test_runner: address review feedback

- Remove processExecArgv option: process.execArgv is runtime state
  that should not be a public API option. Keep reading it directly
  in getRunArgs() as before.
- Fix env with isolation=none: only set options.env from CLI entry
  point when isolation is not 'none', preventing ERR_INVALID_ARG_VALUE
  when using --test-isolation=none.
- Add documentation for the env option in doc/api/test.md.
- Add tests for env option acceptance and env+isolation=none rejection.

Author: murataslan1

doc/api/test.md

@@ -1546,6 +1546,9 @@ changes:
   * `setup` {Function} A function that accepts the `TestsStream` instance
     and can be used to setup listeners before any tests are run.
     **Default:** `undefined`.
+  * `env` {Object} Environment variables to pass to test child processes.
+    This option has no effect when `isolation` is `'none'`.
+    **Default:** `process.env`.
   * `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:** `[]`

lib/internal/main/test_runner.js

@@ -33,8 +33,9 @@ if (isUsingInspector() && options.isolation === 'process') {
 // Capture process state explicitly so run() does not need to access it.
 options.globPatterns = ArrayPrototypeSlice(process.argv, 1);
 options.cwd = process.cwd();
-options.env = process.env;
-options.processExecArgv = process.execArgv;
+if (options.isolation !== 'none') {
+  options.env = process.env;
+}
 
 debug('test runner configuration:', options);
 run(options).on('test:summary', (data) => {

lib/internal/test_runner/runner.js

@@ -167,7 +167,6 @@ function getRunArgs(path, { forceExit,
                             only,
                             argv: suppliedArgs,
                             execArgv,
-                            processExecArgv,
                             globPatterns,
                             rerunFailuresFilePath,
                             root: { timeout },
@@ -185,7 +184,7 @@ function getRunArgs(path, { forceExit,
    */
   const nodeOptionsSet = new SafeSet(processNodeOptions);
   const unknownProcessExecArgv = ArrayPrototypeFilter(
-    processExecArgv,
+    process.execArgv,
     (arg) => !nodeOptionsSet.has(arg),
   );
   ArrayPrototypePushApply(runArgs, unknownProcessExecArgv);
@@ -653,7 +652,6 @@ function run(options = kEmptyObject) {
     execArgv = [],
     argv = [],
     cwd,
-    processExecArgv,
     rerunFailuresFilePath,
     env,
   } = options;
@@ -668,9 +666,6 @@ function run(options = kEmptyObject) {
   if (env === undefined) {
     env = process.env;
   }
-  if (processExecArgv === undefined) {
-    processExecArgv = process.execArgv;
-  }
 
   if (files != null) {
     validateArray(files, 'options.files');
@@ -849,7 +844,6 @@ function run(options = kEmptyObject) {
     isolation,
     argv,
     execArgv,
-    processExecArgv,
     rerunFailuresFilePath,
     env,
     workerIdPool: isolation === 'process' ? workerIdPool : null,

test/parallel/test-runner-run.mjs

@@ -687,6 +687,27 @@ describe('forceExit', () => {
       message: /The property 'options\.forceExit' is not supported with watch mode\./
     });
   });
+
+  it('should accept env option and pass it to child processes', async () => {
+    const stream = run({
+      files: [join(testFixtures, 'default-behavior/test/random.cjs')],
+      env: { ...process.env, NODE_TEST_CUSTOM_ENV_VAR: '1' },
+    });
+    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 reject env option with isolation none', () => {
+    assert.throws(() => run({
+      files: [join(testFixtures, 'default-behavior/test/random.cjs')],
+      isolation: 'none',
+      env: { FOO: 'bar' },
+    }), {
+      code: 'ERR_INVALID_ARG_VALUE',
+    });
+  });
 });