test_runner: don't parse TAP from stderr

lib/internal/test_runner/runner.js

@@ -241,22 +241,29 @@ function runTestFile(path, root, inspectPort, filesWatcher) {
       err = error;
     });
 
-    if (isUsingInspector()) {
-      const rl = createInterface({ input: child.stderr });
-      rl.on('line', (line) => {
-        if (isInspectorMessage(line)) {
-          process.stderr.write(line + '\n');
-        }
-      });
-    }
-
-    const parser = new TapParser();
-    child.stderr.pipe(parser).on('data', (ast) => {
-      if (ast.lexeme && isInspectorMessage(ast.lexeme)) {
-        process.stderr.write(ast.lexeme + '\n');
+    const rl = createInterface({ input: child.stderr });
+    rl.on('line', (line) => {
+      if (isInspectorMessage(line)) {
+        process.stderr.write(line + '\n');
+        return;
       }
+
+      // stderr cannot be treated as TAP, per the spec. However, we want to
+      // surface stderr lines as TAP diagnostics to improve the DX. Inject
+      // each line into the test output as an unknown token as if it came
+      // from the TAP parser.
+      const node = {
+        kind: TokenKind.UNKNOWN,
+        node: {
+          value: line,
+        },
+      };
+
+      subtest.addToReport(node);
     });
 
+    const parser = new TapParser();
+
     child.stdout.pipe(parser).on('data', (ast) => {
       subtest.addToReport(ast);
     });

lib/internal/util/inspector.js

@@ -16,7 +16,7 @@ const { validatePort } = require('internal/validators');
 const kMinPort = 1024;
 const kMaxPort = 65535;
 const kInspectArgRegex = /--inspect(?:-brk|-port)?|--debug-port/;
-const kInspectMsgRegex = /Debugger listening on ws:\/\/\[?(.+?)\]?:(\d+)\/|Debugger attached|Waiting for the debugger to disconnect\.\.\./;
+const kInspectMsgRegex = /Debugger listening on ws:\/\/\[?(.+?)\]?:(\d+)\/|For help, see: https:\/\/nodejs\.org\/en\/docs\/inspector|Debugger attached|Waiting for the debugger to disconnect\.\.\./;
 
 const _isUsingInspector = new SafeWeakMap();
 function isUsingInspector(execArgv = process.execArgv) {

test/fixtures/test-runner/user-logs.js

@@ -0,0 +1,20 @@
+'use strict';
+const test = require('node:test');
+
+console.error('stderr', 1);
+
+test('a test', async () => {
+  console.error('stderr', 2);
+  await new Promise((resolve) => {
+    console.log('stdout', 3);
+    setTimeout(() => {
+      // This should not be sent to the TAP parser.
+      console.error('not ok 1 - fake test');
+      resolve();
+      console.log('stdout', 4);
+    }, 2);
+  });
+  console.error('stderr', 5);
+});
+
+console.error('stderr', 6);

test/parallel/test-runner-cli.js

@@ -168,3 +168,29 @@ const testFixtures = fixtures.path('test-runner');
   assert.match(stdout, /# pass 2/);
   assert.match(stdout, /# fail 1/);
 }
+
+{
+  // Test user logging in tests.
+  const args = [
+    '--test',
+    'test/fixtures/test-runner/user-logs.js',
+  ];
+  const child = spawnSync(process.execPath, args);
+
+  assert.strictEqual(child.status, 0);
+  assert.strictEqual(child.signal, null);
+  assert.strictEqual(child.stderr.toString(), '');
+  const stdout = child.stdout.toString();
+  assert.match(stdout, /# Subtest: .+user-logs\.js/);
+  assert.match(stdout, / {4}# stderr 1/);
+  assert.match(stdout, / {4}# stderr 2/);
+  assert.match(stdout, / {4}# stdout 3/);
+  assert.match(stdout, / {4}# stderr 6/);
+  assert.match(stdout, / {4}# not ok 1 - fake test/);
+  assert.match(stdout, / {4}# stderr 5/);
+  assert.match(stdout, / {4}# stdout 4/);
+  assert.match(stdout, / {4}# Subtest: a test/);
+  assert.match(stdout, / {4}ok 1 - a test/);
+  assert.match(stdout, /# tests 1/);
+  assert.match(stdout, /# pass 1/);
+}