test_runner: support custom arguments in run()

Author: avivkeller

doc/api/test.md

@@ -1299,6 +1299,12 @@ changes:
   * `setup` {Function} A function that accepts the `TestsStream` instance
     and can be used to setup listeners before any tests are run.
     **Default:** `undefined`.
+  * `execArgv` {Array} An array of CLI flags to pass to the `node` executable when
+    spawning the subprocesses. This option has no effect when `isolation` is `'none`'.
+    **Default:** `[]`
+  * `argv` {Array} An array of CLI flags to pass to each test file when spawning the
+    subprocesses. This option has no effect when `isolation` is `'none'`.
+    **Default:** `[]`.
   * `signal` {AbortSignal} Allows aborting an in-progress test execution.
   * `testNamePatterns` {string|RegExp|Array} A String, RegExp or a RegExp Array,
     that can be used to only run tests whose name matches the provided pattern.

lib/internal/test_runner/runner.js

@@ -130,7 +130,13 @@ function filterExecArgv(arg, i, arr) {
   !ArrayPrototypeSome(kFilterArgValues, (p) => arg === p || (i > 0 && arr[i - 1] === p) || StringPrototypeStartsWith(arg, `${p}=`));
 }
 
-function getRunArgs(path, { forceExit, inspectPort, testNamePatterns, testSkipPatterns, only }) {
+function getRunArgs(path, { forceExit,
+                            inspectPort,
+                            testNamePatterns,
+                            testSkipPatterns,
+                            only,
+                            argv: suppliedArgs,
+                            execArgv }) {
   const argv = ArrayPrototypeFilter(process.execArgv, filterExecArgv);
   if (forceExit === true) {
     ArrayPrototypePush(argv, '--test-force-exit');
@@ -148,12 +154,20 @@ function getRunArgs(path, { forceExit, inspectPort, testNamePatterns, testSkipPa
     ArrayPrototypePush(argv, '--test-only');
   }
 
+  for (let i = 0; i < execArgv.length; i++) {
+    ArrayPrototypePush(argv, execArgv[i]);
+  }
+
   if (path === kIsolatedProcessName) {
     ArrayPrototypePush(argv, '--test', ...ArrayPrototypeSlice(process.argv, 1));
   } else {
     ArrayPrototypePush(argv, path);
   }
 
+  for (let i = 0; i < suppliedArgs.length; i++) {
+    ArrayPrototypePush(argv, suppliedArgs[i]);
+  }
+
   return argv;
 }
 
@@ -548,6 +562,8 @@ function run(options = kEmptyObject) {
     lineCoverage = 0,
     branchCoverage = 0,
     functionCoverage = 0,
+    execArgv = [],
+    argv = [],
   } = options;
 
   if (files != null) {
@@ -643,6 +659,9 @@ function run(options = kEmptyObject) {
   validateInteger(branchCoverage, 'options.branchCoverage', 0, 100);
   validateInteger(functionCoverage, 'options.functionCoverage', 0, 100);
 
+  validateStringArray(argv, 'options.argv');
+  validateStringArray(execArgv, 'options.execArgv');
+
   const rootTestOptions = { __proto__: null, concurrency, timeout, signal };
   const globalOptions = {
     __proto__: null,
@@ -685,6 +704,8 @@ function run(options = kEmptyObject) {
     forceExit,
     cwd,
     isolation,
+    argv,
+    execArgv,
   };
 
   if (isolation === 'process') {

test/fixtures/test-runner/print-arguments.js

@@ -0,0 +1,5 @@
+const { test } = require('node:test');
+
+test('process.argv is setup', (t) => {
+    t.assert.deepStrictEqual(process.argv.slice(2), ['--a-custom-argument']);
+});

test/parallel/test-runner-run.mjs

@@ -33,6 +33,20 @@ describe('require(\'node:test\').run', { concurrency: true }, () => {
     for await (const _ of stream);
   });
 
+  const argPrintingFile = join(testFixtures, 'print-arguments.js');
+  it('should allow custom arguments via execArgv', async () => {
+    const result = await run({ files: [argPrintingFile], execArgv: ['-p', '"Printed"'] }).compose(spec).toArray();
+    assert.strictEqual(result[0].toString(), 'Printed\n');
+  });
+
+  it('should allow custom arguments via argv', async () => {
+    const stream = run({ files: [argPrintingFile], argv: ['--a-custom-argument'] });
+    stream.on('test:fail', common.mustNotCall());
+    stream.on('test:pass', common.mustCall(1));
+    // eslint-disable-next-line no-unused-vars
+    for await (const _ of stream);
+  });
+
   it('should run same file twice', async () => {
     const stream = run({
       files: [