TestCommandsServe < JekyllUnitTest
         should "raise if enabling without key or cert" do
           assert_raises RuntimeError do
             custom_opts({
-              "ssl_key" => "foo"
+              "ssl_key" => "foo",
             })
           end
 
           assert_raises RuntimeError do
             custom_opts({
-              "ssl_key" => "foo"
+              "ssl_key" => "foo",
             })
           end
         end
@@ -166,7 +166,7 @@ class TestCommandsServe < JekyllUnitTest
             "ssl_cert"   => "foo",
             "source"     => "bar",
             "enable_ssl" => true,
-            "ssl_key"    => "bar"
+            "ssl_key"    => "bar",
           })
 
           assert result[:SSLEnable]
diff --git a/test/test_configuration.rb b/test/test_configuration.rb
index 696fc3e9..febc0cbe 100644
--- a/test/test_configuration.rb
+++ b/test/test_configuration.rb
@@ -4,7 +4,7 @@ require "colorator"
 class TestConfiguration < JekyllUnitTest
   test_config = {
     "source"      => new(nil).source_dir,
-    "destination" => dest_dir
+    "destination" => dest_dir,
   }
 
   context ".from" do
@@ -34,8 +34,8 @@ class TestConfiguration < JekyllUnitTest
         {
           "posts" => {
             "output"    => true,
-            "permalink" => "/:categories/:year/:month/:day/:title:output_ext"
-          }
+            "permalink" => "/:categories/:year/:month/:day/:title:output_ext",
+          },
         }
       )
     end
@@ -85,8 +85,8 @@ class TestConfiguration < JekyllUnitTest
         {
           "posts" => {
             "output"    => true,
-            "permalink" => "/:categories/:year/:month/:day/:title/"
-          }
+            "permalink" => "/:categories/:year/:month/:day/:title/",
+          },
         }
       )
 
@@ -109,14 +109,14 @@ class TestConfiguration < JekyllUnitTest
         :permalink => "date",
         "baseurl"  => "/",
         :include   => [".htaccess"],
-        :source    => "./"
+        :source    => "./",
       }]
       @string_keys = Configuration[{
         "markdown"  => "kramdown",
         "permalink" => "date",
         "baseurl"   => "/",
         "include"   => [".htaccess"],
-        "source"    => "./"
+        "source"    => "./",
       }]
     end
     should "stringify symbol keys" do
@@ -132,7 +132,7 @@ class TestConfiguration < JekyllUnitTest
       @no_override     = {}
       @one_config_file = { "config" => "config.yml" }
       @multiple_files  = {
-        "config" => %w(config/site.yml config/deploy.toml configuration.yml)
+        "config" => %w(config/site.yml config/deploy.toml configuration.yml),
       }
     end
 
@@ -205,7 +205,7 @@ class TestConfiguration < JekyllUnitTest
         "pygments"    => true,
         "plugins"     => true,
         "layouts"     => true,
-        "data_source" => true
+        "data_source" => true,
       }]
     end
     should "unset 'auto' and 'watch'" do
@@ -255,7 +255,7 @@ class TestConfiguration < JekyllUnitTest
     setup do
       @config = proc do |val|
         Configuration[{
-          "paginate" => val
+          "paginate" => val,
         }]
       end
     end
@@ -327,7 +327,7 @@ class TestConfiguration < JekyllUnitTest
         :default => source_dir("_config.yml"),
         :other   => source_dir("_config.live.yml"),
         :toml    => source_dir("_config.dev.toml"),
-        :empty   => ""
+        :empty   => "",
       }
     end
 
@@ -372,7 +372,7 @@ class TestConfiguration < JekyllUnitTest
       Jekyll.logger.log_level = :warn
       assert_equal \
         site_configuration({ "baseurl" => "/you-beautiful-blog-you",
-                             "title"   => "My magnificent site, wut" }),
+                             "title"   => "My magnificent site, wut", }),
         Jekyll.configuration(test_config.merge({ "config" => [@paths[:toml]] }))
       Jekyll.logger.log_level = :info
     end
@@ -435,9 +435,9 @@ class TestConfiguration < JekyllUnitTest
           "docs"  => {},
           "posts" => {
             "output"    => true,
-            "permalink" => "/:categories/:year/:month/:day/:title:output_ext"
-          }
-        }
+            "permalink" => "/:categories/:year/:month/:day/:title:output_ext",
+          },
+        },
       })
     end
 
@@ -449,9 +449,9 @@ class TestConfiguration < JekyllUnitTest
         "collections" => {
           "posts" => {
             "output"    => true,
-            "permalink" => "/:categories/:year/:month/:day/:title:output_ext"
-          }
-        }
+            "permalink" => "/:categories/:year/:month/:day/:title:output_ext",
+          },
+        },
       })
     end
 
@@ -461,9 +461,9 @@ class TestConfiguration < JekyllUnitTest
         "collections" => {
           "posts" => {
             "output"    => true,
-            "permalink" => "/:categories/:year/:month/:day/:title:output_ext"
-          }
-        }
+            "permalink" => "/:categories/:year/:month/:day/:title:output_ext",
+          },
+        },
       })
     end
 
