Fix #3653: Add a doctor helper to test pwd's.

lib/jekyll/commands/doctor.rb

@@ -30,6 +30,7 @@ module Jekyll
 
         def healthy?(site)
           [
+            fsnotify_buggy?(site),
             !deprecated_relative_permalinks(site),
             !conflicting_urls(site)
           ].all?
@@ -59,8 +60,23 @@ module Jekyll
           conflicting_urls
         end
 
-        private
+        def fsnotify_buggy?(site)
+          return true if !Utils::Platforms.osx?
+          if Dir.pwd != `pwd`.strip
+            Jekyll.logger.error "  " + <<-STR.strip.gsub(/\n\s+/, "\n  ")
+              We have detected that there might be trouble using fsevent on your
+              operating system, you can read https://github.com/thibaudgg/rb-fsevent/wiki/no-fsevents-fired-(OSX-bug)
+              for possible work arounds or you can work around it immediately
+              with `--force-polling`.
+            STR
 
+            false
+          end
+
+          true
+        end
+
+        private
         def collect_urls(urls, things, destination)
           things.each do |thing|
             dest = thing.destination(destination)

lib/jekyll/utils.rb

@@ -1,6 +1,6 @@
 module Jekyll
-  module Utils
+  module Utils extend self
-    extend self
+    autoload :Platforms, 'jekyll/utils/platforms'
 
     # Constants for use in #slugify
     SLUGIFY_MODES = %w{raw default pretty}

lib/jekyll/utils/platforms.rb

@@ -0,0 +1,30 @@
+module Jekyll
+  module Utils
+    module Platforms extend self
+
+      # Provides jruby? and mri? which respectively detect these two types of
+      # tested Engines we support, in the future we might probably support the
+      # other one that everyone used to talk about.
+
+      { :jruby? => "jruby", :mri? => "ruby" }.each do |k, v|
+        define_method k do
+          ::RUBY_ENGINE == v
+        end
+      end
+
+      # Provides windows?, linux?, osx?, unix? so that we can detect
+      # platforms. This is mostly useful for `jekyll doctor` and for testing
+      # where we kick off certain tests based on the platform.
+
+      { :windows? => /mswin|mingw|cygwin/, :linux? => /linux/, \
+          :osx? => /darwin|mac os/, :unix? => /solaris|bsd/ }.each do |k, v|
+
+        define_method k do
+          !!(
+            RbConfig::CONFIG["host_os"] =~ v
+          )
+        end
+      end
+    end
+  end
+end