Lint for setting advanceTimers with user-event when using jest.useFakeTimers

[backwardok]

Name for new rule

advance-timers-with-fake-timers

Description of the new rule

Enforce using the advanceTimers option for user-event when using jest's useFakeTimers in order to prevent testing timeouts

Testing Library feature

user-event's advanceTimers option when using fake timers

Testing Library framework(s)

user-event (across any Testing Library framework that can use it)

What category of rule is this?

Warns about a potential error

Optional: other category of rule

No response

Code examples

Using fake timers within a test directly:

jest.useFakeTimers();
const user = userEvent.setup(); // Warn - advanceTimers not set

beforeEach(() => {
  jest.useFakeTimers()
});

test('some behavior with user action', async () => {
  const user = userEvent.setup(); // Warn - advanceTimers not set
  // Test behavior
})

Anything else?

No response

Do you want to submit a pull request to make the new rule?

No

[Belco90]

Hi @backwardok. Thanks for your suggestion, sounds like an interesting rule!

[alexeyr-ci2]

Should it also warn when using userEvent.click(...) and similar methods directly without userEvent.setup()?

[Belco90]

Should it also warn when using userEvent.click(...) and similar methods directly without userEvent.setup()?

The Testing Library docs only reference passing the advanceTimers to the setup method, so I don't think other similar methods should be reported.

[alexeyr-ci2]

The docs say

userEvent.click() (which will trigger setup internally)

I thought it calls userEvent.setup() and so is equivalent to the code this rule would warn about. I guess

1. the documentation doesn't say so explicitly
2. this is discouraged anyway and it may be better to have a different rule banning it.