@@ -471,16 +471,16 @@ class TestConfiguration < JekyllUnitTest
       posts_permalink = "/:year/:title/"
       conf = Configuration[default_configuration].tap do |c|
         c["collections"] = {
-          "posts" => { "permalink" => posts_permalink }
+          "posts" => { "permalink" => posts_permalink },
         }
       end
       assert_equal conf.add_default_collections, conf.merge({
         "collections" => {
           "posts" => {
             "output"    => true,
-            "permalink" => posts_permalink
-          }
-        }
+            "permalink" => posts_permalink,
+          },
+        },
       })
     end
   end
diff --git a/test/test_doctor_command.rb b/test/test_doctor_command.rb
index 652175b9..88614402 100644
--- a/test/test_doctor_command.rb
+++ b/test/test_doctor_command.rb
@@ -10,7 +10,7 @@ class TestDoctorCommand < JekyllUnitTest
     should "return success on a valid site/page" do
       @site = Site.new(Jekyll.configuration({
         "source"      => File.join(source_dir, "/_urls_differ_by_case_valid"),
-        "destination" => dest_dir
+        "destination" => dest_dir,
       }))
       @site.process
       output = capture_stderr do
@@ -23,7 +23,7 @@ class TestDoctorCommand < JekyllUnitTest
     should "return warning for pages only differing by case" do
       @site = Site.new(Jekyll.configuration({
         "source"      => File.join(source_dir, "/_urls_differ_by_case_invalid"),
-        "destination" => dest_dir
+        "destination" => dest_dir,
       }))
       @site.process
       output = capture_stderr do
diff --git a/test/test_document.rb b/test/test_document.rb
index 7c9df18c..f274dd53 100644
--- a/test/test_document.rb
+++ b/test/test_document.rb
@@ -8,7 +8,7 @@ class TestDocument < JekyllUnitTest
   context "a document in a collection" do
     setup do
       @site = fixture_site({
-        "collections" => ["methods"]
+        "collections" => ["methods"],
       })
       @site.process
       @document = @site.collections["methods"].docs.detect do |d|
@@ -118,10 +118,10 @@ class TestDocument < JekyllUnitTest
           "scope"  => { "path"=>"", "type"=>"slides" },
           "values" => {
             "nested" => {
-              "key" => "myval"
-            }
-          }
-        }]
+              "key" => "myval",
+            },
+          },
+        },],
       })
       @site.process
       @document = @site.collections["slides"].docs.select { |d| d.is_a?(Document) }.first
@@ -143,10 +143,10 @@ class TestDocument < JekyllUnitTest
           "values" => {
             "nested" => {
               "test1" => "default1",
-              "test2" => "default1"
-            }
-          }
-        }]
+              "test2" => "default1",
+            },
+          },
+        },],
       })
       @site.process
       @document = @site.collections["slides"].docs[1]
@@ -170,10 +170,10 @@ class TestDocument < JekyllUnitTest
           "scope"  => { "path"=>"_slides", "type"=>"slides" },
           "values" => {
             "nested" => {
-              "key" => "value123"
-            }
-          }
-        }]
+              "key" => "value123",
+            },
+          },
+        },],
       })
       @site.process
       @document = @site.collections["slides"].docs.first
@@ -194,10 +194,10 @@ class TestDocument < JekyllUnitTest
           "scope"  => { "path"=>"somepath", "type"=>"slides" },
           "values" => {
             "nested" => {
-              "key" => "myval"
-            }
-          }
-        }]
+              "key" => "myval",
+            },
+          },
+        },],
       })
       @site.process
       @document = @site.collections["slides"].docs.first
@@ -213,7 +213,7 @@ class TestDocument < JekyllUnitTest
   context "a document in a collection with a custom permalink" do
     setup do
       @site = fixture_site({
-        "collections" => ["slides"]
+        "collections" => ["slides"],
       })
       @site.process
       @document = @site.collections["slides"].docs[2]
@@ -235,10 +235,10 @@ class TestDocument < JekyllUnitTest
         "collections" => {
           "slides" => {
             "output"    => true,
-            "permalink" => "/slides/test/:name"
-          }
+            "permalink" => "/slides/test/:name",
+          },
         },
-        "permalink"   => "pretty"
+        "permalink"   => "pretty",
       })
       @site.process
       @document = @site.collections["slides"].docs[0]
@@ -263,9 +263,9 @@ class TestDocument < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "slides" => {
-            "output" => true
-          }
-        }
+            "output" => true,
+          },
+        },
       })
       @site.permalink_style = :pretty
       @site.process
@@ -287,9 +287,9 @@ class TestDocument < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "slides" => {
-            "output" => true
-          }
-        }
+            "output" => true,
+          },
+        },
       })
       @site.permalink_style = :pretty
       @site.process
@@ -307,9 +307,9 @@ class TestDocument < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "slides" => {
-            "output" => true
-          }
-        }
+            "output" => true,
+          },
+        },
       })
       @site.process
       @document = @site.collections["slides"].docs[6]
@@ -339,9 +339,9 @@ class TestDocument < JekyllUnitTest
         "collections" => {
           "slides" => {
             "output"    => true,
-            "permalink" => "/slides/:title"
-          }
-        }
+            "permalink" => "/slides/:title",
+          },
+        },
       })
       @site.process
       @document = @site.collections["slides"].docs[3]
@@ -381,8 +381,8 @@ class TestDocument < JekyllUnitTest
   context "document with a permalink with dots & a trailing slash" do
     setup do
       @site = fixture_site({ "collections" => {
-        "with.dots" => { "output" => true }
-      } })
+        "with.dots" => { "output" => true },
+      }, })
       @site.process
       @document = @site.collections["with.dots"].docs.last
       @dest_file = dest_dir("with.dots", "permalink.with.slash.tho", "index.html")
@@ -406,9 +406,9 @@ class TestDocument < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "slides" => {
-            "output" => true
-          }
-        }
+            "output" => true,
+          },
+        },
       })
       @site.process
       @files = @site.collections["slides"].docs
@@ -436,9 +436,9 @@ class TestDocument < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "slides" => {
-            "output" => true
-          }
-        }
+            "output" => true,
+          },
+        },
       })
       @site.process
       @document = @site.collections["slides"].files.find do |doc|
@@ -469,9 +469,9 @@ class TestDocument < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "methods" => {
-            "output" => true
-          }
-        }
+            "output" => true,
+          },
+        },
       })
       @site.process
       @document = @site.collections["methods"].docs.find do |doc|
@@ -498,9 +498,9 @@ class TestDocument < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "methods" => {
-            "output" => true
-          }
-        }
+            "output" => true,
+          },
+        },
       })
       @site.process
       @document = @site.collections["methods"].docs.find do |doc|
diff --git a/test/test_drop.rb b/test/test_drop.rb
index 199e94ab..80b0d0ff 100644
--- a/test/test_drop.rb
+++ b/test/test_drop.rb
@@ -4,7 +4,7 @@ class TestDrop < JekyllUnitTest
   context "a document drop" do
     setup do
       @site = fixture_site({
-        "collections" => ["methods"]
+        "collections" => ["methods"],
       })
       @site.process
       @document = @site.collections["methods"].docs.detect do |d|
diff --git a/test/test_entry_filter.rb b/test/test_entry_filter.rb
index f65badc6..7f32653c 100644
--- a/test/test_entry_filter.rb
+++ b/test/test_entry_filter.rb
@@ -17,7 +17,7 @@ class TestEntryFilter < JekyllUnitTest
     should "allow regexp filtering" do
       files = %w(README.md)
       @site.exclude = [
-        %r!README!
+        %r!README!,
       ]
 
       assert_empty @site.reader.filter_entries(
diff --git a/test/test_excerpt.rb b/test/test_excerpt.rb
index 0b7e540f..e0960f69 100644
--- a/test/test_excerpt.rb
+++ b/test/test_excerpt.rb
@@ -4,13 +4,13 @@ class TestExcerpt < JekyllUnitTest
   def setup_post(file)
     Document.new(@site.in_source_dir(File.join("_posts", file)), {
       :site       => @site,
-      :collection => @site.posts
+      :collection => @site.posts,
     }).tap(&:read)
   end
 
   def do_render(document)
     @site.layouts = {
-      "default" => Layout.new(@site, source_dir("_layouts"), "simple.html")
+      "default" => Layout.new(@site, source_dir("_layouts"), "simple.html"),
     }
     document.output = Jekyll::Renderer.new(@site, document, @site.site_payload).run
   end
diff --git a/test/test_filters.rb b/test/test_filters.rb
index e5dedfae..d18b57e3 100644
--- a/test/test_filters.rb
+++ b/test/test_filters.rb
@@ -29,7 +29,7 @@ class TestFilters < JekyllUnitTest
       @filter = make_filter_mock({
         "timezone" => "UTC",
         "url"      => "http://example.com",
-        "baseurl"  => "/base"
+        "baseurl"  => "/base",
       })
       @sample_time = Time.utc(2013, 3, 27, 11, 22, 33)
       @sample_date = Date.parse("2013-03-27")
@@ -39,7 +39,7 @@ class TestFilters < JekyllUnitTest
       @array_of_objects = [
         { "color" => "red",  "size" => "large"  },
         { "color" => "red",  "size" => "medium" },
-        { "color" => "blue", "size" => "medium" }
+        { "color" => "blue", "size" => "medium" },
       ]
     end
 
