fix(gitlab): verify if MR is mergeable before setting automerge

[tmeijn]

This polls the Gitlab Merge requests API for the required status that's needed before setting merge_when_pipeline_succeeds to true.

Closes #6248

[viceice]

You need to mock delay in tests: jest.mock('delay', () => Promise.resolve());

[CLAassistant]

All committers have signed the CLA.

[tmeijn]

@viceice Sorry I have little to no experience with testing. I tried to do what you suggested, but it still seems to fail. Can you help me out?

[viceice]

ok, can you first fix your commits to use the right author

[viceice]

You need to add the following after describe('createPr(branchName, title, body)', () => {.

line ~956

    beforeEach(() => {
      api.get.mockResolvedValueOnce(
        partial<GotResponse>({
          body: {
            merge_status: 'can_be_merged',
            pipeline: {
              id: 29626725,
              sha: '2be7ddb704c7b6b83732fdd5b9f09d5a397b5f8f',
              ref: 'patch-28',
              status: 'success',
            },
          },
        })
      );
    });

[tmeijn]

@viceice @rarkins Any pointers on how to proceed? It fails on code coverage, saying the await delay statement is not covered. Again, no experience with testing.

[rarkins]

Why is this change necessary? It will slow down automerging for GitLab users unless it succeeds in setting the flag in the same run the MR is created in.

Edit: Sorry, now I see the linked issue. Seems it's workaround for a GitLab flaw. Do you expect that in most cases the flag will still be set in the first run, or in a later run? Have you verified that the logic will still work on a later run?

[tmeijn]

Do you expect that in most cases the flag will still be set in the first run, or in a later run? Have you verified that the logic will still work on a later run?

So I'm on Renovate 19.76.3 and of these MRs:

(Log of the relevant job can by found here: https://pastebin.com/YHaZXhW7)

all of them except protractor should've been Gitlab automerged by setting merge when pipeline succeeds. They were not however, they were merged by a second run of Renovate bot. You can see in the log they all returned 405 when trying to set the flag.

If you mean a later run of Renovate bot, I do not think Renovate as of 19.76.3 tries to set the merge when pipeline succeeds flag when a merge request is already created in a previous run.

Difficult thing is, I tried to reason about this as thorough as I could by going through the docs and issues in Gitlab, but I didn't hear anybody else here having this issue.

[renovate-release]

🎉 This PR is included in version 20.8.2 🎉

The release is available on:

• GitHub release
• 20.8.2

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