replace CLI flag with environment variable

Author: SRHerzog

lib/internal/test_runner/runner.js

@@ -145,7 +145,6 @@ function getRunArgs({ path, inspectPort }) {
     ArrayPrototypePush(argv, `--inspect-port=${getInspectPort(inspectPort)}`);
   }
   ArrayPrototypePush(argv, path);
-  ArrayPrototypeUnshift(argv, '--test-child-process');
 
   return argv;
 }
@@ -262,7 +261,7 @@ function runTestFile(path, root, inspectPort, filesWatcher) {
   const subtest = root.createSubtest(FileTest, path, async (t) => {
     const args = getRunArgs({ path, inspectPort });
     const stdio = ['pipe', 'pipe', 'pipe'];
-    const env = { ...process.env };
+    const env = { ...process.env, TEST_CONTEXT: 'child' };
     if (filesWatcher) {
       stdio.push('ipc');
       env.WATCH_REPORT_DEPENDENCIES = '1';

lib/internal/test_runner/utils.js

@@ -9,6 +9,7 @@ const {
   SafeMap,
   Symbol,
 } = primordials;
+
 const { basename } = require('path');
 const { createWriteStream } = require('fs');
 const { pathToFileURL } = require('internal/url');
@@ -174,7 +175,7 @@ function parseCommandLine() {
   const coverage = getOptionValue('--experimental-test-coverage');
   let destinations = getOptionValue('--test-reporter-destination');
   let reporters = getOptionValue('--test-reporter');
-  const isChildProcess = getOptionValue('--test-child-process');
+  const isChildProcess = process.env.TEST_CONTEXT === 'child';
   let testNamePatterns;
   let testOnlyFlag;
 

src/node_options.cc

@@ -596,9 +596,6 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "report given reporter to the given destination",
             &EnvironmentOptions::test_reporter_destination,
             kAllowedInEnvvar);
-  AddOption("--test-child-process",
-            "",  // for internal use by test runner
-            &EnvironmentOptions::test_child_process);
   AddOption("--test-only",
             "run tests with 'only' option set",
             &EnvironmentOptions::test_only,