Ancestors

Written by Pamela Fox on 2024-12-06 at 23:02

I had a lot of tricky tests to write today that needed mocks against an async SDK.

To get started, I tried out GitHub Copilot "generate tests".

Observations:

• Copilot really liked using MagicMock, whereas I generally construct the actual class and use monkeypatch.setattr to mock the methods used.
• Copilot's tests did often pass, after a few tweaks.
• When a test didn't pass, I found it harder to debug MagicMock mocks, because they mocked too much- I wasn't getting errors for undefined attrs.

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Written by Pamela Fox on 2024-12-06 at 23:03

So I eventually modified most tests to "my style" with monkeypatch.setattr whenever possible.

I'm still grateful for Copilot's help since:

1. I've now learnt more about how to use MagicMock, for when I need it

2. sometimes it's less intimidating to edit an existing failed test than to write a brand new one

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Written by Pamela Fox on 2024-12-06 at 23:03

I'm curious what style mocks y'all prefer! should i be magic mocking more??

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Toot

Written by jonny (good kind) on 2024-12-06 at 23:09

@pamelafox

I definitely prefer custom mocks in most cases - magic mocks work when everything is totally unit-ized and so you want to assume nothing about the components surrounding the thing to be tested, but in practice, if you can't actually use the thing in testing, it's good to have at least some imitation of its real behavior, because otherwise you're usually testing nothing

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Descendants

Written by jonny (good kind) on 2024-12-06 at 23:11

@pamelafox

I mean I assume you know more than me, but since you asked!

Also im not saying to not magic mock, it's just for a different situation than the ones I usually run into where I need a mock. More a "when I write tests I usually write the mocks" than a "dont use magicmock"

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Written by Pamela Fox on 2024-12-06 at 23:18

@jonny Okay yeah that makes sense. I think I prefer tests that aren't as clean in terms of "unit-ization" since that gives me additional opportunities to discover issues? Also better type hinting in my tests, since you cant get type hints from Magic mocks. Thanks for sharing your take!

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