Update find-successful-workflow.ts

find-successful-workflow.ts

@@ -39,12 +39,23 @@ let BASE_SHA: string;
   });
   const HEAD_SHA = headResult.stdout;
 
-  if (['pull_request', 'pull_request_target'].includes(eventName) && !github.context.payload.pull_request.merged) {
-    const baseResult = spawnSync('git', ['merge-base', `origin/${mainBranchName}`, 'HEAD'], { encoding: 'utf-8' });
-    BASE_SHA = baseResult.stdout;
-  } else if (eventName == "merge_group") {
-    const baseResult = spawnSync('git', ['rev-parse', 'HEAD^1'], { encoding: 'utf-8' });
-    BASE_SHA = baseResult.stdout;
+  if (
+    (["pull_request", "pull_request_target"].includes(eventName) &&
+      !github.context.payload.pull_request.merged) ||
+    eventName == "merge_group"
+  ) {
+    try {
+      const mergeBaseRef = await findMergeBaseRef();
+      const baseResult = spawnSync(
+        "git",
+        ["merge-base", `origin/${mainBranchName}`, mergeBaseRef],
+        { encoding: "utf-8" }
+      );
+      BASE_SHA = baseResult.stdout;
+    } catch (e) {
+      core.setFailed(e.message);
+      return;
+    }
   } else {
     try {
       BASE_SHA = await findSuccessfulCommit(
@@ -175,6 +186,38 @@ async function findSuccessfulCommit(
   return await findExistingCommit(octokit, branch, shas);
 }
 
+async function findMergeBaseRef(): Promise<string> {
+  if (eventName == "merge_group") {
+    const mergeQueueBranch = await findMergeQueueBranch();
+    return `origin/${mergeQueueBranch}`;
+  } else {
+    return "HEAD";
+  }
+}
+
+function findMergeQueuePr(): string {
+  const { head_ref, base_sha } = github.context.payload.merge_group;
+  const result = new RegExp(
+    `^refs/heads/gh-readonly-queue/${mainBranchName}/pr-(\\d+)-${base_sha}$`
+  ).exec(head_ref);
+  return result ? result.at(1) : undefined;
+}
+
+async function findMergeQueueBranch(): Promise<string> {
+  const pull_number = findMergeQueuePr();
+  if (!pull_number) {
+    throw new Error("Failed to determine PR number");
+  }
+  process.stdout.write("\n");
+  process.stdout.write(`Found PR #${pull_number} from merge queue branch\n`);
+  const octokit = new ProxifiedClient();
+  const result = await octokit.request(
+    `GET /repos/${owner}/${repo}/pulls/${pull_number}`,
+    { owner, repo, pull_number: +pull_number }
+  );
+  return result.data.head.ref;
+}
+
 /**
  * Get first existing commit
  */