Prefer Fakes over Mocks
tyrrrz.me
Prefer Fakes over Mocks
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Re: Prefer Fakes over Mocks
#2Not particularly convincing. Mocks work well because you can quickly define them in a given unit test and forget about it.
I can see fakes being useful in certain cases, but only just in certain cases.
Could be my inexperience with C#, but it didn't do justice describing the point in code samples.
Re: Prefer Fakes over Mocks
#3[deleted]
Re: Prefer Fakes over Mocks
#4Not particularly convincing. Mocks work well because you can quickly define them in a given unit test and forget about it. I can see fakes being useful in certain cases, but only just in certain cases. Could be my inexperience with C#, but it didn't do justice describing the point in code samples.
I question a lot of advice like this, and agree with you. I’d generally far rather use NSubstitute than have to write fake classes, but I can see the utility in some cases.
My honest response is this: Writing tests should be quick and painless. Maintaining fakes is more painful than maintaining substitutes. Substitutes let me interrogate side effects in great detail. I’m not concerned will performance in unit tests. Ergo, substitutes are quicker and less painful, so IMO that’s a win.
But for real though, why should anyone care about someone else’s test architecture, of all things. As long as you neither under- or over-testing, why on earth does it matter?
Re: Prefer Fakes over Mocks
#5Not particularly convincing. Mocks work well because you can quickly define them in a given unit test and forget about it. I can see fakes being useful in certain cases, but only just in certain cases. Could be my inexperience with C#, but it didn't do justice describing the point in code samples.
I tried to distill down the basics a few years ago in a 1 page article: https://testing.googleblog.com/2013/06/testing-on-toilet-fak...
The example is a little contrived, but the whole article fits on one sheet of paper and does yield a better test than mocks would.
Testing against the real system is always better than testing against a fake. That should be your first preference, and if you can modify the system to make testing against it easier, that's even better. Sometimes you can't, and if your interaction is complicated and the parts that you care about are simple, a fake can get you good confidence that your part works. Mocks just feel like writing the code again -- in your code, you write "call a function with an argument, then call another function with an argument" and in the tests you write "pass if a function is called with an argument, and again with an argument". It can be the right thing at the right time, but it's usually writing a test to make some automated linter shut up. And that's a complete waste of time.
Re: Prefer Fakes over Mocks
#6How are fakes, as described in this article, not also implementation-aware testing?
Re: Prefer Fakes over Mocks
#7Not particularly convincing. Mocks work well because you can quickly define them in a given unit test and forget about it. I can see fakes being useful in certain cases, but only just in certain cases. Could be my inexperience with C#, but it didn't do justice describing the point in code samples.
I question a lot of advice like this, and agree with you. I’d generally far rather use NSubstitute than have to write fake classes, but I can see the utility in some cases. My honest response is this: Writing tests should be quick and painless. Maintaining fakes is more painful than maintaining substitutes. Substitutes let me interrogate side effects in great detail. I’m not concerned will performance in unit tests.…
> why should anyone care about someone else’s test architecture, of all things. As long as you neither under- or over-testing, why on earth does it matter?
If you have to maintain tests written by other devs you might start to care. Devs apply different patterns to writing tests and show different amounts of discipline doing so. Some produce lots of duplication ("it doesn't matter, it's just a unit test"), others prefer a complete setup and tear-down before and after every little assertion. I've seen things..
Re: Prefer Fakes over Mocks
#8[deleted]
Re: Prefer Fakes over Mocks
#9Not particularly convincing. Mocks work well because you can quickly define them in a given unit test and forget about it. I can see fakes being useful in certain cases, but only just in certain cases. Could be my inexperience with C#, but it didn't do justice describing the point in code samples.
I question a lot of advice like this, and agree with you. I’d generally far rather use NSubstitute than have to write fake classes, but I can see the utility in some cases. My honest response is this: Writing tests should be quick and painless. Maintaining fakes is more painful than maintaining substitutes. Substitutes let me interrogate side effects in great detail. I’m not concerned will performance in unit tests.…
[deleted]
Re: Prefer Fakes over Mocks
#10Fakes are great for objects that store data. Like in this example.
If I use Entity Framework Core I also love the in-memory provider (or SQLite in-memory), which gives you a very well faked database context for unit tests.
In some cases you can create end to end tests, that run and verify the complete business logic, without hitting the database at all. A mixture between unit and integration tests.
https://docs.microsoft.com/en-us/ef/core/miscellaneous/testi...