Join us and get access to thousands of tutorials and a community of expert Pythonistas.

Unlock This Lesson

This lesson is for members only. Join us and get access to thousands of tutorials and a community of expert Pythonistas.

Unlock This Lesson

Hint: You can adjust the default video playback speed in your account settings.
Hint: You can set your subtitle preferences in your account settings.
Sorry! Looks like there’s an issue with video playback 🙁 This might be due to a temporary outage or because of a configuration issue with your browser. Please refer to our video player troubleshooting guide for assistance.

Side Effects as an Iterable (Part 1)

Lee Gaines
Improve Your Tests With the Python Mock Object Library Lee Gaines 02:33
Recommended Tutorial Course Slides (.pdf) Sample Code (.zip) Ask a Question

00:00 Okay. So before moving away from side effects, let’s look at one more feature that I think is really cool. And that is using .side_effect as an iterable.

00:10 Let’s say that when we make a request to our API—

00:16 our get_holidays() API—it times out on the first time, and then it responds successfully on the second time.

00:25 The way we can do that is to say the .side_effect of request.get()—remember, this is defined in our get_holidays() function—the .side_effect will first be a Timeout.

00:38 We have this Timeout exception imported. So we can set the .side_effect as not just this callable, but a list, and the first side effect is a Timeout and then the second one is a call to our .log_request() function, which mocks a successful response.

01:03 And then in our test, we can say with self.assertRaises(Timeout): we will call get_holidays(). So again, this is saying that when we call get_holidays(), we expect it to raise a Timeout exception.

01:24 This is going to be the first side effect. And then after that, our second side effect is the call to our function, which returns a response successfully, so this test should pass.

01:39 And then we can verify that we’re actually calling requests.get() twice. So, the first time is with the Timeout, the second time is a successful response.

01:50 We can say assert requests.get.—and remember, this is a Mock object, so we have this attribute called .call_count, and that should be 2. Let’s save that and we will open up a terminal. Whoops, I had a typo here—requests. We’ll save that, open up a terminal, let’s clear the screen, and we’re going to run our test cases again.

02:20 Okay. So we have an error. That looks like line 24, in get_holidays […] 'function' object has no attribute 'status_code'.

Become a Member to join the conversation.