Our getAuthToken() function depends on the response returned from the server quite singificantly. For starters, there's a validation layer to handle error responses:

if (response.status === 401) {
  throw new Error('Authentication failed: invalid credentials')
}

if (!response.ok) {
  throw new Error('Authentication failed: network error')
}

Then, there's a successful, "happy path" scenario handling, where we read the response body as JSON and return the token property from the response body:

const json = await response.json()

return {
  token: json.token,
}

And we need to test all of those scenarios!

But let's start from the beginning. Let's start from the happy path.

If the server returns a 200 response, our function will read its body and return some of its properties. That's a great intention to put into test.

For that intention to happen, the POST https://api.example.com/auth request must be (1) intercepted; and (2) mocked. Wait, those two steps are precisely what request handlers are for!

👨‍💼 In this exercise, create a new request handler in handlers.ts for the request made by the getAuthToken() function. Respond to that request with a mocked JSON response containing { token: 'abc-123' } in its body. And, finally, finish the test at to validate the getAuthToken() function returning the right token from the received response. Verify your solution by running npm test.