From 4bf9c844198e88575b03d7013934331d19a4d11d Mon Sep 17 00:00:00 2001
From: Marco Ippolito <marcoippolito54@gmail.com>
Date: Sat, 31 Jan 2026 15:50:29 +0100
Subject: [PATCH] src: allow empty --experimental-config-file

---
 doc/api/cli.md                                |  13 +-
 doc/api/test.md                               |   2 +-
 doc/node.1                                    |  11 +-
 lib/internal/main/watch_mode.js               |   8 +-
 lib/internal/process/pre_execution.js         |   3 +-
 lib/internal/test_runner/runner.js            |   6 +-
 src/node.cc                                   |  14 +-
 src/node_config_file.cc                       |  64 +++--
 src/node_config_file.h                        |   4 +-
 src/node_options.cc                           |   9 +-
 src/node_options.h                            |   1 -
 test/parallel/test-cli-node-options-docs.js   |   1 +
 test/parallel/test-cli-options-as-flags.js    |   6 +-
 test/parallel/test-config-file.js             | 240 +++++++++++-------
 test/parallel/test-permission-config-file.mjs |  27 +-
 test/parallel/test-runner-cli.js              |  43 ++--
 test/parallel/test-runner-flag-propagation.js |  15 +-
 test/sequential/test-watch-mode.mjs           |   4 +-
 18 files changed, 287 insertions(+), 184 deletions(-)

diff --git a/doc/api/cli.md b/doc/api/cli.md
index b0fd0bfb567299..74b02d5299b1a9 100644
--- a/doc/api/cli.md
+++ b/doc/api/cli.md
@@ -1045,7 +1045,7 @@ added:
 
 Enable experimental import support for `.node` addons.
 
-### `--experimental-config-file=config`
+### `--experimental-config-file=path`, `--experimental-config-file`
 
 <!-- YAML
 added:
@@ -1056,6 +1056,12 @@ added:
 > Stability: 1.0 - Early development
 
 If present, Node.js will look for a configuration file at the specified path.
+If the path is not specified, Node.js will look for a `node.config.json` file
+in the current working directory.
+To specify a custom path, use the `--experimental-config-file=path` form.
+The space-separated `--experimental-config-file path` form is not supported.
+The alias `--experimental-default-config-file` is equivalent to
+`--experimental-config-file` without an argument.
 Node.js will read the configuration file and apply the settings. The
 configuration file should be a JSON file with the following structure. `vX.Y.Z`
 in the `$schema` must be replaced with the version of Node.js you are using.
@@ -1162,9 +1168,10 @@ added:
 
 > Stability: 1.0 - Early development
 
-If the `--experimental-default-config-file` flag is present, Node.js will look for a
+This flag is an alias for `--experimental-config-file` without an argument.
+If present, Node.js will look for a
 `node.config.json` file in the current working directory and load it as a
-as configuration file.
+configuration file.
 
 ### `--experimental-eventsource`
 
diff --git a/doc/api/test.md b/doc/api/test.md
index e0e544ababec87..9cd06d7c2e23f9 100644
--- a/doc/api/test.md
+++ b/doc/api/test.md
@@ -4531,7 +4531,7 @@ test.describe('my suite', (suite) => {
 [`suite()`]: #suitename-options-fn
 [`test()`]: #testname-options-fn
 [code coverage]: #collecting-code-coverage
-[configuration files]: cli.md#--experimental-config-fileconfig
+[configuration files]: cli.md#--experimental-config-filepath---experimental-config-file
 [describe options]: #describename-options-fn
 [it options]: #testname-options-fn
 [module customization hooks]: module.md#customization-hooks
diff --git a/doc/node.1 b/doc/node.1
index 78a4a3f96fa285..2b1ee8d5f31679 100644
--- a/doc/node.1
+++ b/doc/node.1
@@ -623,8 +623,12 @@ It is possible to run code containing inline types unless the
 .It Fl -experimental-addon-modules
 Enable experimental import support for \fB.node\fR addons.
 .
-.It Fl -experimental-config-file Ns = Ns Ar config
+.It Fl -experimental-config-file= Ns Ar config , Fl -experimental-config-file , Fl -experimental-default-config-file
 If present, Node.js will look for a configuration file at the specified path.
+If the path is not specified, Node.js will look for a \fBnode.config.json\fR file
+in the current working directory.
+To specify a custom path, use the \fB--experimental-config-file=\fR\fBpath\fR form.
+The space-separated \fB--experimental-config-file path\fR form is not supported.
 Node.js will read the configuration file and apply the settings. The
 configuration file should be a JSON file with the following structure. \fBvX.Y.Z\fR
 in the \fB$schema\fR must be replaced with the version of Node.js you are using.
@@ -710,9 +714,10 @@ Node.js will not sanitize or perform validation on the user-provided configurati
 so \fBNEVER\fR use untrusted configuration files.
 .
 .It Fl -experimental-default-config-file
-If the \fB--experimental-default-config-file\fR flag is present, Node.js will look for a
+This flag is an alias for \fB--experimental-config-file\fR without an argument.
+If present, Node.js will look for a
 \fBnode.config.json\fR file in the current working directory and load it as a
-as configuration file.
+configuration file.
 .
 .It Fl -experimental-eventsource
 Enable exposition of EventSource Web API on the global scope.
diff --git a/lib/internal/main/watch_mode.js b/lib/internal/main/watch_mode.js
index 5e2e97f2fd60f2..63d1b51c815155 100644
--- a/lib/internal/main/watch_mode.js
+++ b/lib/internal/main/watch_mode.js
@@ -1,7 +1,6 @@
 'use strict';
 const {
   ArrayPrototypeForEach,
-  ArrayPrototypeIncludes,
   ArrayPrototypeJoin,
   ArrayPrototypeMap,
   ArrayPrototypePush,
@@ -67,11 +66,8 @@ for (let i = 0; i < process.execArgv.length; i++) {
     }
     continue;
   }
-  if (StringPrototypeStartsWith(arg, '--experimental-config-file')) {
-    if (!ArrayPrototypeIncludes(arg, '=')) {
-      // Skip the flag and the next argument (the config file path)
-      i++;
-    }
+  if (arg === '--experimental-config-file' ||
+      StringPrototypeStartsWith(arg, '--experimental-config-file=')) {
     continue;
   }
   if (arg === '--experimental-default-config-file') {
diff --git a/lib/internal/process/pre_execution.js b/lib/internal/process/pre_execution.js
index e822bbd4e92cdc..16a80c2d4f410f 100644
--- a/lib/internal/process/pre_execution.js
+++ b/lib/internal/process/pre_execution.js
@@ -397,8 +397,7 @@ function setupSQLite() {
 }
 
