Shared utils functions for testing with Jest

Question

I have some utils functions that I\'m using among various Jest tests, for example a function like this, for mocking a fetch response:

Answer 1

Another approach is by having a test directory and moving helpers on it.

src/
  components/
  utils/
  ...
test/
  testHelpers.js

Then on the test:

// src/components/MyComponent.spec.js
import { helperFn } from '../../test/testHelpers';

Benefits:

• Be explicit of where the function is coming from
• Separate helpers that need to be tested from those that do not ¹

Drawbacks:

• The test directory might look silly by containing just a helper file
• AFAIK this approach is no where specified on official documentation

Looks like GitLab is implementing this approach on their RoR project.

¹ no matter which approach you take, please don't test the test helpers. If the helper fails then your test must fail too. Otherwise your helper is not helping at all.