fix(vitest): resolve the quarantine runner with the current build's extension

packages/vitest/src/reporter.ts

@@ -1,4 +1,4 @@
-import { dirname, resolve } from 'node:path';
+import { dirname, extname, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import type {
   FlakyDetectionContext,
@@ -157,10 +157,15 @@ export class MergifyReporter implements Reporter {
     // Provide quarantine list to workers via ProvidedContext
     vitest.provide('mergify:quarantine', [...this.quarantineList]);
 
-    // Auto-configure the custom runner if not already set
-    const dir =
-      typeof __dirname !== 'undefined' ? __dirname : dirname(fileURLToPath(import.meta.url));
-    const mergifyRunner = resolve(dir, 'runner.js');
+    // Auto-configure the custom runner if not already set.
+    // Resolve the runner sibling with the same extension as the current module: the build emits
+    // dist/index.cjs + dist/runner.cjs and dist/index.mjs + dist/runner.mjs (never runner.js), and
+    // in dev the sibling is src/runner.ts. A hardcoded 'runner.js' only worked in dev, where
+    // vite-node remaps the .js specifier onto runner.ts — in the published package the path goes
+    // through native node resolution and ERR_MODULE_NOT_FOUND aborts every test file (#169).
+    const moduleFile =
+      typeof __filename !== 'undefined' ? __filename : fileURLToPath(import.meta.url);
+    const mergifyRunner = resolve(dirname(moduleFile), `runner${extname(moduleFile)}`);
     if (!vitest.config.runner) {
       vitest.config.runner = mergifyRunner;
     } else if (vitest.config.runner !== mergifyRunner) {

packages/vitest/tests/dist-runner.test.ts

@@ -0,0 +1,33 @@
+import { resolve } from 'node:path';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { startVitest } from 'vitest/node';
+// Same scenario as runner.test.ts but consuming the BUILT package, the way a
+// real consumer does — this is the path #169 crashed on.
+// eslint-disable-next-line import/no-unresolved
+import { MergifyReporter } from '../dist/index.mjs';
+
+const fixturesDir = resolve(import.meta.dirname, 'fixtures');
+
+describe('Quarantine runner (dist build)', () => {
+  beforeEach(() => {
+    vi.stubEnv('GITHUB_ACTIONS', 'true');
+    vi.stubEnv('GITHUB_REPOSITORY', 'test-owner/test-repo');
+  });
+  afterEach(() => {
+    vi.unstubAllEnvs();
+  });
+
+  it('quarantined failing test does not fail the run', async () => {
+    const reporter = new MergifyReporter({
+      quarantineList: ['failing.test.ts > math > fails intentionally'],
+    });
+    const vitest = await startVitest('test', [], {
+      root: fixturesDir,
+      include: ['failing.test.ts'],
+      reporters: [reporter],
+      watch: false,
+    });
+    await vitest?.close();
+    expect(reporter.getSession()!.status).toBe('passed');
+  });
+});