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`.

3 files changed, 34 insertions, 12 deletions

diff --git a/spec/lib/banzai/commit_renderer_spec.rb b/spec/lib/banzai/commit_renderer_spec.rb
index 1f53657c59c..316dbf052c3 100644
--- a/spec/lib/banzai/commit_renderer_spec.rb
+++ b/spec/lib/banzai/commit_renderer_spec.rb
@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Banzai::CommitRenderer do
-  describe '.render' do
+  describe '.render', :clean_gitlab_redis_cache do
     it 'renders a commit description and title' do
       user = build(:user)
       project = create(:project, :repository)
@@ -13,7 +13,7 @@ describe Banzai::CommitRenderer do
 
       described_class::ATTRIBUTES.each do |attr|
         expect_any_instance_of(Banzai::ObjectRenderer).to receive(:render).with([project.commit], attr).once.and_call_original
-        expect(Banzai::Renderer).to receive(:cacheless_render_field).with(project.commit, attr, {})
+        expect(Banzai::Renderer).to receive(:cacheless_render_field).with(project.commit, attr, { skip_project_check: false }).and_call_original
       end
 
       described_class.render([project.commit], project, user)
diff --git a/spec/lib/banzai/object_renderer_spec.rb b/spec/lib/banzai/object_renderer_spec.rb
index 3b52f6666d0..7b855251a74 100644
--- a/spec/lib/banzai/object_renderer_spec.rb
+++ b/spec/lib/banzai/object_renderer_spec.rb
@@ -11,7 +11,7 @@ describe Banzai::ObjectRenderer do
     )
   end
 
-  let(:object) { Note.new(note: 'hello', note_html: '<p dir="auto">hello</p>', cached_markdown_version: CacheMarkdownField::CACHE_COMMONMARK_VERSION << 16) }
+  let(:object) { Note.new(note: 'hello', note_html: '<p dir="auto">hello</p>', cached_markdown_version: Gitlab::MarkdownCache::CACHE_COMMONMARK_VERSION << 16) }
 
   describe '#render' do
     context 'with cache' do
@@ -60,24 +60,38 @@ describe Banzai::ObjectRenderer do
     end
 
     context 'without cache' do
-      let(:commit) { project.commit }
+      let(:cacheless_class) do
+        Class.new do
+          attr_accessor :title, :redacted_title_html, :project
+
+          def banzai_render_context(field)
+            { project: project, pipeline: :single_line }
+          end
+        end
+      end
+      let(:cacheless_thing) do
+        cacheless_class.new.tap do |thing|
+          thing.title = "Merge branch 'branch-merged' into 'master'"
+          thing.project = project
+        end
+      end
 
       it 'renders and redacts an Array of objects' do
-        renderer.render([commit], :title)
+        renderer.render([cacheless_thing], :title)
 
-        expect(commit.redacted_title_html).to eq("Merge branch 'branch-merged' into 'master'")
+        expect(cacheless_thing.redacted_title_html).to eq("Merge branch 'branch-merged' into 'master'")
       end
 
       it 'calls Banzai::Redactor to perform redaction' do
         expect_any_instance_of(Banzai::Redactor).to receive(:redact).and_call_original
 
-        renderer.render([commit], :title)
+        renderer.render([cacheless_thing], :title)
       end
 
       it 'retrieves field content using Banzai::Renderer.cacheless_render_field' do
-        expect(Banzai::Renderer).to receive(:cacheless_render_field).with(commit, :title, {}).and_call_original
+        expect(Banzai::Renderer).to receive(:cacheless_render_field).with(cacheless_thing, :title, {}).and_call_original
 
-        renderer.render([commit], :title)
+        renderer.render([cacheless_thing], :title)
       end
     end
   end
diff --git a/spec/lib/banzai/renderer_spec.rb b/spec/lib/banzai/renderer_spec.rb
index 650cecfc778..aa828e2f0e9 100644
--- a/spec/lib/banzai/renderer_spec.rb
+++ b/spec/lib/banzai/renderer_spec.rb
@@ -11,16 +11,24 @@ describe Banzai::Renderer do
     object
   end
 
+  def fake_cacheless_object
+    object = double('cacheless object')
+
+    allow(object).to receive(:respond_to?).with(:cached_markdown_fields).and_return(false)
+
+    object
+  end
+
   describe '#render_field' do
     let(:renderer) { described_class }
 
     context 'without cache' do
-      let(:commit) { create(:project, :repository).commit }
+      let(:commit) { fake_cacheless_object }
 
       it 'returns cacheless render field' do
-        expect(renderer).to receive(:cacheless_render_field).with(commit, :title, {})
+        expect(renderer).to receive(:cacheless_render_field).with(commit, :field, {})
 
-        renderer.render_field(commit, :title)
+        renderer.render_field(commit, :field)
       end
     end