Detect merge queue branch and retrieve real branch name from pull request

node-src/git/getBranchFromMergeQueuePullRequestNumber.ts

@@ -0,0 +1,30 @@
+import gql from 'fake-tag';
+import { Context } from '../types';
+
+const MergeQueueOriginalBranchQuery = gql`
+  query MergeQueueOriginalBranchQuery($number: Int!) {
+    app {
+      pullRequest(number: $number) {
+        branch: headRefName
+      }
+    }
+  }
+`
+interface MergeQueueOriginalBranchQueryResult {
+  app: {
+    pullRequest: {
+      branch: string;
+    };
+  };
+}
+
+export async function getBranchFromMergeQueuePullRequestNumber(
+  ctx: Pick<Context, 'options' | 'client' | 'git'>,
+  { number }: { number: number }
+) {
+  const { app } = await ctx.client.runQuery<MergeQueueOriginalBranchQueryResult>(MergeQueueOriginalBranchQuery, {
+    number
+  });
+
+  return app?.pullRequest?.branch;
+}

node-src/git/getCommitAndBranch.test.ts

@@ -2,15 +2,18 @@ import envCi from 'env-ci';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
 import * as git from './git';
-
+import * as mergeQueue from './getBranchFromMergeQueuePullRequestNumber';
 import getCommitAndBranch from './getCommitAndBranch';
 
 vi.mock('env-ci');
 vi.mock('./git');
+vi.mock('./getBranchFromMergeQueuePullRequestNumber');
 
 const getBranch = vi.mocked(git.getBranch);
 const getCommit = vi.mocked(git.getCommit);
 const hasPreviousCommit = vi.mocked(git.hasPreviousCommit);
+const getBranchFromMergeQueue = vi.mocked(mergeQueue.getBranchFromMergeQueuePullRequestNumber);
+const mergeQueueBranchMatch = vi.mocked(git.mergeQueueBranchMatch );
 
 const log = { info: vi.fn(), warn: vi.fn(), debug: vi.fn() };
 
@@ -26,12 +29,14 @@ beforeEach(() => {
     committerEmail: 'noreply@github.com',
   });
   hasPreviousCommit.mockResolvedValue(true);
+  mergeQueueBranchMatch.mockResolvedValue(null);
 });
 
 afterEach(() => {
   envCi.mockReset();
   getBranch.mockReset();
   getCommit.mockReset();
+  getBranchFromMergeQueue.mockReset();
 });
 
 const commitInfo = {
@@ -228,4 +233,15 @@ describe('getCommitAndBranch', () => {
       );
     });
   });
+
+  describe('with mergeQueue branch', () => {
+    it('uses PRs branchName as branch instead of temporary mergeQueue branch', async () => {
+      mergeQueueBranchMatch.mockResolvedValue(4);
+      getBranchFromMergeQueue.mockResolvedValue('branch-before-merge-queue');
+      const info = await getCommitAndBranch({ log }, {
+        branchName: 'this-is-merge-queue-branch-format/main/pr-4-48e0c83fadbf504c191bc868040b7a969a4f1feb',
+      });
+      expect(info).toMatchObject({ branch: 'branch-before-merge-queue' });
+    });
+  });
 });

node-src/git/getCommitAndBranch.ts

@@ -7,7 +7,9 @@ import missingTravisInfo from '../ui/messages/errors/missingTravisInfo';
 import customGitHubAction from '../ui/messages/info/customGitHubAction';
 import travisInternalBuild from '../ui/messages/warnings/travisInternalBuild';
 import noCommitDetails from '../ui/messages/warnings/noCommitDetails';
-import { getBranch, getCommit, hasPreviousCommit } from './git';
+import { getBranch, getCommit, hasPreviousCommit, mergeQueueBranchMatch } from './git';
+
+import { getBranchFromMergeQueuePullRequestNumber } from './getBranchFromMergeQueuePullRequestNumber';
 
 const ORIGIN_PREFIX_REGEXP = /^origin\//;
 const notHead = (branch) => (branch && branch !== 'HEAD' ? branch : false);
@@ -21,13 +23,14 @@ interface CommitInfo {
 }
 
