Add option to strip trailing newlines from ERB templates

Add failing test for views with trailing newlines

Add and test config option

Move config option to config/application.rb

Move implementation to ERB template handler

Move config option to ActionView::Template::Handlers::ERB

actionview/lib/action_view/template/handlers/erb.rb

@@ -16,6 +16,9 @@ module ActionView
         # Do not escape templates of these mime types.
         class_attribute :escape_ignore_list, default: ["text/plain"]
 
+        # Strip trailing newlines from rendered output
+        class_attribute :strip_trailing_newlines, default: false
+
         ENCODING_TAG = Regexp.new("\\A(<%#{ENCODING_FLAG}-?%>)[ \\t]*")
 
         def self.call(template, source)
@@ -45,6 +48,9 @@ module ActionView
           # Always make sure we return a String in the default_internal
           erb.encode!
 
+          # Strip trailing newlines from the template if enabled
+          erb.chomp! if strip_trailing_newlines
+
           options = {
             escape: (self.class.escape_ignore_list.include? template.type),
             trim: (self.class.erb_trim_mode == "-")

actionview/test/actionpack/abstract/abstract_controller_test.rb

@@ -52,6 +52,10 @@ module AbstractController
         render "index.erb"
       end
 
+      def with_final_newline
+        render "with_final_newline.erb"
+      end
+
       def index_to_string
         self.response_body = render_to_string "index"
       end
@@ -84,6 +88,14 @@ module AbstractController
         assert_equal "Hello from index.erb", @controller.response_body
       end
 
+      test "stripping final newline works" do
+        ActionView::Template::Handlers::ERB.strip_trailing_newlines = true
+        @controller.process(:with_final_newline)
+        assert_equal "Hello from with_final_newline.erb", @controller.response_body
+      ensure
+        ActionView::Template::Handlers::ERB.strip_trailing_newlines = false
+      end
+
       test "render_to_string works with a String as an argument" do
         @controller.process(:index_to_string)
         assert_equal "Hello from index.erb", @controller.response_body

actionview/test/actionpack/abstract/views/with_final_newline.erb

@@ -0,0 +1 @@
+Hello from with_final_newline.erb