Feat: drop ruby 2.3 (#7454)

Merge pull request 7454

.travis.yml

@@ -5,9 +5,8 @@ language: ruby
 
 rvm:
   - &ruby1 2.6.0
-  - &ruby2 2.5.3
-  - &ruby3 2.3.8
-  - &jruby jruby-9.1.16.0
+  - &ruby2 2.4.5
+  - &jruby jruby-9.2.6.0
 
 matrix:
   include:

appveyor.yml

@@ -21,12 +21,8 @@ environment:
       TEST_SUITE: "default-site"
     - RUBY_FOLDER_VER: "26"
       TEST_SUITE: "profile-docs"
-    - RUBY_FOLDER_VER: "25"
-      TEST_SUITE: "test"
     - RUBY_FOLDER_VER: "24"
       TEST_SUITE: "test"
-    - RUBY_FOLDER_VER: "23"
-      TEST_SUITE: "test"
 
 install:
   - SET PATH=C:\Ruby%RUBY_FOLDER_VER%-x64\bin;%PATH%

jekyll.gemspec

@@ -30,7 +30,7 @@ Gem::Specification.new do |s|
   s.rdoc_options     = ["--charset=UTF-8"]
   s.extra_rdoc_files = %w(README.markdown LICENSE)
 
-  s.required_ruby_version     = ">= 2.3.0"
+  s.required_ruby_version     = ">= 2.4.0"
   s.required_rubygems_version = ">= 2.7.0"
 
   s.add_runtime_dependency("addressable",           "~> 2.4")

test/test_commands_serve.rb

@@ -43,6 +43,9 @@ class TestCommandsServe < JekyllUnitTest
 
   context "using LiveReload" do
     setup do
+      skip_if_windows "EventMachine support on Windows is limited"
+      skip("Refinements are not fully supported in JRuby") if jruby?
+
       @temp_dir = Dir.mktmpdir("jekyll_livereload_test")
       @destination = File.join(@temp_dir, "_site")
       Dir.mkdir(@destination) || flunk("Could not make directory #{@destination}")
@@ -93,7 +96,6 @@ class TestCommandsServe < JekyllUnitTest
     end
 
     should "serve livereload.js over HTTP on the default LiveReload port" do
-      skip_if_windows "EventMachine support on Windows is limited"
       opts = serve(@standard_options)
       content = @client.get_content(
         "http://#{opts["host"]}:#{opts["livereload_port"]}/livereload.js"
@@ -102,7 +104,6 @@ class TestCommandsServe < JekyllUnitTest
     end
 
     should "serve nothing else over HTTP on the default LiveReload port" do
-      skip_if_windows "EventMachine support on Windows is limited"
       opts = serve(@standard_options)
       res = @client.get("http://#{opts["host"]}:#{opts["livereload_port"]}/")
       assert_equal(400, res.status_code)
@@ -110,7 +111,6 @@ class TestCommandsServe < JekyllUnitTest
     end
 
     should "insert the LiveReload script tags" do
-      skip_if_windows "EventMachine support on Windows is limited"
       opts = serve(@standard_options)
       content = @client.get_content(
         "http://#{opts["host"]}:#{opts["port"]}/#{opts["baseurl"]}/hello.html"
@@ -123,7 +123,6 @@ class TestCommandsServe < JekyllUnitTest
     end
 
     should "apply the max and min delay options" do
-      skip_if_windows "EventMachine support on Windows is limited"
       opts = serve(@standard_options.merge(
                      "livereload_max_delay" => "1066",
                      "livereload_min_delay" => "3"