 function initializeConfigFileSupport() {
-  if (getOptionValue('--experimental-default-config-file') ||
-      getOptionValue('--experimental-config-file')) {
+  if (getOptionValue('--experimental-config-file')) {
     emitExperimentalWarning('--experimental-config-file');
   }
 }
diff --git a/lib/internal/test_runner/runner.js b/lib/internal/test_runner/runner.js
index bb3a8868309a94..2033ac16e8ea49 100644
--- a/lib/internal/test_runner/runner.js
+++ b/lib/internal/test_runner/runner.js
@@ -161,7 +161,11 @@ function createTestFileList(patterns, cwd) {
 
 function filterExecArgv(arg, i, arr) {
   return !ArrayPrototypeIncludes(kFilterArgs, arg) &&
-  !ArrayPrototypeSome(kFilterArgValues, (p) => arg === p || (i > 0 && arr[i - 1] === p) || StringPrototypeStartsWith(arg, `${p}=`));
+  !ArrayPrototypeSome(kFilterArgValues, (p) => {
+    return arg === p ||
+      StringPrototypeStartsWith(arg, `${p}=`) ||
+      (p !== '--experimental-config-file' && i > 0 && arr[i - 1] === p);
+  });
 }
 
 function getRunArgs(path, { forceExit,
diff --git a/src/node.cc b/src/node.cc
index 9bf1ff249abc8f..92d0402b7dfbaf 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -900,15 +900,21 @@ static ExitCode InitializeNodeWithArgsInternal(
   }
 
   std::string node_options_from_config;
-  if (auto path = per_process::config_reader.GetDataFromArgs(*argv)) {
-    switch (per_process::config_reader.ParseConfig(*path)) {
+  auto config_path = per_process::config_reader.GetDataFromArgs(argv);
+  if (per_process::config_reader.HasInvalidDefaultConfigFileArgument()) {
+    errors->push_back("--experimental-default-config-file does not take an "
+                      "argument");
+    return ExitCode::kInvalidCommandLineArgument;
+  }
+  if (config_path) {
+    switch (per_process::config_reader.ParseConfig(*config_path)) {
       case ParseResult::Valid:
         break;
       case ParseResult::InvalidContent:
-        errors->push_back(std::string(*path) + ": invalid content");
+        errors->push_back(std::string(*config_path) + ": invalid content");
         break;
       case ParseResult::FileError:
-        errors->push_back(std::string(*path) + ": not found");
+        errors->push_back(std::string(*config_path) + ": not found");
         break;
       default:
         UNREACHABLE();
diff --git a/src/node_config_file.cc b/src/node_config_file.cc
index ce89a51b7b97d3..925d71fecc52a3 100644
--- a/src/node_config_file.cc
+++ b/src/node_config_file.cc
@@ -2,39 +2,53 @@
 #include "debug_utils-inl.h"
 #include "simdjson.h"
 
-#include <string>
-
 namespace node {
 
+constexpr std::string_view kConfigFileFlag = "--experimental-config-file";
+constexpr std::string_view kDefaultConfigFileFlag =
+    "--experimental-default-config-file";
+constexpr std::string_view kDefaultConfigFileName = "node.config.json";
+
+inline bool HasEqualsPrefix(std::string_view arg, std::string_view flag) {
+  return arg.size() > flag.size() && arg.starts_with(flag) &&
+         arg[flag.size()] == '=';
+}
+
 std::optional<std::string_view> ConfigReader::GetDataFromArgs(
-    const std::vector<std::string>& args) {
-  constexpr std::string_view flag_path = "--experimental-config-file";
-  constexpr std::string_view default_file =
-      "--experimental-default-config-file";
-
-  bool has_default_config_file = false;
-
-  for (auto it = args.begin(); it != args.end(); ++it) {
-    if (*it == flag_path) {
-      // Case: "--experimental-config-file foo"
-      if (auto next = std::next(it); next != args.end()) {
-        return *next;
+    std::vector<std::string>* args) {
+  std::optional<std::string_view> result;
+  invalid_default_config_file_argument_ = false;
+
+  for (size_t i = 0; i < args->size(); ++i) {
+    std::string& arg = (*args)[i];
+
+    if (arg == kConfigFileFlag) {
+      // --experimental-config-file
+      arg = std::string(kConfigFileFlag) + "=" +
+            std::string(kDefaultConfigFileName);
+      result = kDefaultConfigFileName;
+    } else if (HasEqualsPrefix(arg, kConfigFileFlag)) {
+      // --experimental-config-file=path
+      std::string_view path =
+          std::string_view(arg).substr(kConfigFileFlag.size() + 1);
+      if (!path.empty()) {
+        result = path;
       }
-    } else if (it->starts_with(flag_path)) {
-      // Case: "--experimental-config-file=foo"
-      if (it->size() > flag_path.size() && (*it)[flag_path.size()] == '=') {
-        return std::string_view(*it).substr(flag_path.size() + 1);
-      }
-    } else if (*it == default_file || it->starts_with(default_file)) {
-      has_default_config_file = true;
+    } else if (arg == kDefaultConfigFileFlag) {
+      // --experimental-default-config-file
+      arg = std::string(kConfigFileFlag) + "=" +
+            std::string(kDefaultConfigFileName);
+      result = kDefaultConfigFileName;
+    } else if (HasEqualsPrefix(arg, kDefaultConfigFileFlag)) {
+      invalid_default_config_file_argument_ = true;
     }
   }
 
-  if (has_default_config_file) {
-    return "node.config.json";
-  }
+  return result;
+}
 
-  return std::nullopt;
+bool ConfigReader::HasInvalidDefaultConfigFileArgument() const {
+  return invalid_default_config_file_argument_;
 }
 
 ParseResult ConfigReader::ProcessOptionValue(
diff --git a/src/node_config_file.h b/src/node_config_file.h
index 82874cee8b583f..afe0e84765b8cb 100644
--- a/src/node_config_file.h
+++ b/src/node_config_file.h
@@ -30,7 +30,8 @@ class ConfigReader {
   ParseResult ParseConfig(const std::string_view& config_path);
 
   std::optional<std::string_view> GetDataFromArgs(
-      const std::vector<std::string>& args);
+      std::vector<std::string>* args);
+  bool HasInvalidDefaultConfigFileArgument() const;
 
   std::string GetNodeOptions();
   const std::vector<std::string>& GetNamespaceFlags() const;
@@ -53,6 +54,7 @@ class ConfigReader {
 
   std::vector<std::string> node_options_;
   std::vector<std::string> namespace_options_;
+  bool invalid_default_config_file_argument_ = false;
 
   // Cache for fast lookup of environment options
   std::unordered_map<std::string, options_parser::OptionMappingDetails>
diff --git a/src/node_options.cc b/src/node_options.cc
index a152d873052ff4..13f6977db84b24 100644
--- a/src/node_options.cc
+++ b/src/node_options.cc
@@ -900,11 +900,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             &EnvironmentOptions::optional_env_file);
   Implies("--env-file-if-exists", "[has_env_file_string]");
   AddOption("--experimental-config-file",
-            "set config file from supplied file",
-            &EnvironmentOptions::experimental_config_file_path);
-  AddOption("--experimental-default-config-file",
-            "set config file from default config file",
-            &EnvironmentOptions::experimental_default_config_file);
+            "set config file path",
+            &EnvironmentOptions::experimental_config_file_path,
+            kDisallowedInEnvvar);
+  AddAlias("--experimental-default-config-file", "--experimental-config-file");
   AddOption("--test",
             "launch test runner on startup",
             &EnvironmentOptions::test_runner,
diff --git a/src/node_options.h b/src/node_options.h
index 4d48b4e5752112..cbbd8375b71e28 100644
--- a/src/node_options.h
+++ b/src/node_options.h
@@ -273,7 +273,6 @@ class EnvironmentOptions : public Options {
   bool report_exclude_env = false;
   bool report_exclude_network = false;
   std::string experimental_config_file_path;
-  bool experimental_default_config_file = false;
 
   inline DebugOptions* get_debug_options() { return &debug_options_; }
   inline const DebugOptions& debug_options() const { return debug_options_; }
diff --git a/test/parallel/test-cli-node-options-docs.js b/test/parallel/test-cli-node-options-docs.js
index 80caa29d4263ef..534c99c04de964 100644
--- a/test/parallel/test-cli-node-options-docs.js
+++ b/test/parallel/test-cli-node-options-docs.js
@@ -122,5 +122,6 @@ for (const [, envVar, config] of nodeOptionsCC.matchAll(addOptionRE)) {
 
 // add alias handling
 manPagesOptions.delete('-trace-events-enabled');
+manPagesOptions.delete('-experimental-default-config-file');
 
 assert.strictEqual(manPagesOptions.size, 0, `Man page options not documented: ${[...manPagesOptions]}`);
diff --git a/test/parallel/test-cli-options-as-flags.js b/test/parallel/test-cli-options-as-flags.js
index ef42a7f94229d0..9fbc3c1733f5cd 100644
--- a/test/parallel/test-cli-options-as-flags.js
+++ b/test/parallel/test-cli-options-as-flags.js
@@ -55,8 +55,7 @@ describe('getOptionsAsFlagsFromBinding', () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
       '--expose-internals',
-      '--experimental-config-file',
-      configFile,
+      `--experimental-config-file=${configFile}`,
       fixtureFile,
     ]);
 
@@ -75,8 +74,7 @@ describe('getOptionsAsFlagsFromBinding', () => {
       '--no-warnings',
       '--expose-internals',
       '--stack-trace-limit=512',
-      '--experimental-config-file',
-      configFile,
+      `--experimental-config-file=${configFile}`,
       fixtureFile,
     ]);
 
diff --git a/test/parallel/test-config-file.js b/test/parallel/test-config-file.js
index ecba1fd430611e..334884d9ed893a 100644
--- a/test/parallel/test-config-file.js
+++ b/test/parallel/test-config-file.js
@@ -24,8 +24,7 @@ const onlyWithInspectorAndNodeOptions = {
 
 test('should handle non existing json', async () => {
   const result = await spawnPromisified(process.execPath, [
-    '--experimental-config-file',
-    'i-do-not-exist.json',
+    '--experimental-config-file=i-do-not-exist.json',
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /Cannot read configuration from i-do-not-exist\.json: no such file or directory/);
@@ -36,8 +35,7 @@ test('should handle non existing json', async () => {
 
