test_runner: introduce NODE_TEST_WORKER_ID for improved concurrent test execution

Added a new environment variable, `NODE_TEST_WORKER_ID`, which ranges from 1 to N when `--experimental-test-isolation=process` is enabled and defaults to 1 when `--experimental-test-isolation=none` is used.

Author: 0hmX

doc/api/cli.md

@@ -2157,15 +2157,6 @@ are:
 * Running `pre` or `post` scripts in addition to the specified script.
 * Defining package manager-specific environment variables.
 
-#### Environment variables
-
-The following environment variables are set when running a script with `--run`:
-
-* `NODE_RUN_SCRIPT_NAME`: The name of the script being run. For example, if
-  `--run` is used to run `test`, the value of this variable will be `test`.
-* `NODE_RUN_PACKAGE_JSON_PATH`: The path to the `package.json` that is being
-  processed.
-
 ### `--secure-heap=n`
 
 <!-- YAML
@@ -3306,6 +3297,12 @@ If `value` equals `'child'`, test reporter options will be overridden and test
 output will be sent to stdout in the TAP format. If any other value is provided,
 Node.js makes no guarantees about the reporter format used or its stability.
 
+### `NODE_TEST_WORKER_ID`
+
+This environment variable is set by the test runner. When using process-level test
+isolation, each worker process is assigned a unique ID, starting at `1`. This is
+set to 1 for all tests when test isolation is disabled.
+
 ### `NODE_TLS_REJECT_UNAUTHORIZED=value`
 
 If `value` equals `'0'`, certificate validation is disabled for TLS connections.

lib/internal/test_runner/runner.js

@@ -358,14 +358,14 @@ class FileTest extends Test {
   }
 }
 
-function runTestFile(path, filesWatcher, opts) {
+function runTestFile(path, filesWatcher, opts, workerId = 1) {
   const watchMode = filesWatcher != null;
   const testPath = path === kIsolatedProcessName ? '' : path;
   const testOpts = { __proto__: null, signal: opts.signal };
   const subtest = opts.root.createSubtest(FileTest, testPath, testOpts, async (t) => {
     const args = getRunArgs(path, opts);
     const stdio = ['pipe', 'pipe', 'pipe'];
-    const env = { __proto__: null, ...process.env, NODE_TEST_CONTEXT: 'child-v8' };
+    const env = { __proto__: null, ...process.env, NODE_TEST_CONTEXT: 'child-v8', NODE_TEST_WORKER_ID: workerId };
     if (watchMode) {
       stdio.push('ipc');
       env.WATCH_REPORT_DEPENDENCIES = '1';
@@ -724,8 +724,10 @@ function run(options = kEmptyObject) {
     runFiles = () => {
       root.harness.bootstrapPromise = null;
       root.harness.buildPromise = null;
+      let workerId = 1;
       return SafePromiseAllSettledReturnVoid(testFiles, (path) => {
-        const subtest = runTestFile(path, filesWatcher, opts);
+        const subtest = runTestFile(path, filesWatcher, opts, workerId);
+        workerId++;
         filesWatcher?.runningSubtests.set(path, subtest);
         return subtest;
       });
@@ -766,6 +768,7 @@ function run(options = kEmptyObject) {
 
             root.entryFile = resolve(testFile);
             debug('loading test file:', fileURL.href);
+            process.env.NODE_TEST_WORKER_ID = 1;
             try {
               await cascadedLoader.import(fileURL, parent, { __proto__: null });
             } catch (err) {

test/fixtures/test-runner/worker-id/1.test.js

@@ -0,0 +1,5 @@
+const test = require('node:test');
+
+test('test1', t => {
+    console.log('NODE_TEST_WORKER_ID', process.env.NODE_TEST_WORKER_ID)
+});

test/fixtures/test-runner/worker-id/2.test.js

@@ -0,0 +1,5 @@
+const test = require('node:test');
+
+test('test2', t => {
+    console.log('NODE_TEST_WORKER_ID', process.env.NODE_TEST_WORKER_ID)
+});

test/fixtures/test-runner/worker-id/3.test.js

@@ -0,0 +1,5 @@
+const test = require('node:test');
+
+test('test3', t => {
+    console.log('NODE_TEST_WORKER_ID', process.env.NODE_TEST_WORKER_ID)
+});

test/parallel/test-runner-worker-id.js

@@ -0,0 +1,100 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const test = require('node:test');
+const { spawnSync, spawn } = require('child_process');
+const { join } = require('path');
+const fixtures = require('../common/fixtures');
+const testFixtures = fixtures.path('test-runner');
+
+test('testing with isolation enabled', () => {
+  const args = ['--test', '--experimental-test-isolation=process'];
+  const child = spawnSync(process.execPath, args, { cwd: join(testFixtures, 'worker-id') });
+
+  assert.strictEqual(child.stderr.toString(), '');
+  const stdout = child.stdout.toString();
+
+  assert.match(stdout, /NODE_TEST_WORKER_ID 1/);
+  assert.match(stdout, /NODE_TEST_WORKER_ID 2/);
+  assert.match(stdout, /NODE_TEST_WORKER_ID 3/);
+
+  assert.strictEqual(child.status, 0);
+});
+
+test('testing with isolation disabled', () => {
+  const args = ['--test', '--experimental-test-isolation=none'];
+  const child = spawnSync(process.execPath, args, { cwd: join(testFixtures, 'worker-id') });
+
+  assert.strictEqual(child.stderr.toString(), '');
+  const stdout = child.stdout.toString();
+  const regex = /NODE_TEST_WORKER_ID 1/g;
+  const result = stdout.match(regex);
+
+  assert.strictEqual(result.length, 3);
+  assert.strictEqual(child.status, 0);
+});
+
+
+test('testing with isolation enabled in watch mode', async () => {
+  const args = ['--watch', '--test', '--experimental-test-isolation=process'];
+
+  const child = spawn(process.execPath, args, { cwd: join(testFixtures, 'worker-id') });
+
+  let outputData = '';
+  let errorData = '';
+
+  child.stdout.on('data', (data) => {
+    outputData += data.toString();
+  });
+
+  child.stderr.on('data', (data) => {
+    errorData += data.toString();
+  });
+
+  setTimeout(() => {
+    child.kill();
+
+    assert.strictEqual(errorData, '');
+    assert.match(outputData, /NODE_TEST_WORKER_ID 1/);
+    assert.match(outputData, /NODE_TEST_WORKER_ID 2/);
+    assert.match(outputData, /NODE_TEST_WORKER_ID 3/);
+
+    if (child.exitCode !== null) {
+      assert.strictEqual(child.exitCode, null); // Since we killed it manually
+    }
+  }, 1000);
+
+});
+
+test('testing with isolation disabled in watch mode', async () => {
+  const args = ['--watch', '--test', '--experimental-test-isolation=none'];
+
+  const child = spawn(process.execPath, args, { cwd: join(testFixtures, 'worker-id') });
+
+  let outputData = '';
+  let errorData = '';
+
+  child.stdout.on('data', (data) => {
+    outputData += data.toString();
+  });
+
+  child.stderr.on('data', (data) => {
+    errorData += data.toString();
+  });
+
+  setTimeout(() => {
+    child.kill();
+
+    assert.strictEqual(errorData, '');
+    const regex = /NODE_TEST_WORKER_ID 1/g;
+    const result = outputData.match(regex);
+
+    assert.strictEqual(result.length, 3);
+
+    if (child.exitCode !== null) {
+      assert.strictEqual(child.exitCode, null);
+    }
+  }, 1000);
+
+});