Jest done callback is not assignable to parameter of type ProvidesCallback or undefined

Question

I am trying to create a test with jest and I want to use done() callback but Typescript is not accepting it, I tried to use type any, jest.DoneCallback or leaving it without any type but again is not working. Any solution or idea?

it('implements optimistic concurrency control', async (done: any) => {
  const ticket = Ticket.build({
    title: 'Concert 123423',
    price: 5,
    userId: '123'
  });
  await ticket.save();
  
  const firstInstance = await Ticket.findById(ticket.id);
  const secondInstance = await Ticket.findById(ticket.id);

  firstInstance!.set({ price: 10 });
  secondInstance!.set({ price: 15 });

  await firstInstance!.save();

  try {
    await secondInstance!.save();
  } catch (err) {
    console.log(err);
    return done();
  }
  throw new Error('Should not reach this point');
});

Answer 1

You choose either to use Promise or a callback. In your case, you want to use async/await because you are waiting for the save() methods before continuing in the flow.

Your code updated:

it('implements optimistic concurrency control', async () => {
  const ticket = Ticket.build({
    title: 'Concert 123423',
    price: 5,
    userId: '123'
  });
  await ticket.save();
  
  const firstInstance = await Ticket.findById(ticket.id);
  const secondInstance = await Ticket.findById(ticket.id);

  firstInstance!.set({ price: 10 });
  secondInstance!.set({ price: 15 });

  await firstInstance!.save();

  try {
    await secondInstance!.save();
  } catch (err) {
    console.log(err);
    return;
  }
  throw new Error('Should not reach this point');
});

Here is an example of using the callback:

it('some asynchronous test', (done) => {
  request(app)
    .get('/endpoint')
    .expect(200)
    .expect((res) => {
       // insert some code stuff here
    })
    // The callback function is passed in so it will call
    // it once it finishes the asynchronous code
    .end(done)
})

Also, you shouldn't have to specify the type for the callback, it should be inferred. You can if you want though.