test: verify Planner auto-merge guards against stale and unrelated changes

Author: zzylol

.github/workflows/mvp-ci.yml

@@ -51,7 +51,9 @@ jobs:
 
       - name: Test Planner dependency updater
         working-directory: ASAPQuery-backend
-        run: python3 -m unittest discover -s scripts/ci -p 'test_*.py'
+        run: |
+          python3 -m unittest discover -s scripts/ci -p 'test_*.py'
+          node scripts/ci/test_planner_merge.js
 
       - name: Check workspace formatting
         working-directory: ASAPQuery-backend

.github/workflows/planner-main-merge.yml

@@ -28,8 +28,10 @@ jobs:
             if (prs.data.length !== 1) return;
             const {data: pr} = await github.rest.pulls.get({owner, repo, pull_number: prs.data[0].number});
             if (pr.head.repo.full_name !== `${owner}/${repo}` || pr.head.sha !== run.head_sha || pr.draft) return;
-            const testedPr = run.pull_requests.find(p => p.number === pr.number);
-            if (!testedPr || testedPr.base.sha !== pr.base.sha) {
+            const {data: comparison} = await github.rest.repos.compareCommitsWithBasehead({
+              owner, repo, basehead: `main...${run.head_sha}`
+            });
+            if (comparison.merge_base_commit.sha !== comparison.base_commit.sha) {
               core.info('Main changed since this CI run; wait for the next updater refresh.');
               return;
             }

scripts/ci/README.md

@@ -24,6 +24,7 @@ then run the same checks as MVP CI. Updater unit tests run with:
 
 ```sh
 python3 -m unittest discover -s scripts/ci -p 'test_*.py'
+node scripts/ci/test_planner_merge.js
 ```
 
 The sync script and scheduled workflow are shared with PR #765, at the same paths

scripts/ci/test_planner_merge.js

@@ -0,0 +1,44 @@
+// Execute the privileged workflow handler with mocked GitHub responses.
+const fs = require('node:fs');
+const path = require('node:path');
+const workflow = fs.readFileSync(path.join(__dirname, '../../.github/workflows/planner-main-merge.yml'), 'utf8');
+const script = workflow.split('          script: |\n')[1].split('\n').map(line => line.slice(12)).join('\n');
+const AsyncFunction = Object.getPrototypeOf(async function () {}).constructor;
+const handler = new AsyncFunction('github', 'context', 'core', script);
+
+async function verifyMergeGuards() {
+  for (const scenario of ['valid', 'stale-head', 'foreign-repo', 'draft', 'stale-main', 'extra-file', 'empty-diff', 'no-pr']) {
+    let merged = false;
+    let failed = false;
+    const pr = {
+      number: 12,
+      head: {repo: {full_name: scenario === 'foreign-repo' ? 'else/repo' : 'o/r'}, sha: scenario === 'stale-head' ? 'old' : 'new'},
+      draft: scenario === 'draft',
+    };
+    const github = {
+      rest: {
+        pulls: {
+          list: async () => ({data: scenario === 'no-pr' ? [] : [pr]}),
+          get: async () => ({data: pr}),
+          listFiles: () => {},
+          merge: async args => {
+            if (args.sha !== 'new' || args.pull_number !== 12) throw Error('Wrong merge target');
+            merged = true;
+          },
+        },
+        repos: {compareCommitsWithBasehead: async () => ({data: {
+          merge_base_commit: {sha: scenario === 'stale-main' ? 'old' : 'base'},
+          base_commit: {sha: 'base'},
+        }})},
+      },
+      paginate: async () => scenario === 'empty-diff' ? [] : [{filename: scenario === 'extra-file' ? 'other.rs' : 'Cargo.toml'}],
+    };
+    await handler(github, {repo: {owner: 'o', repo: 'r'}, payload: {workflow_run: {head_sha: 'new'}}}, {
+      info: () => {}, setFailed: () => { failed = true; },
+    });
+    if (merged !== (scenario === 'valid')) throw Error(`Unexpected merge: ${scenario}`);
+    if (failed !== ['extra-file', 'empty-diff'].includes(scenario)) throw Error(`Unexpected failure: ${scenario}`);
+  }
+}
+
+verifyMergeGuards().catch(error => { console.error(error); process.exitCode = 1; });