@@ -332,7 +332,7 @@ class TestFilters < JekyllUnitTest
         page_url = "about/my_favorite_page/"
         filter = make_filter_mock({
           "url"     => "http://example.com",
-          "baseurl" => "base"
+          "baseurl" => "base",
         })
         assert_equal "http://example.com/base/#{page_url}", filter.absolute_url(page_url)
       end
@@ -341,7 +341,7 @@ class TestFilters < JekyllUnitTest
         page_url = "about/my_favorite_page/"
         filter = make_filter_mock({
           "url"     => "",
-          "baseurl" => "base"
+          "baseurl" => "base",
         })
         assert_equal "/base/#{page_url}", filter.absolute_url(page_url)
       end
@@ -350,7 +350,7 @@ class TestFilters < JekyllUnitTest
         page_url = "about/my_favorite_page/"
         filter = make_filter_mock({
           "url"     => nil,
-          "baseurl" => "base"
+          "baseurl" => "base",
         })
         assert_equal "/base/#{page_url}", filter.absolute_url(page_url)
       end
@@ -359,7 +359,7 @@ class TestFilters < JekyllUnitTest
         page_url = "about/my_favorite_page/"
         filter = make_filter_mock({
           "url"     => "http://example.com",
-          "baseurl" => nil
+          "baseurl" => nil,
         })
         assert_equal "http://example.com/#{page_url}", filter.absolute_url(page_url)
       end
@@ -368,16 +368,34 @@ class TestFilters < JekyllUnitTest
         page_url = ""
         filter = make_filter_mock({
           "url"     => "http://example.com",
-          "baseurl" => "/base"
+          "baseurl" => "/base",
         })
         assert_equal "http://example.com/base", filter.absolute_url(page_url)
       end
 
+      should "not append a forward slash if input is '/'" do
+        page_url = "/"
+        filter = make_filter_mock({
+          "url"     => "http://example.com",
+          "baseurl" => "/base",
+        })
+        assert_equal "http://example.com/base/", filter.absolute_url(page_url)
+      end
+
+      should "not append a forward slash if input is '/' and nil 'baseurl'" do
+        page_url = "/"
+        filter = make_filter_mock({
+          "url"     => "http://example.com",
+          "baseurl" => nil,
+        })
+        assert_equal "http://example.com/", filter.absolute_url(page_url)
+      end
+
       should "normalize international URLs" do
         page_url = ""
         filter = make_filter_mock({
           "url"     => "http://ümlaut.example.org/",
-          "baseurl" => nil
+          "baseurl" => nil,
         })
         assert_equal "http://xn--mlaut-jva.example.org/", filter.absolute_url(page_url)
       end
@@ -409,7 +427,7 @@ class TestFilters < JekyllUnitTest
         page_url = "about/my_favorite_page/"
         filter = make_filter_mock({
           "url"     => "http://example.com",
-          "baseurl" => nil
+          "baseurl" => nil,
         })
         assert_equal "/#{page_url}", filter.relative_url(page_url)
       end
@@ -418,7 +436,7 @@ class TestFilters < JekyllUnitTest
         page_url = ""
         filter = make_filter_mock({
           "url"     => "http://example.com",
-          "baseurl" => "/base"
+          "baseurl" => "/base",
         })
         assert_equal "/base", filter.relative_url(page_url)
       end
@@ -451,7 +469,7 @@ class TestFilters < JekyllUnitTest
           "excerpt"       => "<p>This should be published.</p>\n",
           "draft"         => false,
           "categories"    => [
-            "publish_test"
+            "publish_test",
           ],
           "layout"        => "default",
           "title"         => "Publish",
@@ -459,7 +477,7 @@ class TestFilters < JekyllUnitTest
           "date"          => "2008-02-02 00:00:00 +0000",
           "slug"          => "published",
           "ext"           => ".markdown",
-          "tags"          => []
+          "tags"          => [],
         }
         actual = JSON.parse(@filter.jsonify(@filter.site.docs_to_write.first.to_liquid))
 
@@ -475,7 +493,7 @@ class TestFilters < JekyllUnitTest
         actual = @filter.jsonify(@filter.site.to_liquid)
         assert_equal JSON.parse(actual)["jekyll"], {
           "environment" => "development",
-          "version"     => Jekyll::VERSION
+          "version"     => Jekyll::VERSION,
         }
       end
 