 export default async function getCommitAndBranch(
-  { log },
+  ctx,
   {
     branchName,
     patchBaseRef,
     ci,
   }: { branchName?: string; patchBaseRef?: string; ci?: boolean } = {}
 ) {
+  const { log } = ctx;
   let commit: CommitInfo = await getCommit();
   let branch = notHead(branchName) || notHead(patchBaseRef) || (await getBranch());
   let slug;
@@ -157,6 +160,22 @@ export default async function getCommitAndBranch(
     branch = branch.replace(ORIGIN_PREFIX_REGEXP, '');
   }
 
+
+
+  // When a PR is put into a merge queue, and prior PR is merged, the PR is retested against the latest on main. 
+  // To do this, GitHub creates a new commit and does a CI run with the branch changed to e.g. gh-readonly-queue/main/pr-4-da07417adc889156224d03a7466ac712c647cd36
+  // If you configure merge queues to rebase in this circumstance, 
+  // we lose track of baselines as the branch name has changed so our usual rebase detection (based on branch name) doesn't work.
+  const mergeQueueBranchPrNumber = await mergeQueueBranchMatch(commit.commit, branch)
+  if (mergeQueueBranchPrNumber) {
+    // This is why we extract the PR number from the branch name and use it to find the branch name of the PR that was merged.
+    const branchFromMergeQueuePullRequestNumber = await getBranchFromMergeQueuePullRequestNumber(ctx, { number: mergeQueueBranchPrNumber });
+
+    if (branchFromMergeQueuePullRequestNumber) {
+      branch = branchFromMergeQueuePullRequestNumber;
+    }
+  }
+
   log.debug(
     `git info: ${JSON.stringify({
       commit,

node-src/git/git.test.ts

@@ -1,7 +1,7 @@
 import { execaCommand } from 'execa';
 import { describe, expect, it, vi } from 'vitest';
 
-import { getCommit, getSlug, hasPreviousCommit } from './git';
+import { getCommit, getSlug, hasPreviousCommit, mergeQueueBranchMatch } from './git';
 
 vi.mock('execa');
 
@@ -91,3 +91,20 @@ gpg: Can't check signature: No public key
     expect(await hasPreviousCommit()).toEqual(true);
   });
 });
+
+
+describe('mergeQueueBranchMatch', () => {
+  it('returns pr number if it is a merge queue branch', async () => {
+    const branch = "gh-readonly-queue/main/pr-4-da07417adc889156224d03a7466ac712c647cd36"
+    const commit = "da07417adc889156224d03a7466ac712c647cd36"
+    expect(await mergeQueueBranchMatch(commit, branch)).toEqual(4);
+  });
+
+  it('returns null if it is not a merge queue branch', async () => {
+    const branch = "develop"
+    const commit = "da07417adc889156224d03a7466ac712c647cd36"
+    expect(await mergeQueueBranchMatch(commit, branch)).toEqual(
+      null
+    );
+  });
+});

node-src/git/git.ts

@@ -281,3 +281,10 @@ export async function findFiles(...patterns: string[]) {
   const files = await execGitCommand(`git ls-files -z ${patterns.map((p) => `'${p}'`).join(' ')}`);
   return files.split('\0').filter(Boolean);
 }
+
+export async function mergeQueueBranchMatch(commit, branch) {
+  const mergeQueuePattern = new RegExp(`gh-readonly-queue/.*/pr-(\\d+)-${commit}$`);
+  const match = branch.match(mergeQueuePattern);
+
+  return match ? Number(match[1]) : null;
+}

node-src/index.test.ts

@@ -293,6 +293,7 @@ vi.mock('./git/git', () => ({
   getRepositoryRoot: () => Promise.resolve(process.cwd()),
   getUncommittedHash: () => Promise.resolve('abc123'),
   getUserEmail: () => Promise.resolve('test@test.com'),
+  mergeQueueBranchMatch: () => Promise.resolve(null),
 }));
 
 vi.mock('./git/getParentCommits', () => ({