Discussion on "Unit Tests Done Right"

Aleksei Zagoskin · 2022-05-01T20:47:19.731Z

UPDATE: The second part is now available: How to test LINQ and mappings. There are countless articles on the web about unit tests: TDD approach, beginner's guides, mocking frameworks, test coverage tools and more. However, the vast majority of these ...

What tool you are using to check test coverage? You've shared a screenshot with us but not its name :)

Ah, it's Rider, it offers this stuff out of the box. I believe Resharper has it as well.

When you check an exception message do you think it might be worth using a constant template for the error message to don't break a test just because you have changed the message, or better to have the test broken on each change of the message and amend it accordingly?

Good call. Sometimes I don't check the exception message at all, just exception type and properties (for custom exceptions).

Test Strategy for Example 2 maybe should contain checking that we don't change any other user's entity field but only password. But this could mess up the test. What do you think? What is your assessing path to decide whether include or not anything to test?

We may consider these things for testing:

Happy path e.g. return value is correct / expected exception gets thrown / messages get published etc.
All if-else-switch branches.
Edge cases such as awkward input parameters (int.MaxValue/MinValue/0, long strings, nulls, empty strings etc).
The order of method calls (e.g. validation goes before we save data to the database).

I know it is out of the scope of the topic but I'd like to know your opinion, what is the strategy of using cancellation tokens in your examples. I guess the UserManager is invoked by an action (as part of a controller) and then from UserManager you call a repo and pass ct to it. Inside repo you pass ct to linq async operation. What is the benefit to do that? What is the source of the ct? Who and why might cancel the token in the presented chain of calls?

Good point! Your assumption is absolutely correct, cancellation tokens come from controllers and do the cancellation, for instance, if/when a connection between the client and the server is interrupted. In these cases we may want to cancel "get" queries while let others finish.

Alexey Zagoskin yes, agree, it is good to cancel a token when/if a connection is interrupted, but I've never used this before. Could you please refer to a web page or example about that, I mean how to detect the interruption and react.

Hi Alexey, thank you a lot for the knowledge sharing and insides, it is very interesting, keep going!

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