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Q: How can I wait for all my dynamic modules to be finished before my assertions in Jest ?

Scenario:

// normal code
export default {
  a() {
     import('b', () => {
        window.hello = 'there'
     })
  }
}

// test
import normalCode from 'normalCode'
it('should add to window', () => {
  normalCode.a()
  expect(window.hello).toBe('there')
})

The execution of the code above is:

runs normalCode.a()
runs expect(window.hello).toBe('there')
import finished and is running window.hello = 'there'
it fails because assertions were wrong at step 2, but they would pass after step 3.

about 4 years ago · Juan Pablo Isaza

Answer question

Answer 1 · 2022-07-01T01:14:38.165Z

I believe you'll want to return the import promise from function a.

// normal code
export default {
  a() {
     return import('b', () => {
        window.hello = 'there'
     })
  }
}

Then await it in your test.

// test
import normalCode from 'normalCode'
it('should add to window', async () => {
  await normalCode.a()
  expect(window.hello).toBe('there')
})