test_runner,test: fix flaky test-runner-cli-concurrency.js

This test was flaky on Windows when trying to clean up the
tmp directory, probably because it relied on child processes
timing out and being killed.

This commit updates the test to check for debug output
from the test runner. This should be adequate because the
original change was effectively:

let concurrency = getOptionValue('--test-concurrency') || true;

The test runner now logs the value of the concurrency variable.

Fixes: #50101
PR-URL: #50108
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>

lib/internal/main/test_runner.js

@@ -18,6 +18,9 @@ const {
   RegExpPrototypeExec,
   StringPrototypeSplit,
 } = primordials;
+let debug = require('internal/util/debuglog').debuglog('test_runner', (fn) => {
+  debug = fn;
+});
 
 prepareMainThreadExecution(false);
 markBootstrapComplete();
@@ -57,8 +60,15 @@ if (shardOption) {
   };
 }
 
-run({ concurrency, inspectPort, watch: getOptionValue('--watch'), setup: setupTestReporters, shard })
-.on('test:fail', (data) => {
+const options = {
+  concurrency,
+  inspectPort,
+  watch: getOptionValue('--watch'),
+  setup: setupTestReporters,
+  shard,
+};
+debug('test runner configuration:', options);
+run(options).on('test:fail', (data) => {
   if (data.todo === undefined || data.todo === false) {
     process.exitCode = kGenericUserError;
   }

test/parallel/test-runner-cli-concurrency.js

@@ -1,45 +1,26 @@
 'use strict';
-const common = require('../common');
-const tmpdir = require('../common/tmpdir');
-const { deepStrictEqual, strictEqual } = require('node:assert');
+require('../common');
+const fixtures = require('../common/fixtures');
+const assert = require('node:assert');
 const { spawnSync } = require('node:child_process');
-const { readdirSync, writeFileSync } = require('node:fs');
-const { join } = require('node:path');
-const { beforeEach, test } = require('node:test');
+const { test } = require('node:test');
+const cwd = fixtures.path('test-runner', 'default-behavior');
+const env = { ...process.env, 'NODE_DEBUG': 'test_runner' };
 
-function createTestFile(name) {
-  writeFileSync(join(tmpdir.path, name), `
-    const fs = require('node:fs');
-
-    fs.unlinkSync(__filename);
-    setTimeout(() => {}, 1_000_000_000);
-  `);
-}
-
-beforeEach(() => {
-  tmpdir.refresh();
-  createTestFile('test-1.js');
-  createTestFile('test-2.js');
+test('default concurrency', async () => {
+  const args = ['--test'];
+  const cp = spawnSync(process.execPath, args, { cwd, env });
+  assert.match(cp.stderr.toString(), /concurrency: true,/);
 });
 
-test('concurrency of one', () => {
-  const cp = spawnSync(process.execPath, ['--test', '--test-concurrency=1'], {
-    cwd: tmpdir.path,
-    timeout: common.platformTimeout(1000),
-  });
-
-  strictEqual(cp.stderr.toString(), '');
-  strictEqual(cp.error.code, 'ETIMEDOUT');
-  deepStrictEqual(readdirSync(tmpdir.path), ['test-2.js']);
+test('concurrency of one', async () => {
+  const args = ['--test', '--test-concurrency=1'];
+  const cp = spawnSync(process.execPath, args, { cwd, env });
+  assert.match(cp.stderr.toString(), /concurrency: 1,/);
 });
 
-test('concurrency of two', () => {
-  const cp = spawnSync(process.execPath, ['--test', '--test-concurrency=2'], {
-    cwd: tmpdir.path,
-    timeout: common.platformTimeout(1000),
-  });
-
-  strictEqual(cp.stderr.toString(), '');
-  strictEqual(cp.error.code, 'ETIMEDOUT');
-  deepStrictEqual(readdirSync(tmpdir.path), []);
+test('concurrency of two', async () => {
+  const args = ['--test', '--test-concurrency=2'];
+  const cp = spawnSync(process.execPath, args, { cwd, env });
+  assert.match(cp.stderr.toString(), /concurrency: 2,/);
 });