---
description: Use the Node.js test module MockTracker API in Cloudflare Workers for tracking and managing mock objects.
title: test
image: https://developers.cloudflare.com/og-docs.png
---

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# test

Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://fix-ai-gateway-guardrails-streaming-docs.previews.developers.cloudflare.com/workers/runtime-apis/nodejs/test/index.md)|[Agent setup](https://fix-ai-gateway-guardrails-streaming-docs.previews.developers.cloudflare.com/agent-setup/)

Note

For compatibility dates of `2026-08-04` or later, Workers enables both `nodejs_compat` and `nodejs_compat_v2` by default. These flags are not used for these compatibility dates. Existing projects do not need to remove them when updating their compatibility date. For earlier dates, add `nodejs_compat` to your [Wrangler configuration file](https://fix-ai-gateway-guardrails-streaming-docs.previews.developers.cloudflare.com/workers/wrangler/configuration/) to opt in. For instructions to turn off Node.js compatibility, refer to the [Node.js compatibility flag](https://fix-ai-gateway-guardrails-streaming-docs.previews.developers.cloudflare.com/workers/configuration/compatibility-flags/#nodejs-compatibility-flag).

## `MockTracker`

The `MockTracker` API in Node.js provides a means of tracking and managing mock objects in a test environment.

```js
import { mock } from 'node:test';

const fn = mock.fn();
fn(1,2,3);  // does nothing... but

console.log(fn.mock.callCount());  // Records how many times it was called
console.log(fn.mock.calls[0].arguments);  // Records the arguments that were passed each call
```

The full `MockTracker` API is documented in the [Node.js documentation for MockTracker ↗](https://nodejs.org/docs/latest/api/test.html#class-mocktracker).

The Workers implementation of `MockTracker` currently does not include an implementation of the [Node.js mock timers API ↗](https://nodejs.org/docs/latest/api/test.html#class-mocktimers).

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