@@ -491,7 +509,7 @@ class TestFilters < JekyllUnitTest
             "name" => name,
             :v     => 1,
             :thing => M.new({ :kay => "jewelers" }),
-            :stuff => true
+            :stuff => true,
           }
         end
       end
@@ -503,21 +521,21 @@ class TestFilters < JekyllUnitTest
             "v"     => 1,
             "thing" => [
               {
-                "kay" => "jewelers"
-              }
+                "kay" => "jewelers",
+              },
             ],
-            "stuff" => true
+            "stuff" => true,
           },
           {
             "name"  => "Smathers",
             "v"     => 1,
             "thing" => [
               {
-                "kay" => "jewelers"
-              }
+                "kay" => "jewelers",
+              },
             ],
-            "stuff" => true
-          }
+            "stuff" => true,
+          },
         ]
         result = @filter.jsonify([T.new("Jeremiah"), T.new("Smathers")])
         assert_equal expected, JSON.parse(result)
@@ -533,32 +551,32 @@ class TestFilters < JekyllUnitTest
               "v"     => 1,
               "thing" => [
                 {
-                  "kay" => "jewelers"
-                }
+                  "kay" => "jewelers",
+                },
               ],
-              "stuff" => true
+              "stuff" => true,
             },
             {
               "name"  => 1,
               "v"     => 1,
               "thing" => [
                 {
-                  "kay" => "jewelers"
-                }
+                  "kay" => "jewelers",
+                },
               ],
-              "stuff" => true
+              "stuff" => true,
             },
             {
               "name"  => 2,
               "v"     => 1,
               "thing" => [
                 {
-                  "kay" => "jewelers"
-                }
+                  "kay" => "jewelers",
+                },
               ],
-              "stuff" => true
-            }
-          ]
+              "stuff" => true,
+            },
+          ],
         }
         result = @filter.jsonify(my_hash)
         assert_equal expected, JSON.parse(result)
@@ -633,7 +651,7 @@ class TestFilters < JekyllUnitTest
         hash = {
           "a" => { "tags"=>%w(x y) },
           "b" => { "tags"=>["x"] },
-          "c" => { "tags"=>%w(y z) }
+          "c" => { "tags"=>%w(y z) },
         }
         assert_equal 2, @filter.where(hash, "tags", "x").length
       end
@@ -642,7 +660,7 @@ class TestFilters < JekyllUnitTest
         hash = {
           "a" => { "tags"=>%w(x y) },
           "b" => { "tags"=>"x" },
-          "c" => { "tags"=>%w(y z) }
+          "c" => { "tags"=>%w(y z) },
         }
         assert_equal 2, @filter.where(hash, "tags", "x").length
       end
@@ -651,7 +669,7 @@ class TestFilters < JekyllUnitTest
         hash = {
           "a" => { "category"=>"bear" },
           "b" => { "category"=>"wolf" },
-          "c" => { "category"=>%w(bear lion) }
+          "c" => { "category"=>%w(bear lion) },
         }
         assert_equal 0, @filter.where(hash, "category", "ear").length
       end
@@ -660,7 +678,7 @@ class TestFilters < JekyllUnitTest
         hash = {
           "The Words" => { "rating" => 1.2, "featured" => false },
           "Limitless" => { "rating" => 9.2, "featured" => true },
-          "Hustle"    => { "rating" => 4.7, "featured" => true }
+          "Hustle"    => { "rating" => 4.7, "featured" => true },
         }
 
         results = @filter.where(hash, "featured", "true")
@@ -704,7 +722,7 @@ class TestFilters < JekyllUnitTest
         hash = {
           "The Words" => { "rating" => 1.2, "featured" => false },
           "Limitless" => { "rating" => 9.2, "featured" => true },
-          "Hustle"    => { "rating" => 4.7, "featured" => true }
+          "Hustle"    => { "rating" => 4.7, "featured" => true },
         }
 
         results = @filter.where_exp(hash, "item", "item.featured == true")
@@ -725,7 +743,7 @@ class TestFilters < JekyllUnitTest
         { "id" => "a", "groups" => [1, 2] },
         { "id" => "b", "groups" => [2, 3] },
         { "id" => "c" },
-        { "id" => "d", "groups" => [1, 3] }
+        { "id" => "d", "groups" => [1, 3] },
       ]
       should "filter with the contains operator over arrays" do
         results = @filter.where_exp(objects, "obj", "obj.groups contains 1")
@@ -807,7 +825,7 @@ class TestFilters < JekyllUnitTest
         items = [
           { "version"=>"1.0", "result"=>"slow" },
           { "version"=>"1.1.5", "result"=>"medium" },
-          { "version"=>"2.7.3", "result"=>"fast" }
+          { "version"=>"2.7.3", "result"=>"fast" },
         ]
 
         result = @filter.group_by_exp(items, "item", "item.version | split: '.' | first")
diff --git a/test/test_front_matter_defaults.rb b/test/test_front_matter_defaults.rb
index 30c713ac..0d066c11 100644
--- a/test/test_front_matter_defaults.rb
+++ b/test/test_front_matter_defaults.rb
@@ -7,12 +7,12 @@ class TestFrontMatterDefaults < JekyllUnitTest
         "defaults" => [{
           "scope"  => {
             "path" => "contacts",
-            "type" => "page"
+            "type" => "page",
           },
           "values" => {
-            "key" => "val"
-          }
-        }]
+            "key" => "val",
+          },
+        },],
       })
       @site.process
       @affected = @site.pages.find { |page| page.relative_path == "contacts/bar.html" }
@@ -30,12 +30,12 @@ class TestFrontMatterDefaults < JekyllUnitTest
       @site = fixture_site({
         "defaults" => [{
           "scope"  => {
-            "path" => "index.html"
+            "path" => "index.html",
           },
           "values" => {
-            "key" => "val"
-          }
-        }]
+            "key" => "val",
+          },
+        },],
       })
 
       @site.process
@@ -54,12 +54,12 @@ class TestFrontMatterDefaults < JekyllUnitTest
       @site = fixture_site({
         "defaults" => [{
           "scope"  => {
-            "path" => "win"
+            "path" => "win",
           },
           "values" => {
-            "key" => "val"
-          }
-        }]
+            "key" => "val",
+          },
+        },],
       })
 
       @site.process
@@ -78,12 +78,12 @@ class TestFrontMatterDefaults < JekyllUnitTest
       @site = fixture_site({
         "defaults" => [{
           "scope"  => {
-            "type" => "page"
+            "type" => "page",
           },
           "values" => {
-            "key" => "val"
-          }
-        }]
+            "key" => "val",
+          },
+        },],
       })
 
       @site.process
@@ -103,12 +103,12 @@ class TestFrontMatterDefaults < JekyllUnitTest
       @site = fixture_site({
         "defaults" => [{
           "scope"  => {
-            "type" => "pages"
+            "type" => "pages",
           },
           "values" => {
-            "key" => "val"
-          }
-        }]
+            "key" => "val",
+          },
+        },],
       })
       @site.process
       @affected = @site.pages
@@ -129,9 +129,9 @@ class TestFrontMatterDefaults < JekyllUnitTest
           "scope"  => {
           },
           "values" => {
-            "key" => "val"
-          }
-        }]
+            "key" => "val",
+          },
+        },],
       })
       @site.process
       @affected = @site.pages
@@ -149,9 +149,9 @@ class TestFrontMatterDefaults < JekyllUnitTest
       @site = fixture_site({
         "defaults" => [{
           "values" => {
-            "key" => "val"
-          }
-        }]
+            "key" => "val",
+          },
+        },],
       })
       @site.process
       @affected = @site.pages
@@ -171,9 +171,9 @@ class TestFrontMatterDefaults < JekyllUnitTest
         "destination" => dest_dir,
         "defaults"    => [{
           "values" => {
-            "date" => "2015-01-01 00:00:01"
-          }
-        }]
+            "date" => "2015-01-01 00:00:01",
+          },
+        },],
       }))
     end
 
diff --git a/test/test_kramdown.rb b/test/test_kramdown.rb
index 0a6332f8..d8f886a4 100644
--- a/test/test_kramdown.rb
+++ b/test/test_kramdown.rb
@@ -16,9 +16,9 @@ class TestKramdown < JekyllUnitTest
 
