Build Your Own Test Framework: A Practical Guide to Writing Better Automated Tests

© The Author(s), under exclusive license to APress Media, LLC, part of Springer Nature 2023

D. IrvineBuild Your Own Test Frameworkhttps://doi.org/10.1007/978-1-4842-9247-1_9

9. Supporting Asynchronous Tests

Daniel Irvine¹  

(1)

London, UK

 

Sometimes we want to test async stuff:

it("does something async", async () => {

  await something();

  expect(thing).toBe("foo");

});

For this to work, notice that the second argument to the it function call is now marked as async. This is a hint to how the test runner must change: it must assume that the test body returns a Promise object, which is what the async method means.

But with our current test runner, our tests will complete, reporting no failures for any test that awaits a Promise, because our test runner won’t ...