 test('should handle empty json', async () => {
   const result = await spawnPromisified(process.execPath, [
-    '--experimental-config-file',
-    fixtures.path('rc/empty.json'),
+    `--experimental-config-file=${fixtures.path('rc/empty.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /Can't parse/);
@@ -49,8 +47,7 @@ test('should handle empty json', async () => {
 test('should handle empty object json', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/empty-object.json'),
+    `--experimental-config-file=${fixtures.path('rc/empty-object.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.strictEqual(result.stderr, '');
@@ -60,8 +57,7 @@ test('should handle empty object json', async () => {
 
 test('should parse boolean flag', onlyWithAmaroAndNodeOptions, async () => {
   const result = await spawnPromisified(process.execPath, [
-    '--experimental-config-file',
-    fixtures.path('rc/strip-types.json'),
+    `--experimental-config-file=${fixtures.path('rc/strip-types.json')}`,
     fixtures.path('typescript/ts/test-typescript.ts'),
   ]);
   assert.match(result.stderr, /--experimental-config-file is an experimental feature and might change at any time/);
@@ -71,8 +67,7 @@ test('should parse boolean flag', onlyWithAmaroAndNodeOptions, async () => {
 
 test('should parse boolean flag defaulted to true', onlyIfNodeOptionsSupport, async () => {
   const result = await spawnPromisified(process.execPath, [
-    '--experimental-config-file',
-    fixtures.path('rc/warnings-false.json'),
+    `--experimental-config-file=${fixtures.path('rc/warnings-false.json')}`,
     '-p', 'process.emitWarning("A warning")',
   ]);
   assert.strictEqual(result.stderr, '');
@@ -83,8 +78,7 @@ test('should parse boolean flag defaulted to true', onlyIfNodeOptionsSupport, as
 test('should throw an error when a flag is declared twice', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/override-property.json'),
+    `--experimental-config-file=${fixtures.path('rc/override-property.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /Option --strip-types is already defined/);
@@ -95,8 +89,7 @@ test('should throw an error when a flag is declared twice', async () => {
 test('should override env-file', onlyWithAmaroAndNodeOptions, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/strip-types.json'),
+    `--experimental-config-file=${fixtures.path('rc/strip-types.json')}`,
     '--env-file', fixtures.path('dotenv/node-options-no-tranform.env'),
     fixtures.path('typescript/ts/test-typescript.ts'),
   ]);
@@ -108,8 +101,7 @@ test('should override env-file', onlyWithAmaroAndNodeOptions, async () => {
 test('should not override NODE_OPTIONS', onlyWithAmaro, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/strip-types.json'),
+    `--experimental-config-file=${fixtures.path('rc/strip-types.json')}`,
     fixtures.path('typescript/ts/test-typescript.ts'),
   ], {
     env: {
@@ -126,8 +118,7 @@ test('should not override CLI flags', onlyWithAmaro, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
     '--no-strip-types',
-    '--experimental-config-file',
-    fixtures.path('rc/strip-types.json'),
+    `--experimental-config-file=${fixtures.path('rc/strip-types.json')}`,
     fixtures.path('typescript/ts/test-typescript.ts'),
   ]);
   assert.match(result.stderr, /SyntaxError/);
@@ -138,8 +129,7 @@ test('should not override CLI flags', onlyWithAmaro, async () => {
 test('should parse array flag correctly', onlyIfNodeOptionsSupport, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/import.json'),
+    `--experimental-config-file=${fixtures.path('rc/import.json')}`,
     '--eval', 'setTimeout(() => console.log("D"),99)',
   ]);
   assert.strictEqual(result.stderr, '');
@@ -150,8 +140,7 @@ test('should parse array flag correctly', onlyIfNodeOptionsSupport, async () =>
 test('should validate invalid array flag', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/invalid-import.json'),
+    `--experimental-config-file=${fixtures.path('rc/invalid-import.json')}`,
     '--eval', 'setTimeout(() => console.log("D"),99)',
   ]);
   assert.match(result.stderr, /invalid-import\.json: invalid content/);
@@ -162,8 +151,7 @@ test('should validate invalid array flag', async () => {
 test('should validate array flag as string', onlyIfNodeOptionsSupport, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/import-as-string.json'),
+    `--experimental-config-file=${fixtures.path('rc/import-as-string.json')}`,
     '--eval', 'setTimeout(() => console.log("B"),99)',
   ]);
   assert.strictEqual(result.stderr, '');
@@ -174,8 +162,7 @@ test('should validate array flag as string', onlyIfNodeOptionsSupport, async ()
 test('should throw at unknown flag', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/unknown-flag.json'),
+    `--experimental-config-file=${fixtures.path('rc/unknown-flag.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /Unknown or not allowed option some-unknown-flag for namespace nodeOptions/);
@@ -186,8 +173,7 @@ test('should throw at unknown flag', async () => {
 test('should throw at flag not available in NODE_OPTIONS', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/not-node-options-flag.json'),
+    `--experimental-config-file=${fixtures.path('rc/not-node-options-flag.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /Unknown or not allowed option test for namespace nodeOptions/);