           "syntax_highlighter"      => "rouge",
           "syntax_highlighter_opts" => {
-            "bold_every" => 8, "css" => :class
-          }
-        }
+            "bold_every" => 8, "css" => :class,
+          },
+        },
       }
 
       @config = Jekyll.configuration(@config)
@@ -43,8 +43,8 @@ class TestKramdown < JekyllUnitTest
         override = {
           "highlighter" => nil,
           "kramdown"    => {
-            "smart_quotes" => "lsaquo,rsaquo,laquo,raquo"
-          }
+            "smart_quotes" => "lsaquo,rsaquo,laquo,raquo",
+          },
         }
 
         markdown = Converters::Markdown.new(Utils.deep_merge_hashes(@config, override))
@@ -70,8 +70,8 @@ class TestKramdown < JekyllUnitTest
           "highlighter" => nil,
           "markdown"    => "kramdown",
           "kramdown"    => {
-            "syntax_highlighter" => :coderay
-          }
+            "syntax_highlighter" => :coderay,
+          },
         }
 
         markdown = Converters::Markdown.new(Utils.deep_merge_hashes(@config, override))
@@ -89,8 +89,8 @@ class TestKramdown < JekyllUnitTest
         override = {
           "markdown" => "kramdown",
           "kramdown" => {
-            "enable_coderay" => true
-          }
+            "enable_coderay" => true,
+          },
         }
 
         @config.delete("highlighter")
@@ -115,9 +115,9 @@ class TestKramdown < JekyllUnitTest
         "kramdown"   => {
           "syntax_highlighter" => "coderay",
           "coderay"            => {
-            "hello" => "world"
-          }
-        }
+            "hello" => "world",
+          },
+        },
       }))
 
       expect(Kramdown::Document).to receive(:new) do |arg1, hash|
diff --git a/test/test_layout_reader.rb b/test/test_layout_reader.rb
index 133cd6f2..1d32fa57 100644
--- a/test/test_layout_reader.rb
+++ b/test/test_layout_reader.rb
@@ -4,7 +4,7 @@ class TestLayoutReader < JekyllUnitTest
   context "reading layouts" do
     setup do
       config = Jekyll::Configuration::DEFAULTS.merge({ "source"      => source_dir,
-                                                       "destination" => dest_dir })
+                                                       "destination" => dest_dir, })
       @site = fixture_site(config)
     end
 
diff --git a/test/test_liquid_renderer.rb b/test/test_liquid_renderer.rb
index 7d429c52..6ba29299 100644
--- a/test/test_liquid_renderer.rb
+++ b/test/test_liquid_renderer.rb
@@ -16,7 +16,7 @@ class TestLiquidRenderer < JekyllUnitTest
       expected = [
         %r!^Filename\s+|\s+Count\s+|\s+Bytes\s+|\s+Time$!,
         %r!^-+\++-+\++-+\++-+$!,
-        %r!^_posts/2010-01-09-date-override\.markdown\s+|\s+\d+\s+|\s+\d+\.\d{2}K\s+|\s+\d+\.\d{3}$!
+        %r!^_posts/2010-01-09-date-override\.markdown\s+|\s+\d+\s+|\s+\d+\.\d{2}K\s+|\s+\d+\.\d{3}$!,
       ]
       # rubocop:enable Metrics/LineLength
 
diff --git a/test/test_new_command.rb b/test/test_new_command.rb
index 982de1da..a02f1565 100644
--- a/test/test_new_command.rb
+++ b/test/test_new_command.rb
@@ -25,14 +25,14 @@ class TestNewCommand < JekyllUnitTest
 
     should "create a new directory" do
       refute_exist @full_path
-      Jekyll::Commands::New.process(@args)
+      capture_output { Jekyll::Commands::New.process(@args) }
       assert_exist @full_path
     end
 
     should "create a Gemfile" do
       gemfile = File.join(@full_path, "Gemfile")
       refute_exist @full_path
-      capture_stdout { Jekyll::Commands::New.process(@args) }
+      capture_output { Jekyll::Commands::New.process(@args) }
       assert_exist gemfile
       assert_match(%r!gem "jekyll", "#{Jekyll::VERSION}"!, File.read(gemfile))
       assert_match(%r!gem "github-pages"!, File.read(gemfile))
@@ -40,12 +40,11 @@ class TestNewCommand < JekyllUnitTest
 
     should "display a success message" do
       Jekyll::Commands::New.process(@args)
-      output = Jekyll.logger.messages[-3]
-      output_last = Jekyll.logger.messages.last
-      success_message = "New jekyll site installed in #{@full_path.cyan}."
-      bundle_message = "Running bundle install in #{@full_path.cyan}..."
+      output = Jekyll.logger.messages
+      success_message = "New jekyll site installed in #{@full_path.cyan}. "
+      bundle_message = "Running bundle install in #{@full_path.cyan}... "
       assert_includes output, success_message
-      assert_includes output_last, bundle_message
+      assert_includes output, bundle_message
     end
 
     should "copy the static files in site template to the new directory" do
@@ -54,7 +53,7 @@ class TestNewCommand < JekyllUnitTest
       end
       static_template_files << "/Gemfile"
 
-      capture_stdout { Jekyll::Commands::New.process(@args) }
+      capture_output { Jekyll::Commands::New.process(@args) }
 
       new_site_files = dir_contents(@full_path).reject do |f|
         File.extname(f) == ".markdown"
@@ -76,7 +75,7 @@ class TestNewCommand < JekyllUnitTest
         f.gsub! "0000-00-00", stubbed_date
       end
 
-      capture_stdout { Jekyll::Commands::New.process(@args) }
+      capture_output { Jekyll::Commands::New.process(@args) }
 
       new_site_files = dir_contents(@full_path).select do |f|
         erb_template_files.include? f
@@ -87,7 +86,7 @@ class TestNewCommand < JekyllUnitTest
 
     should "create blank project" do
       blank_contents = %w(/_drafts /_layouts /_posts /index.html)
-      capture_stdout { Jekyll::Commands::New.process(@args, "--blank") }
+      capture_output { Jekyll::Commands::New.process(@args, "--blank") }
       output = Jekyll.logger.messages.last
       bundle_message = "Running bundle install in #{@full_path.cyan}..."
       assert_same_elements blank_contents, dir_contents(@full_path)
@@ -95,13 +94,13 @@ class TestNewCommand < JekyllUnitTest
     end
 
     should "force created folder" do
-      capture_stdout { Jekyll::Commands::New.process(@args) }
-      output = capture_stdout { Jekyll::Commands::New.process(@args, "--force") }
+      capture_output { Jekyll::Commands::New.process(@args) }
+      output = capture_output { Jekyll::Commands::New.process(@args, "--force") }
       assert_match(%r!New jekyll site installed in!, output)
     end
 
