diff --git a/front_end/core/sdk/CPUThrottlingManager.test.ts b/front_end/core/sdk/CPUThrottlingManager.test.ts
index 438ec1510f..cfc1a8a0aa 100644
--- a/front_end/core/sdk/CPUThrottlingManager.test.ts
+++ b/front_end/core/sdk/CPUThrottlingManager.test.ts
@@ -2,40 +2,48 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import {describeWithRealConnection} from '../../testing/RealConnection.js';
+import {createTarget} from '../../testing/EnvironmentHelpers.js';
+import {describeWithMockConnection, setMockConnectionResponseHandler} from '../../testing/MockConnection.js';
 
 import * as SDK from './sdk.js';
 
-describeWithRealConnection('CPUThrottlingManager', () => {
-  it('can get the current hardwareConcurrency.', async () => {
-    const manager = SDK.CPUThrottlingManager.CPUThrottlingManager.instance();
-    const concurrency = await manager.getHardwareConcurrency();
-    assert.deepEqual(concurrency, navigator.hardwareConcurrency);
+describeWithMockConnection('CPUThrottlingManager', () => {
+  let target: SDK.Target.Target;
+
+  beforeEach(() => {
+    // We need one target since CPUThrottlingManager gets it from TargetManager.
+    target = createTarget();
   });
 
-  it('can set the current hardwareConcurrency.', async () => {
+  it('can get the current hardwareConcurrency.', async () => {
+    setMockConnectionResponseHandler('Runtime.evaluate', ({expression}) => {
+      assert.strictEqual(expression, 'navigator.hardwareConcurrency');
+      return ({getError: () => undefined, result: {value: 42}});
+    });
+
+    const manager = SDK.CPUThrottlingManager.CPUThrottlingManager.instance();
+    const concurrency = await manager.getHardwareConcurrency();
+    assert.strictEqual(concurrency, 42);
+  });
+
+  it('can set the current hardwareConcurrency', async () => {
+    const cdpStub = sinon.stub(target.emulationAgent(), 'invoke_setHardwareConcurrencyOverride').resolves();
+
     const manager = SDK.CPUThrottlingManager.CPUThrottlingManager.instance();
-    const nativeConcurrency = navigator.hardwareConcurrency;
     manager.setHardwareConcurrency(5);
-    {
-      const concurrency = await manager.getHardwareConcurrency();
-      assert.deepEqual(concurrency, 5);
-      assert.notDeepEqual(concurrency, nativeConcurrency);
-    }
-    {
-      manager.setHardwareConcurrency(0);
-      const concurrency = await manager.getHardwareConcurrency();
-      assert.deepEqual(concurrency, 5);
-    }
-    {
-      manager.setHardwareConcurrency(-1);
-      const concurrency = await manager.getHardwareConcurrency();
-      assert.deepEqual(concurrency, 5);
-    }
-    {
-      manager.setHardwareConcurrency(2 * nativeConcurrency);
-      const concurrency = await manager.getHardwareConcurrency();
-      assert.deepEqual(concurrency, 2 * nativeConcurrency);
-    }
+
+    assert.isTrue(cdpStub.calledOnce);
+    assert.isTrue(cdpStub.calledWithExactly({hardwareConcurrency: 5}));
+  });
+
+  it('does not set concurrency to 0 or negative numbers', async () => {
+    const cdpStub = sinon.stub(target.emulationAgent(), 'invoke_setHardwareConcurrencyOverride').resolves();
+
+    const manager = SDK.CPUThrottlingManager.CPUThrottlingManager.instance();
+    manager.setHardwareConcurrency(0);
+    assert.isFalse(cdpStub.called);
+
+    manager.setHardwareConcurrency(-1);
+    assert.isFalse(cdpStub.called);
   });
 });