@@ -198,8 +184,7 @@ test('should throw at flag not available in NODE_OPTIONS', async () => {
 test('unsigned flag should be parsed correctly', onlyIfNodeOptionsSupport, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/numeric.json'),
+    `--experimental-config-file=${fixtures.path('rc/numeric.json')}`,
     '-p', 'http.maxHeaderSize',
   ]);
   assert.strictEqual(result.stderr, '');
@@ -210,8 +195,7 @@ test('unsigned flag should be parsed correctly', onlyIfNodeOptionsSupport, async
 test('numeric flag should not allow negative values', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/negative-numeric.json'),
+    `--experimental-config-file=${fixtures.path('rc/negative-numeric.json')}`,
     '-p', 'http.maxHeaderSize',
   ]);
   assert.match(result.stderr, /Invalid value for --max-http-header-size/);
@@ -223,8 +207,7 @@ test('numeric flag should not allow negative values', async () => {
 test('v8 flag should not be allowed in config file', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/v8-flag.json'),
+    `--experimental-config-file=${fixtures.path('rc/v8-flag.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /V8 flag --abort-on-uncaught-exception is currently not supported/);
@@ -236,8 +219,7 @@ test('string flag should be parsed correctly', onlyIfNodeOptionsSupport, async (
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
     '--test',
-    '--experimental-config-file',
-    fixtures.path('rc/string.json'),
+    `--experimental-config-file=${fixtures.path('rc/string.json')}`,
     fixtures.path('rc/test.js'),
   ]);
   assert.strictEqual(result.stderr, '');
@@ -249,8 +231,7 @@ test('host port flag should be parsed correctly', onlyWithInspectorAndNodeOption
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
     '--expose-internals',
-    '--experimental-config-file',
-    fixtures.path('rc/host-port.json'),
+    `--experimental-config-file=${fixtures.path('rc/host-port.json')}`,
     '-p', 'require("internal/options").getOptionValue("--inspect-port").port',
   ]);
   assert.strictEqual(result.stderr, '');
@@ -261,8 +242,7 @@ test('host port flag should be parsed correctly', onlyWithInspectorAndNodeOption
 test('--inspect=true should be parsed correctly', onlyWithInspectorAndNodeOptions, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/inspect-true.json'),
+    `--experimental-config-file=${fixtures.path('rc/inspect-true.json')}`,
     '--inspect-port', '0',
     '-p', 'require("node:inspector").url()',
   ]);
@@ -274,8 +254,7 @@ test('--inspect=true should be parsed correctly', onlyWithInspectorAndNodeOption
 test('--inspect=false should be parsed correctly', { skip: !process.features.inspector }, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/inspect-false.json'),
+    `--experimental-config-file=${fixtures.path('rc/inspect-false.json')}`,
     '-p', 'require("node:inspector").url()',
   ]);
   assert.strictEqual(result.stderr, '');
@@ -286,8 +265,7 @@ test('--inspect=false should be parsed correctly', { skip: !process.features.ins
 test('no op flag should throw', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/no-op.json'),
+    `--experimental-config-file=${fixtures.path('rc/no-op.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /No-op flag --http-parser is currently not supported/);
@@ -299,8 +277,7 @@ test('no op flag should throw', async () => {
 test('should not allow users to sneak in a flag', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/sneaky-flag.json'),
+    `--experimental-config-file=${fixtures.path('rc/sneaky-flag.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /The number of NODE_OPTIONS doesn't match the number of flags in the config file/);
@@ -311,8 +288,7 @@ test('should not allow users to sneak in a flag', async () => {
 test('non object root', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/non-object-root.json'),
+    `--experimental-config-file=${fixtures.path('rc/non-object-root.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /Root value unexpected not an object for/);
@@ -323,8 +299,7 @@ test('non object root', async () => {
 test('non object node options', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/non-object-node-options.json'),
+    `--experimental-config-file=${fixtures.path('rc/non-object-node-options.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /"nodeOptions" value unexpected for/);
@@ -335,8 +310,7 @@ test('non object node options', async () => {
 test('should throw correct error when a json is broken', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/broken.json'),
+    `--experimental-config-file=${fixtures.path('rc/broken.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /Can't parse/);
@@ -348,8 +322,7 @@ test('should throw correct error when a json is broken', async () => {
 test('broken value in node_options', async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
-    '--experimental-config-file',
-    fixtures.path('rc/broken-node-options.json'),
+    `--experimental-config-file=${fixtures.path('rc/broken-node-options.json')}`,
     '-p', '"Hello, World!"',
   ]);
   assert.match(result.stderr, /Can't parse/);
@@ -371,12 +344,83 @@ test('should use node.config.json as default', onlyIfNodeOptionsSupport, async (
   assert.strictEqual(result.code, 0);
 });
 
