We have several situations in our tests where we want the return value of a function and use .toBe(...) to compare it with the desired outcome. There is no problem with synchronous functions to be handled this way. But there might be a problem with asynchronous functions, as they require an additional step, where we do not compare the result of the function itself but chain the expect.toBe into the .then part of the test. e.g.

test('the data is peanut butter', () => {
  expect.assertions(1);
  return fetchData().then(data => {
    expect(data).toBe('peanut butter');
  });
});

Or wait for the state to update with waitForState(). Otherwise we will pass tests even though they should be failing: