Respect absolute paths in compute_source_path.

When using compute_source_path to determine the full path of an
asset, if our source begins with '/', we don't want to include
the directory. Examples are illustrative:

> compute_source_path("foo", "stylesheets", "css")
=> "/Users/steve/src/my_app/public/stylesheets/foo.css"
> compute_source_path("/foo", "stylesheets", "css")
=> "/Users/steve/src/my_app/public/foo.css"

Before this patch, the second example would return the same as the
first.

Fixes #5680.

2 files changed, 14 insertions, 3 deletions

diff --git a/actionpack/test/fixtures/public/foo/baz.css b/actionpack/test/fixtures/public/foo/baz.css
new file mode 100644
index 0000000000..b5173fbef2
--- /dev/null
+++ b/actionpack/test/fixtures/public/foo/baz.css
@@ -0,0 +1,3 @@
+body {
+background: #000;
+}
diff --git a/actionpack/test/template/asset_tag_helper_test.rb b/actionpack/test/template/asset_tag_helper_test.rb
index 7cc567c72d..bcc55189b9 100644
--- a/actionpack/test/template/asset_tag_helper_test.rb
+++ b/actionpack/test/template/asset_tag_helper_test.rb
@@ -1267,9 +1267,6 @@ class AssetTagHelperTest < ActionView::TestCase
     assert !File.exist?(File.join(ActionView::Helpers::AssetTagHelper::STYLESHEETS_DIR, 'money.css'))
   end
 
-
-
-
   def test_caching_stylesheet_include_tag_when_caching_off
     ENV["RAILS_ASSET_ID"] = ""
     config.perform_caching = false
@@ -1298,6 +1295,17 @@ class AssetTagHelperTest < ActionView::TestCase
 
     assert !File.exist?(File.join(ActionView::Helpers::AssetTagHelper::STYLESHEETS_DIR, 'money.css'))
   end
+
+  def test_caching_stylesheet_include_tag_with_absolute_uri
+    ENV["RAILS_ASSET_ID"] = ""
+
+    assert_dom_equal(
+      %(<link href="/stylesheets/all.css" media="screen" rel="stylesheet" />),
+      stylesheet_link_tag("/foo/baz", :cache => true)
+    )
+
+    FileUtils.rm(File.join(ActionView::Helpers::AssetTagHelper::STYLESHEETS_DIR, 'all.css'))
+  end
 end
 
 class AssetTagHelperNonVhostTest < ActionView::TestCase