How to use jest.each asynchronously

Question

I am having problems loading filenames into jest.each asynchronously.

My code:

let files: string[][]

function getFilesWorking() {
  files = [["test1"], ["test2"]]
}

async function getFilesAsync() {
  files = await Promise.resolve([["test1"], ["test2"]])
}

beforeAll(() => {
  console.log("before")
})

describe.only("Name of the group", () => {
  getFilesAsync()
  test.each(files)("runs", f => {})
})

beforeAll is executed before each test but NOT before initialization of test.each, so I end up with undefined.

How can I load files before using test.each?

Answer 1

As of Jest 28.1.3 and prior, this is not possible. There is an open issue documenting this behavior.

The best thing you can do for now is put your tests in a regular it() test and do a deep value comparison:

it('tests an array of cases', async () => {
  const data = await getSomeAsyncData()
  const expectedData = [ ... ]

  expect(data).toEqual(expectedData)
})