nodejs
diff --git a/‎lib/internal/test_runner/test.js‎
Lines changed: 19 additions & 9 deletions b/‎lib/internal/test_runner/test.js‎
Lines changed: 19 additions & 9 deletions
diff --git a/‎test/parallel/test-runner-option-validation.js‎
Lines changed: 11 additions & 0 deletions b/‎test/parallel/test-runner-option-validation.js‎
Lines changed: 11 additions & 0 deletions
@@ -19,6 +19,7 @@ const { once } = require('events');
 const { AbortController } = require('internal/abort_controller');
 const {
   codes: {
+    ERR_INVALID_ARG_TYPE,
     ERR_TEST_FAILURE,
   },
   kIsNodeError,
@@ -33,9 +34,9 @@ const {
 } = require('internal/util');
 const { isPromise } = require('internal/util/types');
 const {
-  isUint32,
   validateAbortSignal,
   validateNumber,
+  validateUint32,
 } = require('internal/validators');
 const { setTimeout } = require('timers/promises');
 const { TIMEOUT_MAX } = require('internal/timers');
@@ -149,14 +150,23 @@ class Test extends AsyncResource {
       this.timeout = parent.timeout;
     }
 
-    if (isUint32(concurrency) && concurrency !== 0) {
-      this.concurrency = concurrency;
-    } else if (typeof concurrency === 'boolean') {
-      if (concurrency) {
-        this.concurrency = isTestRunner ? MathMax(cpus().length - 1, 1) : Infinity;
-      } else {
-        this.concurrency = 1;
-      }
+    switch (typeof concurrency) {
+      case 'number':
+        validateUint32(concurrency, 'options.concurrency', 1);
+        this.concurrency = concurrency;
+        break;
+
+      case 'boolean':
+        if (concurrency) {
+          this.concurrency = isTestRunner ? MathMax(cpus().length - 1, 1) : Infinity;
+        } else {
+          this.concurrency = 1;
+        }
+        break;
+
+      default:
+        if (concurrency != null)
+          throw new ERR_INVALID_ARG_TYPE('options.concurrency', ['boolean', 'number'], concurrency);
     }
 
     if (timeout != null && timeout !== Infinity) {
 
@@ -13,3 +13,14 @@ const test = require('node:test');
   // Valid values should not throw.
   test({ timeout });
 });
+
+[Symbol(), {}, [], () => {}, 1n, '1'].forEach((concurrency) => {
+  assert.throws(() => test({ concurrency }), { code: 'ERR_INVALID_ARG_TYPE' });
+});
+[-1, 0, 1.1, -Infinity, NaN, 2 ** 33, Number.MAX_SAFE_INTEGER].forEach((concurrency) => {
+  assert.throws(() => test({ concurrency }), { code: 'ERR_OUT_OF_RANGE' });
+});
+[null, undefined, 1, 2 ** 31, true, false].forEach((concurrency) => {
+  // Valid values should not throw.
+  test({ concurrency });
+});