#Scoped cleanup

Rstest supports scoped cleanup for temporary test changes. When your runtime or toolchain supports explicit resource management, you can use using to automatically restore resources at the end of a block.

This is useful when a test temporarily changes shared state, such as spies, environment variables, globals, or fake timers.

#Disposable using syntax

rs.stubEnv(), rs.stubGlobal(), and rs.useFakeTimers() return disposable resources that work with using.

#Spy cleanup

Mocks and spies implement Symbol.dispose, so a spy created with rs.spyOn() is restored when the using block exits.

import { expect, rs, test } from '@rstest/core';

test('logs a warning', () => {
  {
    using warn = rs.spyOn(console, 'warn').mockImplementation(() => undefined);

    console.warn('invalid payload');
    expect(warn).toHaveBeenCalledWith('invalid payload');
  }

  // console.warn is restored here
});

See Mock for more spy examples.

#Environment variables

rs.stubEnv() returns a disposable resource. When it leaves a using scope, only that scoped env stub is restored.

import { expect, rs, test } from '@rstest/core';

test('uses test env', () => {
  {
    using _env = rs.stubEnv('NODE_ENV', 'test');

    expect(process.env.NODE_ENV).toBe('test');
  }

  // NODE_ENV is restored here
});

Nested env stubs are restored in reverse order:

using _outer = rs.stubEnv('FEATURE_FLAG', 'on');
expect(process.env.FEATURE_FLAG).toBe('on');

{
  using _inner = rs.stubEnv('FEATURE_FLAG', 'off');
  expect(process.env.FEATURE_FLAG).toBe('off');
}

expect(process.env.FEATURE_FLAG).toBe('on');

You can still call rs.unstubAllEnvs() to restore all env stubs in the current test.

#Globals

rs.stubGlobal() also returns a disposable resource. This is convenient for temporarily replacing global APIs.

import { expect, rs, test } from '@rstest/core';

test('uses a global feature flag', () => {
  {
    using _global = rs.stubGlobal('__FEATURE_ENABLED__', true);

    expect(globalThis.__FEATURE_ENABLED__).toBe(true);
  }

  // __FEATURE_ENABLED__ is restored here
});

You can still call rs.unstubAllGlobals() to restore all global stubs in the current test.

#Fake timers

rs.useFakeTimers() returns a disposable resource that restores real timers when the block exits.

import { expect, rs, test } from '@rstest/core';

test('runs delayed work', () => {
  {
    using _timers = rs.useFakeTimers();

    const fn = rs.fn();
    setTimeout(fn, 1000);

    rs.advanceTimersByTime(1000);
    expect(fn).toHaveBeenCalledTimes(1);
  }

  expect(rs.isFakeTimers()).toBe(false);
});

#Async resources

For asynchronous resources that implement Symbol.asyncDispose, use await using. Rstest's browser provider resources support async disposal internally so provider pages, contexts, and browsers can be closed by the same explicit resource management protocol.

await using resource = createAsyncResource();

await resource.run();
// resource[Symbol.asyncDispose]() is awaited here

Use using for synchronous cleanup and await using when cleanup needs to await asynchronous work.