-test('should override node.config.json when specificied', onlyIfNodeOptionsSupport, async () => {
+test('should use node.config.json when --experimental-config-file has no argument',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file',
+         '-p', 'http.maxHeaderSize',
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, '10\n');
+       assert.strictEqual(result.code, 0);
+     });
+
+test('should not treat the script path as a config file argument',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file',
+         fixtures.path('printA.js'),
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, 'A\n');
+       assert.strictEqual(result.code, 0);
+     });
+
+test('should treat a space-separated config file path as the script',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file',
+         fixtures.path('rc/empty.json'),
+         fixtures.path('printA.js'),
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.strictEqual(result.stdout, '');
+       assert.match(result.stderr, /SyntaxError/);
+       assert.match(result.stderr, /Unexpected end of JSON input/);
+       assert.doesNotMatch(result.stderr, /Can't parse/);
+       assert.doesNotMatch(result.stderr, /requires an argument/);
+       assert.strictEqual(result.code, 1);
+     });
+
+test('should error when --experimental-config-file= has empty argument',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file=',
+         '-p', 'http.maxHeaderSize',
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.match(result.stderr, /--experimental-config-file= requires an argument/);
+       assert.strictEqual(result.code, 9);
+     });
+
+test('should error when --experimental-default-config-file has an explicit argument',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-default-config-file=node.config.json',
+         '-p', 'http.maxHeaderSize',
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.match(result.stderr, /--experimental-default-config-file does not take an argument/);
+       assert.strictEqual(result.code, 9);
+     });
+
+test('should override node.config.json when specified', onlyIfNodeOptionsSupport, async () => {
   const result = await spawnPromisified(process.execPath, [
     '--no-warnings',
     '--experimental-default-config-file',
-    '--experimental-config-file',
-    fixtures.path('rc/default/override.json'),
+    `--experimental-config-file=${fixtures.path('rc/default/override.json')}`,
     '-p', 'http.maxHeaderSize',
   ], {
     cwd: fixtures.path('rc/default'),
@@ -385,6 +429,46 @@ test('should override node.config.json when specificied', onlyIfNodeOptionsSuppo
   assert.strictEqual(result.stdout, '20\n');
   assert.strictEqual(result.code, 0);
 });
+
+test('should work with --experimental-config-file=path',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         `--experimental-config-file=${fixtures.path('rc/default/node.config.json')}`,
+         '-p', 'http.maxHeaderSize',
+       ]);
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, '10\n');
+       assert.strictEqual(result.code, 0);
+     });
+
+test('should use last config file when multiple are specified',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         `--experimental-config-file=${fixtures.path('rc/default/node.config.json')}`,
+         `--experimental-config-file=${fixtures.path('rc/default/override.json')}`,
+         '-p', 'http.maxHeaderSize',
+       ]);
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, '20\n');
+       assert.strictEqual(result.code, 0);
+     });
+
+test('should use default when next argument starts with dash',
+     onlyIfNodeOptionsSupport, async () => {
+       const result = await spawnPromisified(process.execPath, [
+         '--no-warnings',
+         '--experimental-config-file',
+         '-p', 'http.maxHeaderSize',
+       ], {
+         cwd: fixtures.path('rc/default'),
+       });
+       assert.strictEqual(result.stderr, '');
+       assert.strictEqual(result.stdout, '10\n');
+       assert.strictEqual(result.code, 0);
+     });
+
 // Skip on windows because it doesn't support chmod changing read permissions
 // Also skip if user is root because it would have read permissions anyway
 test('should throw an error when the file is non readable', {
@@ -413,8 +497,7 @@ describe('namespace-scoped options', () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
       '--expose-internals',
-      '--experimental-config-file',
-      fixtures.path('rc/namespaced/node.config.json'),
+      `--experimental-config-file=${fixtures.path('rc/namespaced/node.config.json')}`,
       '--no-test',
       '-p', 'require("internal/options").getOptionValue("--test-isolation")',
     ]);
@@ -426,8 +509,7 @@ describe('namespace-scoped options', () => {
   it('should throw an error when a namespace-scoped option is not recognised', async () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
-      '--experimental-config-file',
-      fixtures.path('rc/unknown-flag-namespace.json'),
+      `--experimental-config-file=${fixtures.path('rc/unknown-flag-namespace.json')}`,
       '-p', '"Hello, World!"',
     ]);
     assert.match(result.stderr, /Unknown or not allowed option unknown-flag for namespace test/);
@@ -438,8 +520,7 @@ describe('namespace-scoped options', () => {
   it('should not throw an error when a namespace is not recognised', async () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
-      '--experimental-config-file',
-      fixtures.path('rc/unknown-namespace.json'),
+      `--experimental-config-file=${fixtures.path('rc/unknown-namespace.json')}`,
       '-p', '"Hello, World!"',
     ]);
     assert.strictEqual(result.stderr, '');
@@ -450,8 +531,7 @@ describe('namespace-scoped options', () => {
   it('should handle an empty namespace valid namespace', async () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
-      '--experimental-config-file',
-      fixtures.path('rc/empty-valid-namespace.json'),
+      `--experimental-config-file=${fixtures.path('rc/empty-valid-namespace.json')}`,
       '-p', '"Hello, World!"',
     ]);
     assert.strictEqual(result.stderr, '');
@@ -463,8 +543,7 @@ describe('namespace-scoped options', () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
       '--expose-internals',
-      '--experimental-config-file',
-      fixtures.path('rc/override-node-option-with-namespace.json'),
+      `--experimental-config-file=${fixtures.path('rc/override-node-option-with-namespace.json')}`,
       '-p', 'require("internal/options").getOptionValue("--test-isolation")',
     ]);
     assert.match(result.stderr, /Option --test-isolation is already defined/);
@@ -476,8 +555,7 @@ describe('namespace-scoped options', () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
       '--expose-internals',
-      '--experimental-config-file',
-      fixtures.path('rc/override-namespace.json'),
+      `--experimental-config-file=${fixtures.path('rc/override-namespace.json')}`,