     should "skip bundle install when opted to" do
-      capture_stdout { Jekyll::Commands::New.process(@args, "--skip-bundle") }
+      capture_output { Jekyll::Commands::New.process(@args, "--skip-bundle") }
       output = Jekyll.logger.messages.last
       bundle_message = "Bundle install skipped."
       assert_includes output, bundle_message
@@ -120,7 +119,7 @@ class TestNewCommand < JekyllUnitTest
 
     should "create a new directory" do
       refute_exist @site_name_with_spaces
-      capture_stdout { Jekyll::Commands::New.process(@multiple_args) }
+      capture_output { Jekyll::Commands::New.process(@multiple_args) }
       assert_exist @site_name_with_spaces
     end
   end
diff --git a/test/test_page.rb b/test/test_page.rb
index 259de185..431c57a6 100644
--- a/test/test_page.rb
+++ b/test/test_page.rb
@@ -12,7 +12,7 @@ class TestPage < JekyllUnitTest
 
   def do_render(page)
     layouts = {
-      "default" => Layout.new(@site, source_dir("_layouts"), "simple.html")
+      "default" => Layout.new(@site, source_dir("_layouts"), "simple.html"),
     }
     page.render(layouts, @site.site_payload)
   end
@@ -23,7 +23,7 @@ class TestPage < JekyllUnitTest
       @site = Site.new(Jekyll.configuration({
         "source"            => source_dir,
         "destination"       => dest_dir,
-        "skip_config_files" => true
+        "skip_config_files" => true,
       }))
     end
 
@@ -90,7 +90,7 @@ class TestPage < JekyllUnitTest
           :permalink => "/properties/",
           :published => nil,
           :title     => "Properties Page",
-          :url       => "/properties/"
+          :url       => "/properties/",
         }
 
         attrs.each do |attr, val|
diff --git a/test/test_plugin_manager.rb b/test/test_plugin_manager.rb
index c625c3a8..702df593 100644
--- a/test/test_plugin_manager.rb
+++ b/test/test_plugin_manager.rb
@@ -68,7 +68,7 @@ class TestPluginManager < JekyllUnitTest
     should "require plugin files" do
       site = double({ :safe          => false,
                       :config        => { "plugins_dir" => "_plugins" },
-                      :in_source_dir => "/tmp/" })
+                      :in_source_dir => "/tmp/", })
       plugin_manager = PluginManager.new(site)
 
       expect(Jekyll::External).to receive(:require_with_graceful_fail)
@@ -98,9 +98,9 @@ class TestPluginManager < JekyllUnitTest
     should "call site's in_source_dir" do
       site = double({
         :config        => {
-          "plugins_dir" => Jekyll::Configuration::DEFAULTS["plugins_dir"]
+          "plugins_dir" => Jekyll::Configuration::DEFAULTS["plugins_dir"],
         },
-        :in_source_dir => "/tmp/"
+        :in_source_dir => "/tmp/",
       })
       plugin_manager = PluginManager.new(site)
 
@@ -132,7 +132,7 @@ class TestPluginManager < JekyllUnitTest
 
     should "print no deprecation warning if jekyll-paginate is present" do
       site = double({
-        :config => { "paginate" => true, "gems" => ["jekyll-paginate"] }
+        :config => { "paginate" => true, "gems" => ["jekyll-paginate"] },
       })
       plugin_manager = PluginManager.new(site)
 
diff --git a/test/test_rdiscount.rb b/test/test_rdiscount.rb
index 9390aaed..32289a64 100644
--- a/test/test_rdiscount.rb
+++ b/test/test_rdiscount.rb
@@ -13,8 +13,8 @@ class TestRdiscount < JekyllUnitTest
         "markdown"  => "rdiscount",
         "rdiscount" => {
           "toc_token"  => "{:toc}",
-          "extensions" => %w(smart generate_toc)
-        }
+          "extensions" => %w(smart generate_toc),
+        },
       }
 
       @markdown = Converters::Markdown.new config
diff --git a/test/test_redcarpet.rb b/test/test_redcarpet.rb
index 140fabbe..4e979f4d 100644
--- a/test/test_redcarpet.rb
+++ b/test/test_redcarpet.rb
@@ -12,8 +12,8 @@ class TestRedcarpet < JekyllUnitTest
       @config = {
         "markdown"  => "redcarpet",
         "redcarpet" => {
-          "extensions" => %w(smart strikethrough filter_html)
-        }
+          "extensions" => %w(smart strikethrough filter_html),
+        },
       }
 
       @markdown = Converters::Markdown.new @config
diff --git a/test/test_regenerator.rb b/test/test_regenerator.rb
index 03920c83..9e1559d4 100644
--- a/test/test_regenerator.rb
+++ b/test/test_regenerator.rb
@@ -8,10 +8,10 @@ class TestRegenerator < JekyllUnitTest
       @site = fixture_site({
         "collections" => {
           "methods" => {
-            "output" => true
-          }
+            "output" => true,
+          },
         },
-        "incremental" => true
+        "incremental" => true,
       })
 
       @site.read
@@ -92,7 +92,7 @@ class TestRegenerator < JekyllUnitTest
     setup do
       FileUtils.rm_rf(source_dir(".jekyll-metadata"))
       @site = fixture_site({
-        "incremental" => true
+        "incremental" => true,
       })
 
       @site.read
@@ -129,7 +129,7 @@ class TestRegenerator < JekyllUnitTest
       @site = Site.new(Jekyll.configuration({
         "source"      => source_dir,
         "destination" => dest_dir,
-        "incremental" => true
+        "incremental" => true,
       }))
 
       @site.process
@@ -311,7 +311,7 @@ class TestRegenerator < JekyllUnitTest
       @site = Site.new(Jekyll.configuration({
         "source"      => source_dir,
         "destination" => dest_dir,
-        "incremental" => false
+        "incremental" => false,
       }))
 
       @site.process
diff --git a/test/test_related_posts.rb b/test/test_related_posts.rb
index ef7265ef..2d616550 100644
--- a/test/test_related_posts.rb
+++ b/test/test_related_posts.rb
@@ -28,7 +28,7 @@ class TestRelatedPosts < JekyllUnitTest
 
       allow_any_instance_of(Jekyll::RelatedPosts).to receive(:display)
       @site = fixture_site({
-        "lsi" => true
+        "lsi" => true,
       })
 
