Optimize merge request refresh by using the database to check commit SHAssh-optimize-mr-commit-sha-lookup

Previously for a given merge request, we would:

1. Create the array of commit SHAs involved in the push (A)
2. Request all merge request commits and map the SHA (B)
3. Reload the diff if there were any common commits between A and B

We can avoid additional database querying and overhead by
checking with the database whether the merge request contains any
of the commit SHAs.

Relates to https://gitlab.com/gitlab-org/gitlab-ce/issues/53213

1 files changed, 26 insertions, 0 deletions

diff --git a/spec/models/merge_request_spec.rb b/spec/models/merge_request_spec.rb
index 7d500f9e579..2eb5e39ccfd 100644
--- a/spec/models/merge_request_spec.rb
+++ b/spec/models/merge_request_spec.rb
@@ -2611,6 +2611,32 @@ describe MergeRequest do
     end
   end
 
+  describe '#includes_any_commits?' do
+    it 'returns false' do
+      expect(subject.includes_any_commits?([Gitlab::Git::BLANK_SHA])).to be_falsey
+    end
+
+    it 'returns true' do
+      expect(subject.includes_any_commits?([subject.merge_request_diff.head_commit_sha])).to be_truthy
+    end
+
+    it 'returns true even when there is a non-existent comit' do
+      expect(subject.includes_any_commits?([Gitlab::Git::BLANK_SHA, subject.merge_request_diff.head_commit_sha])).to be_truthy
+    end
+
+    context 'unpersisted merge request' do
+      let(:new_mr) { build(:merge_request) }
+
+      it 'returns false' do
+        expect(new_mr.includes_any_commits?([Gitlab::Git::BLANK_SHA])).to be_falsey
+      end
+
+      it 'returns true' do
+        expect(new_mr.includes_any_commits?([subject.merge_request_diff.head_commit_sha])).to be_truthy
+      end
+    end
+  end
+
   describe '#can_allow_collaboration?' do
     let(:target_project) { create(:project, :public) }
     let(:source_project) { fork_project(target_project) }