       '-p', 'require("internal/options").getOptionValue("--test-isolation")',
     ]);
     assert.match(result.stderr, /Option --test-isolation is already defined/);
@@ -490,8 +568,7 @@ describe('namespace-scoped options', () => {
       '--no-warnings',
       '--expose-internals',
       '--test-isolation', 'process',
-      '--experimental-config-file',
-      fixtures.path('rc/namespaced/node.config.json'),
+      `--experimental-config-file=${fixtures.path('rc/namespaced/node.config.json')}`,
       '--no-test',
       '-p', 'require("internal/options").getOptionValue("--test-isolation")',
     ]);
@@ -506,8 +583,7 @@ describe('namespace-scoped options', () => {
       '--expose-internals',
       '--test-coverage-exclude', 'cli-pattern1',
       '--test-coverage-exclude', 'cli-pattern2',
-      '--experimental-config-file',
-      fixtures.path('rc/namespace-with-array.json'),
+      `--experimental-config-file=${fixtures.path('rc/namespace-with-array.json')}`,
       '--no-test',
       '-p', 'JSON.stringify(require("internal/options").getOptionValue("--test-coverage-exclude"))',
     ]);
@@ -529,8 +605,7 @@ describe('namespace-scoped options', () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
       '--expose-internals',
-      '--experimental-config-file',
-      fixtures.path('rc/namespace-with-disallowed-envvar.json'),
+      `--experimental-config-file=${fixtures.path('rc/namespace-with-disallowed-envvar.json')}`,
       '--no-test',
       '-p', 'require("internal/options").getOptionValue("--test-concurrency")',
     ]);
@@ -546,8 +621,7 @@ describe('namespace-scoped options', () => {
       '--no-warnings',
       '--expose-internals',
       '--test-concurrency', '2',
-      '--experimental-config-file',
-      fixtures.path('rc/namespace-with-disallowed-envvar.json'),
+      `--experimental-config-file=${fixtures.path('rc/namespace-with-disallowed-envvar.json')}`,
       '--no-test',
       '-p', 'require("internal/options").getOptionValue("--test-concurrency")',
     ]);
@@ -559,8 +633,7 @@ describe('namespace-scoped options', () => {
   it('should throw an error for removed "testRunner" namespace', async () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
-      '--experimental-config-file',
-      fixtures.path('rc/deprecated-testrunner-namespace.json'),
+      `--experimental-config-file=${fixtures.path('rc/deprecated-testrunner-namespace.json')}`,
       '-p', '"Hello, World!"',
     ]);
     assert.match(result.stderr, /the "testRunner" namespace has been removed\. Use "test" instead\./);
@@ -571,8 +644,7 @@ describe('namespace-scoped options', () => {
   it('should automatically enable --test flag when test namespace is present', async () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
-      '--experimental-config-file',
-      fixtures.path('rc/namespaced/node.config.json'),
+      `--experimental-config-file=${fixtures.path('rc/namespaced/node.config.json')}`,
       fixtures.path('rc/test.js'),
     ]);
     assert.strictEqual(result.code, 0);
@@ -583,8 +655,7 @@ describe('namespace-scoped options', () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
       '--expose-internals',
-      '--experimental-config-file',
-      fixtures.path('rc/permission-namespace.json'),
+      `--experimental-config-file=${fixtures.path('rc/permission-namespace.json')}`,
       '-p', 'require("internal/options").getOptionValue("--permission")',
     ]);
     assert.strictEqual(result.stderr, '');
@@ -596,8 +667,7 @@ describe('namespace-scoped options', () => {
     const result = await spawnPromisified(process.execPath, [
       '--no-warnings',
       '--expose-internals',
-      '--experimental-config-file',
-      fixtures.path('rc/test-namespace-explicit-false.json'),
+      `--experimental-config-file=${fixtures.path('rc/test-namespace-explicit-false.json')}`,
       '-p', 'require("internal/options").getOptionValue("--test")',
     ]);
     assert.strictEqual(result.stderr, '');
diff --git a/test/parallel/test-permission-config-file.mjs b/test/parallel/test-permission-config-file.mjs
index 595c4b6f91bcf5..bfa9d6b01896e2 100644
--- a/test/parallel/test-permission-config-file.mjs
+++ b/test/parallel/test-permission-config-file.mjs
@@ -13,8 +13,7 @@ describe('Permission model config file support', () => {
     {
       const result = await spawnPromisified(process.execPath, [
         '--permission',
-        '--experimental-config-file',
-        readOnlyConfigPath,
+        `--experimental-config-file=${readOnlyConfigPath}`,
         readTestPath,
       ]);
       assert.strictEqual(result.code, 0);
@@ -23,8 +22,7 @@ describe('Permission model config file support', () => {
     {
       const result = await spawnPromisified(process.execPath, [
         '--permission',
-        '--experimental-config-file',
-        readWriteConfigPath,
+        `--experimental-config-file=${readWriteConfigPath}`,
         writeTestPath,
       ]);
       assert.strictEqual(result.code, 0);
@@ -33,8 +31,7 @@ describe('Permission model config file support', () => {
     {
       const result = await spawnPromisified(process.execPath, [
         '--permission',
-        '--experimental-config-file',
-        readOnlyConfigPath,
+        `--experimental-config-file=${readOnlyConfigPath}`,
         writeTestPath,
       ]);
       assert.strictEqual(result.code, 1);
@@ -50,8 +47,7 @@ describe('Permission model config file support', () => {
     {
       const result = await spawnPromisified(process.execPath, [
         '--permission',
-        '--experimental-config-file',
-        configPath,
+        `--experimental-config-file=${configPath}`,
         childTestPath,
       ]);
       assert.strictEqual(result.code, 0);
@@ -60,8 +56,7 @@ describe('Permission model config file support', () => {
     {
       const result = await spawnPromisified(process.execPath, [
         '--permission',
-        '--experimental-config-file',
-        readOnlyConfigPath,
+        `--experimental-config-file=${readOnlyConfigPath}`,
         childTestPath,
       ]);
       assert.strictEqual(result.code, 1, result.stderr);
@@ -76,8 +71,7 @@ describe('Permission model config file support', () => {
     {
       const result = await spawnPromisified(process.execPath, [
         '--permission',
-        '--experimental-config-file',
-        configPath,
+        `--experimental-config-file=${configPath}`,
         '-p',
         'process.permission.has("net") && process.permission.has("inspector")',
       ]);
@@ -88,8 +82,7 @@ describe('Permission model config file support', () => {
     {
       const result = await spawnPromisified(process.execPath, [
         '--permission',
-        '--experimental-config-file',
-        readOnlyConfigPath,
+        `--experimental-config-file=${readOnlyConfigPath}`,
         '-p',
         'process.permission.has("net") + process.permission.has("inspector")',
       ]);
@@ -103,8 +96,7 @@ describe('Permission model config file support', () => {
 
