How should internal classes and methods be tested?

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testing an internal class

I like to have my test classes in a separate assembly, and that is causing some problem with testing internal classes. Since internal classes and methods are only visible inside of the assembly my test assembly can't see those classes and methods. What is the most effective way to test those classes? Do I need to use reflection to access the methods I wan't to test?

This has been asked before: http://stackoverflow.com/questions/606137/testing-an-internal-class — Gerrie Schenck, Nov 16 '10 at 07:53
Indeed, and it also has the answer there. Test your top-level API, not your internal classes. If you must, you can use the InternalsVisibleTo however. — Peter, Nov 16 '10 at 07:55
Sorry for that... is it possible to mark the question as duplicate? — Tomas Jansson, Nov 16 '10 at 08:22

score 6 · Answer 1 · edited May 23 '17 at 12:19

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You can use the InternalsVisbleTo attribute.

See this question: How do I allow assembly (unit testing one) to access internal properties of another assembly?

edited May 23 '17 at 12:19

Community

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answered Nov 16 '10 at 07:53

Razzie

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Of course you can do that, but it feels weird to me. – Tomas Jansson Nov 16 '10 at 08:23

score 1 · Answer 2 · answered Nov 16 '10 at 07:57

My preferred option is to just test them indirectly via the public classes and methods that use them, just like with private classes and methods.

Depends though, I tend to do TDD, and end up hardly ever using internal. I don't really like the idea of putting an attribute in production code just to make it testable.

score 1 · Answer 3 · answered Nov 16 '10 at 08:39

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You could refactor the functionality into new class with a public method and then test that method.

answered Nov 16 '10 at 08:39

Gregor Slavec

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score 0 · Answer 4 · answered Nov 16 '10 at 16:23

I think you may question where is your internal class is used and for what purpose.

If it is there it must have its own mission. And that mission might be effecting something; for instance another object's state.

So by testing that 'another' object you might have a chance to test your internal class indirectly.

But the good start can be questioning if it is really necessary to have that internal class. If your intention is to write a TTDD (Testable Test Driven Development) your design might require another architecture.

How should internal classes and methods be tested?

4 Answers4