Merge pull request #8756 from causes/js_include_tag_fix

Fix javascript_include_tag when no js runtime is available

3 files changed, 28 insertions, 9 deletions

diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index b887a5837a..faa33f2992 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -6,6 +6,11 @@
 
 *   Do not append second slash to `root_url` when using `trailing_slash: true`
 
+*   Prevent unnecessary asset compilation when using javascript_include_tag on
+    files with non-standard extensions.
+
+    *Noah Silas*
+
 *   Do not append second slash to root_url when using `trailing_slash: true`
 
     Fix #8700.
diff --git a/actionpack/lib/sprockets/helpers/rails_helper.rb b/actionpack/lib/sprockets/helpers/rails_helper.rb
index bc573d8640..51f0cbb2da 100644
--- a/actionpack/lib/sprockets/helpers/rails_helper.rb
+++ b/actionpack/lib/sprockets/helpers/rails_helper.rb
@@ -157,18 +157,25 @@ module Sprockets
         end
 
         def rewrite_extension(source, dir, ext)
-          source_ext = File.extname(source)
-          if ext && source_ext != ".#{ext}"
-            if !source_ext.empty? && (asset = asset_environment[source]) &&
-                  asset.pathname.to_s =~ /#{source}\Z/
-              source
-            else
-              "#{source}.#{ext}"
-            end
-          else
+          source_ext = File.extname(source)[1..-1]
+
+          if !ext || ext == source_ext
+            source
+          elsif source_ext.blank?
+            "#{source}.#{ext}"
+          elsif exact_match_present?(source)
             source
+          else
+            "#{source}.#{ext}"
           end
         end
+
+        def exact_match_present?(source)
+          pathname = asset_environment.resolve(source)
+          pathname.to_s =~ /#{Regexp.escape(source)}\Z/
+        rescue Sprockets::FileNotFound
+          false
+        end
       end
     end
   end
diff --git a/actionpack/test/template/sprockets_helper_test.rb b/actionpack/test/template/sprockets_helper_test.rb
index 01dd66aa1f..93832c7bd9 100644
--- a/actionpack/test/template/sprockets_helper_test.rb
+++ b/actionpack/test/template/sprockets_helper_test.rb
@@ -270,6 +270,13 @@ class SprocketsHelperTest < ActionView::TestCase
       javascript_include_tag(:application, :extra)
   end
 
+  test "precompiled assets with an extension when no JS runtime is available" do
+    @config.assets.compile = false
+    @config.assets.digests = {'foo.min.js' => 'foo.min-f00.js'}
+    Sprockets::Index.any_instance.stubs(:build_asset).raises
+    assert_nothing_raised { javascript_include_tag('foo.min') }
+  end
+
   test "stylesheet path through asset_path" do
     assert_match %r{/assets/application-[0-9a-f]+.css}, asset_path(:application, :ext => "css")