Structuring Unit Test Code

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UPDATE: I’ve since supplemented this with another approach.

Jeremy Miller asks the question, “How do you organize your NUnit test code?”.  My answer? I don’t, I organize my MbUnit test code.

Bad jokes aside, I do understand that his question is more focused on the structure of unit testing code and not the structure of any particular unit testing framework.

I pretty much follow the same structure that Jeremy does in that I have a test fixture per class (sometimes more than one per class for special cases).  I experimented with having a test fixture per method, but gave up on that as it became a maintenance headache.  Too many files!

One convention I use is to prefix my unit test projects with “UnitTest”.  Thus the unit tests for Subtext are in the project UnitTests.Subtext.dll.  The main reason for this, besides the obvious fact that it’s a sensible name for a project that contains unit tests, is that for most projects, the unit test assembly would show up on bottom in the Solution Explorer because of alphabetic ordering.

So then I co-found a company whose name starts with the letter V.  Doh!

UPDATE: I neglected to point out (as David Hayden did) that with VS.NET 2005 I can use Solution Folders to group tests. We actually use Solution Folders within Subtext. Unfortunately, many of my company work is still using VS.NET 2003, which does not boast such a nice feature.

One thing I don’t do is separate my unit tests and integration tests into two separate assemblies.  Currently I don’t separate those tests at all, though I have plans to start. 

Even when I do start separating tests, one issue with having unit tests in two separate assemblies is that I don’t know how to produce NCover reports that merge the results of coverage from two separate assemblies.

One solution I proposed in the comments to Jeremy’s post is to use a single assembly for tests, but have UnitTests and Integration Tests live in two separate top level namespaces.  Thus in MbUnit or in TD.NET, you can simply run the tests for one namespace or another.

Example Namespaces: Tests.Unit and Tests.Integration

In the root of a unit test project, I tend to have a few helper classes such as UnitTestHelper, which contains static methods useful for unit tests. I also have a ReflectionHelper class, just in case I need to “cheat” a little. Any other classes I might find useful typically go in the root, such as my SimulatedHttpRequest class as well.

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