Scope tests against DeprecatedHighlightCache

spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb

@@ -29,6 +29,11 @@ describe Gitlab::Diff::FileCollection::MergeRequestDiff do
     let(:diffable) { merge_request.merge_request_diff }
   end
 
+  context 'using Gitlab::Diff::DeprecatedHighlightCache' do
+    before do
+      stub_feature_flags(redis_diff_caching: false)
+    end
+
     it 'uses a different cache key if diff line keys change' do
       mr_diff = described_class.new(merge_request.merge_request_diff, diff_options: nil)
       key = mr_diff.cache_key
@@ -37,6 +42,7 @@ describe Gitlab::Diff::FileCollection::MergeRequestDiff do
 
       expect(mr_diff.cache_key).not_to eq(key)
     end
+  end
 
   it_behaves_like 'diff statistics' do
     let(:collection_default_args) do

spec/services/merge_requests/reload_diffs_service_spec.rb

@@ -33,6 +33,11 @@ describe MergeRequests::ReloadDiffsService, :use_clean_rails_memory_store_cachin
     end
 
     context 'cache clearing' do
+      context 'using Gitlab::Diff::DeprecatedHighlightCache' do
+        before do
+          stub_feature_flags(redis_diff_caching: false)
+        end
+
         it 'clears the cache for older diffs on the merge request' do
           old_diff = merge_request.merge_request_diff
           old_cache_key = old_diff.diffs_collection.cache_key
@@ -41,6 +46,22 @@ describe MergeRequests::ReloadDiffsService, :use_clean_rails_memory_store_cachin
 
           subject.execute
         end
+      end
+
+      context 'using Gitlab::Diff::HighlightCache' do
+        before do
+          stub_feature_flags(redis_diff_caching: true)
+        end
+
+        it 'clears the cache for older diffs on the merge request' do
+          old_diff = merge_request.merge_request_diff
+          old_cache_key = old_diff.diffs_collection.cache_key
+
+          expect_any_instance_of(Redis).to receive(:del).with(old_cache_key).and_call_original
+
+          subject.execute
+        end
+      end
 
       it 'avoids N+1 queries', :request_store do
         current_user

spec/services/notes/create_service_spec.rb

@@ -87,11 +87,29 @@ describe Notes::CreateService do
           .to receive(:unfolded_diff?) { true }
       end
 
+      context 'using Gitlab::Diff::DeprecatedHighlightCache' do
+        before do
+          stub_feature_flags(redis_diff_caching: false)
+        end
+
         it 'clears noteable diff cache when it was unfolded for the note position' do
           expect_any_instance_of(Gitlab::Diff::DeprecatedHighlightCache).to receive(:clear)
 
           described_class.new(project_with_repo, user, new_opts).execute
         end
+      end
+
+      context 'using Gitlab::Diff::HighlightCache' do
+        before do
+          stub_feature_flags(redis_diff_caching: true)
+        end
+
+        it 'clears noteable diff cache when it was unfolded for the note position' do
+          expect_any_instance_of(Gitlab::Diff::HighlightCache).to receive(:clear)
+
+          described_class.new(project_with_repo, user, new_opts).execute
+        end
+      end
 
       it 'does not clear cache when note is not the first of the discussion' do
         prev_note =