     const result = await spawnPromisified(process.execPath, [
       '--permission',
-      '--experimental-config-file',
-      configPath,
+      `--experimental-config-file=${configPath}`,
       '--allow-fs-read=*',
       '-p',
       'process.permission.has("addon") && process.permission.has("wasi")',
@@ -118,8 +110,7 @@ describe('Permission model config file support', () => {
 
     const result = await spawnPromisified(process.execPath, [
       '--permission',
-      '--experimental-config-file',
-      configPath,
+      `--experimental-config-file=${configPath}`,
       '--allow-child-process',
       '--allow-fs-write=*',
       '-p',
diff --git a/test/parallel/test-runner-cli.js b/test/parallel/test-runner-cli.js
index ffa4a00206243a..f563d67d1a9a41 100644
--- a/test/parallel/test-runner-cli.js
+++ b/test/parallel/test-runner-cli.js
@@ -431,30 +431,37 @@ for (const isolation of ['none', 'process']) {
 }
 
 {
-  // Should not propagate --experimental-config-file option to sub test in isolation process
+  // Should not propagate config file options to sub tests in isolation process.
   const fixturePath = join(testFixtures, 'options-propagation');
-  const args = [
-    '--test-reporter=tap',
-    '--no-warnings',
-    `--experimental-config-file=node.config.json`,
-    '--expose-internals',
-    '--test',
+  const configFlagVariants = [
+    ['--experimental-config-file=node.config.json'],
+    ['--experimental-config-file'],
+    ['--experimental-default-config-file'],
   ];
-  const child = spawnSync(process.execPath, args, { cwd: fixturePath });
 
-  assert.strictEqual(child.stderr.toString(), '');
-  const stdout = child.stdout.toString();
+  for (const configArgs of configFlagVariants) {
+    const args = [
+      '--test-reporter=tap',
+      '--no-warnings',
+      ...configArgs,
+      '--expose-internals',
+      '--test',
+    ];
+    const child = spawnSync(process.execPath, args, { cwd: fixturePath });
 
-  assert.match(stdout, /tests 1/);
-  assert.match(stdout, /suites 0/);
-  assert.match(stdout, /pass 1/);
-  assert.match(stdout, /fail 0/);
-  assert.match(stdout, /cancelled 0/);
-  assert.match(stdout, /skipped 0/);
-  assert.match(stdout, /todo 0/);
+    assert.strictEqual(child.stderr.toString(), '');
+    const stdout = child.stdout.toString();
 
+    assert.match(stdout, /tests 1/);
+    assert.match(stdout, /suites 0/);
+    assert.match(stdout, /pass 1/);
+    assert.match(stdout, /fail 0/);
+    assert.match(stdout, /cancelled 0/);
+    assert.match(stdout, /skipped 0/);
+    assert.match(stdout, /todo 0/);
 
-  assert.strictEqual(child.status, 0);
+    assert.strictEqual(child.status, 0);
+  }
 }
 
 {
diff --git a/test/parallel/test-runner-flag-propagation.js b/test/parallel/test-runner-flag-propagation.js
index f4e9849cce77d0..055d8b6d67c9b5 100644
--- a/test/parallel/test-runner-flag-propagation.js
+++ b/test/parallel/test-runner-flag-propagation.js
@@ -15,8 +15,10 @@ const runner = path.join(fixtureDir, 'runner.mjs');
 describe('test runner flag propagation', () => {
   describe('via command line', () => {
     const flagPropagationTests = [
-      ['--experimental-config-file', 'node.config.json', ''],
-      ['--experimental-default-config-file', '', false],
+      ['--experimental-config-file=node.config.json', '', '', '--experimental-config-file',
+       'should not propagate --experimental-config-file to child tests'],
+      ['--experimental-default-config-file', '', '', '--experimental-config-file',
+       'should not propagate --experimental-default-config-file to child tests'],
       ['--env-file', '.env', '.env'],
       ['--env-file-if-exists', '.env', '.env'],
       ['--test-concurrency', '2', '2'],
@@ -32,8 +34,11 @@ describe('test runner flag propagation', () => {
       ['--require', './index.js', './index.js'],
     ];
 
-    for (const [flagName, testValue, expectedValue] of flagPropagationTests) {
-      const testDescription = `should propagate ${flagName} to child tests as expected`;
+    for (const [flagName,
+                testValue,
+                expectedValue,
+                propagatedFlag = flagName,
+                testDescription = `should propagate ${flagName} to child tests as expected`] of flagPropagationTests) {
 
       it(testDescription, () => {
         const args = [
@@ -45,7 +50,7 @@ describe('test runner flag propagation', () => {
           // Use the runner fixture
           runner,
           // Pass parameters to the fixture
-          `--flag=${flagName}`,
+          `--flag=${propagatedFlag}`,
           `--expected=${expectedValue}`,
           `--description="${testDescription}"`,
         ].filter(Boolean);
diff --git a/test/sequential/test-watch-mode.mjs b/test/sequential/test-watch-mode.mjs
index 39ad7ef72ada00..707210a021f944 100644
--- a/test/sequential/test-watch-mode.mjs
+++ b/test/sequential/test-watch-mode.mjs
@@ -826,7 +826,7 @@ process.on('message', (message) => {
     const file = createTmpFile();
     const configFile = createTmpFile(JSON.stringify({ watch: { 'watch': true } }), '.json');
     const { stderr, stdout } = await runWriteSucceed({
-      file, watchedFile: file, args: ['--experimental-config-file', configFile, file], options: {
+      file, watchedFile: file, args: [`--experimental-config-file=${configFile}`, file], options: {
         timeout: 10000,
       },
     });
@@ -850,7 +850,7 @@ process.on('message', (message) => {
     const watchedFile = createTmpFile('', '.js', dir);
     const configFile = createTmpFile(JSON.stringify({ watch: { 'watch-path': [dir] } }), '.json', dir);
 
-    const args = ['--experimental-config-file', configFile, file];
+    const args = [`--experimental-config-file=${configFile}`, file];
     const { stderr, stdout } = await runWriteSucceed({ file, watchedFile, args });
 
     assert.strictEqual(stderr, '');