module: add warnings for experimental flags

PR-URL: https://github.com/nodejs/node/pull/30617
Fixes: https://github.com/nodejs/node/issues/30600
Reviewed-By: Guy Bedford <guybedford@gmail.com>

8 files changed, 99 insertions, 2 deletions

diff --git a/test/common/fixtures.mjs b/test/common/fixtures.mjs
new file mode 100644
index 0000000000..3eeef6d607
--- /dev/null
+++ b/test/common/fixtures.mjs
@@ -0,0 +1,16 @@
+/* eslint-disable node-core/require-common-first, node-core/required-modules */
+import fixtures from './fixtures.js';
+
+const {
+  fixturesDir,
+  path,
+  readSync,
+  readKey,
+} = fixtures;
+
+export {
+  fixturesDir,
+  path,
+  readSync,
+  readKey,
+};
diff --git a/test/es-module/test-esm-exports.mjs b/test/es-module/test-esm-exports.mjs
index a361bafaa8..73a86793a2 100644
--- a/test/es-module/test-esm-exports.mjs
+++ b/test/es-module/test-esm-exports.mjs
@@ -1,6 +1,8 @@
 // Flags: --experimental-modules
 import { mustCall } from '../common/index.mjs';
+import { path } from '../common/fixtures.mjs';
 import { ok, deepStrictEqual, strictEqual } from 'assert';
+import { spawn } from 'child_process';
 
 import { requireFixture, importFixture } from '../fixtures/pkgexports.mjs';
 import fromInside from '../fixtures/node_modules/pkgexports/lib/hole.js';
@@ -149,3 +151,33 @@ function assertIncludes(actual, expected) {
   ok(actual.toString().indexOf(expected) !== -1,
      `${JSON.stringify(actual)} includes ${JSON.stringify(expected)}`);
 }
+
+// Test warning message
+[
+  [
+    '--experimental-conditional-exports',
+    '/es-modules/conditional-exports.js',
+    'Conditional exports',
+  ],
+  [
+    '--experimental-resolve-self',
+    '/node_modules/pkgexports/resolve-self.js',
+    'Package name self resolution',
+  ],
+].forEach(([flag, file, message]) => {
+  const child = spawn(process.execPath, [flag, path(file)]);
+
+  let stderr = '';
+  child.stderr.setEncoding('utf8');
+  child.stderr.on('data', (data) => {
+    stderr += data;
+  });
+  child.on('close', (code, signal) => {
+    strictEqual(code, 0);
+    strictEqual(signal, null);
+    ok(stderr.toString().includes(
+      `ExperimentalWarning: ${message} is an experimental feature. ` +
+      'This feature could change at any time'
+    ));
+  });
+});
diff --git a/test/es-module/test-esm-json.mjs b/test/es-module/test-esm-json.mjs
index 9dd33f26b5..ddcc7cb33e 100644
--- a/test/es-module/test-esm-json.mjs
+++ b/test/es-module/test-esm-json.mjs
@@ -1,7 +1,29 @@
 // Flags: --experimental-json-modules
 import '../common/index.mjs';
-import { strictEqual } from 'assert';
+import { path } from '../common/fixtures.mjs';
+import { strictEqual, ok } from 'assert';
+import { spawn } from 'child_process';
 
 import secret from '../fixtures/experimental.json';
 
 strictEqual(secret.ofLife, 42);
+
+// Test warning message
+const child = spawn(process.execPath, [
+  '--experimental-json-modules',
+  path('/es-modules/json-modules.mjs')
+]);
+
+let stderr = '';
+child.stderr.setEncoding('utf8');
+child.stderr.on('data', (data) => {
+  stderr += data;
+});
+child.on('close', (code, signal) => {
+  strictEqual(code, 0);
+  strictEqual(signal, null);
+  ok(stderr.toString().includes(
+    'ExperimentalWarning: Importing JSON modules is an experimental feature. ' +
+    'This feature could change at any time'
+  ));
+});
diff --git a/test/es-module/test-esm-wasm.mjs b/test/es-module/test-esm-wasm.mjs
index 46df5994af..b2218ce2f0 100644
--- a/test/es-module/test-esm-wasm.mjs
+++ b/test/es-module/test-esm-wasm.mjs
@@ -1,8 +1,10 @@
 // Flags: --experimental-wasm-modules
 import '../common/index.mjs';
+import { path } from '../common/fixtures.mjs';
 import { add, addImported } from '../fixtures/es-modules/simple.wasm';
 import { state } from '../fixtures/es-modules/wasm-dep.mjs';
-import { strictEqual } from 'assert';
+import { strictEqual, ok } from 'assert';
+import { spawn } from 'child_process';
 
 strictEqual(state, 'WASM Start Executed');
 
@@ -13,3 +15,23 @@ strictEqual(addImported(0), 42);
 strictEqual(state, 'WASM JS Function Executed');
 
 strictEqual(addImported(1), 43);
+
+// Test warning message
+const child = spawn(process.execPath, [
+  '--experimental-wasm-modules',
+  path('/es-modules/wasm-modules.mjs')
+]);
+
+let stderr = '';
+child.stderr.setEncoding('utf8');
+child.stderr.on('data', (data) => {
+  stderr += data;
+});
+child.on('close', (code, signal) => {
+  strictEqual(code, 0);
+  strictEqual(signal, null);
+  ok(stderr.toString().includes(
+    'ExperimentalWarning: Importing Web Assembly modules is ' +
+    'an experimental feature. This feature could change at any time'
+  ));
+});
diff --git a/test/fixtures/es-modules/conditional-exports.js b/test/fixtures/es-modules/conditional-exports.js
new file mode 100644
index 0000000000..b480078bfc
--- /dev/null
+++ b/test/fixtures/es-modules/conditional-exports.js
@@ -0,0 +1 @@
+require('pkgexports/condition')
diff --git a/test/fixtures/es-modules/json-modules.mjs b/test/fixtures/es-modules/json-modules.mjs
new file mode 100644
index 0000000000..fa3f936bac
--- /dev/null
+++ b/test/fixtures/es-modules/json-modules.mjs
@@ -0,0 +1 @@
+import secret from '../experimental.json';
diff --git a/test/fixtures/es-modules/wasm-modules.mjs b/test/fixtures/es-modules/wasm-modules.mjs
new file mode 100644
index 0000000000..c56e6a926b
--- /dev/null
+++ b/test/fixtures/es-modules/wasm-modules.mjs
@@ -0,0 +1,2 @@
+import { add, addImported } from './simple.wasm';
+import { state } from './wasm-dep.mjs';
diff --git a/test/fixtures/node_modules/pkgexports/resolve-self.js b/test/fixtures/node_modules/pkgexports/resolve-self.js
new file mode 100644
index 0000000000..7bd3526aaa
--- /dev/null
+++ b/test/fixtures/node_modules/pkgexports/resolve-self.js
@@ -0,0 +1 @@
+require('@pkgexports/name/valid-cjs')