       @site.reset
diff --git a/test/test_sass.rb b/test/test_sass.rb
index f5241790..3a9df0ae 100644
--- a/test/test_sass.rb
+++ b/test/test_sass.rb
@@ -5,7 +5,7 @@ class TestSass < JekyllUnitTest
     setup do
       @site = Jekyll::Site.new(Jekyll.configuration({
         "source"      => source_dir,
-        "destination" => dest_dir
+        "destination" => dest_dir,
       }))
       @site.process
       @test_css_file = dest_dir("css/main.css")
diff --git a/test/test_site.rb b/test/test_site.rb
index 81da363d..65032ebd 100644
--- a/test/test_site.rb
+++ b/test/test_site.rb
@@ -20,7 +20,7 @@ class TestSite < JekyllUnitTest
 
     should "have an array for plugins if passed as an array" do
       site = Site.new(site_configuration({
-        "plugins_dir" => ["/tmp/plugins", "/tmp/otherplugins"]
+        "plugins_dir" => ["/tmp/plugins", "/tmp/otherplugins"],
       }))
       array = if Utils::Platforms.windows?
                 ["C:/tmp/plugins", "C:/tmp/otherplugins"]
@@ -49,6 +49,18 @@ class TestSite < JekyllUnitTest
       site = Site.new(site_configuration({ "baseurl" => "/blog" }))
       assert_equal "/blog", site.baseurl
     end
+
+    should "only include theme includes_path if the path exists" do
+      site = fixture_site({ "theme" => "test-theme" })
+      assert_equal [source_dir("_includes"), theme_dir("_includes")],
+        site.includes_load_paths
+
+      allow(File).to receive(:directory?).with(theme_dir("_sass")).and_return(true)
+      allow(File).to receive(:directory?).with(theme_dir("_layouts")).and_return(true)
+      allow(File).to receive(:directory?).with(theme_dir("_includes")).and_return(false)
+      site = fixture_site({ "theme" => "test-theme" })
+      assert_equal [source_dir("_includes")], site.includes_load_paths
+    end
   end
   context "creating sites" do
     setup do
@@ -485,7 +497,7 @@ class TestSite < JekyllUnitTest
     context "manipulating the Jekyll environment" do
       setup do
         @site = Site.new(site_configuration({
-          "incremental" => false
+          "incremental" => false,
         }))
         @site.process
         @page = @site.pages.find { |p| p.name == "environment.html" }
@@ -499,7 +511,7 @@ class TestSite < JekyllUnitTest
         setup do
           ENV["JEKYLL_ENV"] = "production"
           @site = Site.new(site_configuration({
-            "incremental" => false
+            "incremental" => false,
           }))
           @site.process
           @page = @site.pages.find { |p| p.name == "environment.html" }
@@ -565,7 +577,7 @@ class TestSite < JekyllUnitTest
     context "incremental build" do
       setup do
         @site = Site.new(site_configuration({
-          "incremental" => true
+          "incremental" => true,
         }))
         @site.read
       end
diff --git a/test/test_static_file.rb b/test/test_static_file.rb
index 2be800a6..114885db 100644
--- a/test/test_static_file.rb
+++ b/test/test_static_file.rb
@@ -16,33 +16,34 @@ class TestStaticFile < JekyllUnitTest
   end
 
   def setup_static_file(base, dir, name)
-    StaticFile.new(@site, base, dir, name)
+    Dir.chdir(@site.source) { StaticFile.new(@site, base, dir, name) }
   end
 
   def setup_static_file_with_collection(base, dir, name, metadata)
     site = fixture_site("collections" => { "foo" => metadata })
-    StaticFile.new(site, base, dir, name, site.collections["foo"])
+    Dir.chdir(site.source) do
+      StaticFile.new(site, base, dir, name, site.collections["foo"])
+    end
   end
 
   def setup_static_file_with_defaults(base, dir, name, defaults)
     site = fixture_site("defaults" => defaults)
-    StaticFile.new(site, base, dir, name)
+    Dir.chdir(site.source) do
+      StaticFile.new(site, base, dir, name)
+    end
   end
 
   context "A StaticFile" do
     setup do
       clear_dest
-      @old_pwd = Dir.pwd
-      Dir.chdir source_dir
       @site = fixture_site
       @filename = "static_file.txt"
       make_dummy_file(@filename)
-      @static_file = setup_static_file(nil, nil, @filename)
+      @static_file = setup_static_file(@site.source, "", @filename)
     end
 
     teardown do
       remove_dummy_file(@filename) if File.exist?(source_dir(@filename))
-      Dir.chdir @old_pwd
     end
 
     should "have a source file path" do
@@ -95,8 +96,8 @@ class TestStaticFile < JekyllUnitTest
     should "use the _config.yml defaults to determine writability" do
       defaults = [{
         "scope"  => { "path" => "private" },
-        "values" => { "published" => false }
-      }]
+        "values" => { "published" => false },
+      },]
       static_file = setup_static_file_with_defaults(
         "root",
         "private/dir/subdir",
@@ -146,7 +147,7 @@ class TestStaticFile < JekyllUnitTest
         "name"          => "static_file.txt",
         "extname"       => ".txt",
         "modified_time" => @static_file.modified_time,
-        "path"          => "/static_file.txt"
+        "path"          => "/static_file.txt",
       }
       assert_equal expected, @static_file.to_liquid
     end
diff --git a/test/test_tags.rb b/test/test_tags.rb
index fd6dcb97..a636abf6 100644
--- a/test/test_tags.rb
+++ b/test/test_tags.rb
@@ -17,7 +17,7 @@ class TestTags < JekyllUnitTest
     info = { :filters => [Jekyll::Filters], :registers => { :site => site } }
     @converter = site.converters.find { |c| c.class == converter_class }
     payload = { "highlighter_prefix" => @converter.highlighter_prefix,
-                "highlighter_suffix" => @converter.highlighter_suffix }
+                "highlighter_suffix" => @converter.highlighter_suffix, }
 
     @result = Liquid::Template.parse(content).render!(payload, info)
     @result = @converter.convert(@result)
@@ -487,7 +487,7 @@ CONTENT
         end
 
         create_post(@content, {
-          "markdown" => "rdiscount"
+          "markdown" => "rdiscount",
         })
       end
 
@@ -517,7 +517,7 @@ CONTENT
         end
 
         create_post(@content, {
-          "markdown" => "redcarpet"
+          "markdown" => "redcarpet",
         })
       end
 
@@ -541,7 +541,7 @@ CONTENT
         "permalink"   => "pretty",
         "source"      => source_dir,
         "destination" => dest_dir,
-        "read_posts"  => true
+        "read_posts"  => true,
       })
     end
 
@@ -567,7 +567,7 @@ CONTENT
         "permalink"   => "pretty",
         "source"      => source_dir,
         "destination" => dest_dir,
-        "read_posts"  => true
+        "read_posts"  => true,
       })
     end
 
@@ -596,7 +596,7 @@ CONTENT
         "permalink"   => "pretty",
         "source"      => source_dir,
         "destination" => dest_dir,
-        "read_posts"  => true
+        "read_posts"  => true,
       })
     end
 
