Use Redis for CacheMarkDownField on non AR models

This allows using `CacheMarkdownField` for models that are not backed
by ActiveRecord.

When the including class inherits `ActiveRecord::Base` we include
`Gitlab::MarkdownCache::ActiveRecord::Extension`. This will cause the
markdown fields to be rendered and the generated HTML stored in a
`<field>_html` attribute on the record. We also store the version
used for generating the markdown.

All other classes that include this model will include the
`Gitlab::MarkdownCache::Redis::Extension`. This add the `<field>_html`
attributes to that model and will generate the html in them. The
generated HTML will be cached in redis under the key
`markdown_cache:<class>:<id>`. The class this included in must
therefore respond to `id`.

1 files changed, 1 insertions, 2 deletions

diff --git a/spec/features/markdown/gitlab_flavored_markdown_spec.rb b/spec/features/markdown/gitlab_flavored_markdown_spec.rb
index 6997ca48427..8fda3c7193e 100644
--- a/spec/features/markdown/gitlab_flavored_markdown_spec.rb
+++ b/spec/features/markdown/gitlab_flavored_markdown_spec.rb
@@ -20,8 +20,7 @@ describe "GitLab Flavored Markdown" do
     let(:commit) { project.commit }
 
     before do
-      allow_any_instance_of(Commit).to receive(:title)
-        .and_return("fix #{issue.to_reference}\n\nask #{fred.to_reference} for details")
+      create_commit("fix #{issue.to_reference}\n\nask #{fred.to_reference} for details", project, user, 'master')
     end
 
     it "renders title in commits#index" do