@@ -628,7 +628,7 @@ CONTENT
         "permalink"   => "pretty",
         "source"      => source_dir,
         "destination" => dest_dir,
-        "read_posts"  => true
+        "read_posts"  => true,
       })
     end
 
@@ -664,7 +664,7 @@ CONTENT
           "permalink"   => "pretty",
           "source"      => source_dir,
           "destination" => dest_dir,
-          "read_posts"  => true
+          "read_posts"  => true,
         })
       end
     end
@@ -683,7 +683,7 @@ CONTENT
           "permalink"   => "pretty",
           "source"      => source_dir,
           "destination" => dest_dir,
-          "read_posts"  => true
+          "read_posts"  => true,
         })
       end
     end
@@ -703,7 +703,7 @@ CONTENT
       create_post(content, {
         "source"      => source_dir,
         "destination" => dest_dir,
-        "read_all"    => true
+        "read_all"    => true,
       })
     end
 
@@ -737,7 +737,7 @@ CONTENT
         "source"           => source_dir,
         "destination"      => dest_dir,
         "collections"      => { "methods" => { "output" => true } },
-        "read_collections" => true
+        "read_collections" => true,
       })
     end
 
@@ -764,7 +764,7 @@ CONTENT
         "source"           => source_dir,
         "destination"      => dest_dir,
         "collections"      => { "methods" => { "output" => true } },
-        "read_collections" => true
+        "read_collections" => true,
       })
     end
 
@@ -796,7 +796,7 @@ CONTENT
           "source"           => source_dir,
           "destination"      => dest_dir,
           "collections"      => { "methods" => { "output" => true } },
-          "read_collections" => true
+          "read_collections" => true,
         })
       end
     end
@@ -820,7 +820,7 @@ CONTENT
             "source"      => source_dir,
             "destination" => dest_dir,
             "read_posts"  => true,
-            "safe"        => true
+            "safe"        => true,
           })
         end
         @result ||= ""
@@ -842,7 +842,7 @@ CONTENT
             "source"      => source_dir,
             "destination" => dest_dir,
             "read_posts"  => true,
-            "safe"        => true
+            "safe"        => true,
           })
         end
         assert_match(
@@ -868,7 +868,7 @@ CONTENT
           "permalink"   => "pretty",
           "source"      => source_dir,
           "destination" => dest_dir,
-          "read_posts"  => true
+          "read_posts"  => true,
         })
       end
 
@@ -896,7 +896,7 @@ CONTENT
             "permalink"   => "pretty",
             "source"      => source_dir,
             "destination" => dest_dir,
-            "read_posts"  => true
+            "read_posts"  => true,
           })
         end
 
@@ -913,7 +913,7 @@ CONTENT
             "permalink"   => "pretty",
             "source"      => source_dir,
             "destination" => dest_dir,
-            "read_posts"  => true
+            "read_posts"  => true,
           })
         end
       end
@@ -932,7 +932,7 @@ CONTENT
           "permalink"   => "pretty",
           "source"      => source_dir,
           "destination" => dest_dir,
-          "read_posts"  => true
+          "read_posts"  => true,
         })
       end
 
@@ -959,7 +959,7 @@ CONTENT
           "permalink"   => "pretty",
           "source"      => source_dir,
           "destination" => dest_dir,
-          "read_posts"  => true
+          "read_posts"  => true,
         })
       end
 
@@ -982,7 +982,7 @@ CONTENT
           "permalink"    => "pretty",
           "source"       => source_dir,
           "destination"  => dest_dir,
-          "read_posts"   => true
+          "read_posts"   => true,
         })
       end
 
@@ -1004,7 +1004,7 @@ CONTENT
           "permalink"   => "pretty",
           "source"      => source_dir,
           "destination" => dest_dir,
-          "read_posts"  => true
+          "read_posts"  => true,
         })
       end
 
@@ -1030,7 +1030,7 @@ CONTENT
             "permalink"   => "pretty",
             "source"      => source_dir,
             "destination" => dest_dir,
-            "read_posts"  => true
+            "read_posts"  => true,
           })
         end
         assert_match(
@@ -1125,7 +1125,7 @@ CONTENT
               "permalink"   => "pretty",
               "source"      => source_dir,
               "destination" => dest_dir,
-              "read_posts"  => true
+              "read_posts"  => true,
             })
           end
           assert_match "Could not locate the included file 'missing.html' in any of " \
@@ -1150,7 +1150,7 @@ CONTENT
               "permalink"   => "pretty",
               "source"      => source_dir,
               "destination" => dest_dir,
-              "read_posts"  => true
+              "read_posts"  => true,
             })
           end
           assert_equal(
@@ -1180,7 +1180,7 @@ CONTENT
             "source"      => source_dir,
             "destination" => dest_dir,
             "read_posts"  => true,
-            "safe"        => true
+            "safe"        => true,
           })
         end
         @result ||= ""
@@ -1202,7 +1202,7 @@ CONTENT
             "source"      => source_dir,
             "destination" => dest_dir,
             "read_posts"  => true,
-            "safe"        => true
+            "safe"        => true,
           })
         end
         assert_match(
diff --git a/test/test_theme.rb b/test/test_theme.rb
index ab1eff43..3d557dc8 100644
--- a/test/test_theme.rb
+++ b/test/test_theme.rb
@@ -3,7 +3,6 @@ require "helper"
 class TestTheme < JekyllUnitTest
   def setup
     @theme = Theme.new("test-theme")
-    @expected_root = File.expand_path "./fixtures/test-theme", File.dirname(__FILE__)
   end
 
   context "initializing" do
@@ -13,7 +12,7 @@ class TestTheme < JekyllUnitTest
     end
 
     should "know the theme root" do
-      assert_equal @expected_root, @theme.root
+      assert_equal theme_dir, @theme.root
     end
 
     should "know the theme version" do
@@ -36,13 +35,13 @@ class TestTheme < JekyllUnitTest
   context "path generation" do
     [:assets, :_layouts, :_includes, :_sass].each do |folder|
       should "know the #{folder} path" do
-        expected = File.expand_path(folder.to_s, @expected_root)
+        expected = theme_dir(folder.to_s)
         assert_equal expected, @theme.public_send("#{folder.to_s.tr("_", "")}_path")
       end
     end
 
     should "generate folder paths" do
-      expected = File.expand_path("./_sass", @expected_root)
+      expected = theme_dir("_sass")
       assert_equal expected, @theme.send(:path_for, :_sass)
     end
 
@@ -58,7 +57,7 @@ class TestTheme < JekyllUnitTest
       # no support for symlinks on Windows
       skip_if_windows "Jekyll does not currently support symlinks on Windows."
 
-      expected = File.expand_path("./_layouts", @expected_root)
+      expected = theme_dir("_layouts")
       assert_equal expected, @theme.send(:path_for, :_symlink)
     end
   end