where should I put my test code for my class?

Question

So I've written a class and I have the code to test it, but where should I put that code? I could make a static method Test() for the class, but that doesn't need to be there during production and clutters up the class declaration. A bit of searching told me to put the test code in a separate project, but what exactly would the format of that project be? One static class with a method for each of the classes, so if my class was called Randomizer, the method would be called testRandomizer?

What are some best practices regarding organizing test code?

EDIT: I originally tagged the question with a variety of languages to which I thought it was relevant, but it seems like the overall answer to the question may be "use a testing framework", which is language specific. :D

Answer 1

Whether you are using a test framework (I highly recommend doing so) or not, the best place for the unit tests is in a separate assembly (C/C++/C#) or package (Java).

You will only have access to public and protected classes and methods, however unit testing usually only tests public APIs.

I recommend you add a separate test project/assembly/package for each existing project/assembly/package.

The format of the project depends on the test framework - for a .NET test project, use VSs built in test project template or NUnit in your version of VS doesn't support unit testing, for Java use JUnit, for C/C++ perhaps CppUnit (I haven't tried this one).

Test projects usually contain one static class init methods, one static class tear down method, one non-static init method for all tests, one non-static tear down method for all tests and one non-static method per test + any other methods you add.

The static methods let you copy dlls, set up the test environment and clear up the test enviroment, the non-static shared methods are for reducing duplicate code and the actual test methods for preparing the test-specific input, expected output and comparing them.

Answer 2

Where you put your test code depends on what you intend to do with the code. If it's a stand-alone class that, for example, you intend to make available to others for download and use, then the test code should be a project within the solution. The test code would, in addition to providing verification that the class was doing what you wanted it to do, provide an example for users of your class, so it should be well-documented and extremely clear.

If, on the other hand, your class is part of a library or DLL, and is intended to work only within the ecosystem of that library or DLL, then there should be a test program or framework that exercises the DLL as an entity. Code coverage tools will demonstrate that the test code is actually exercising the code. In my experience, these test programs are, like the single class program, built as a project within the solution that builds the DLL or library.

Note that in both of the above cases, the test project is not built as part of the standard build process. You have to build it specifically.

Finally, if your class is to be part of a larger project, your test code should become a part of whatever framework or process flow has been defined for your greater team. On my current project, for example, developer unit tests are maintained in a separate source control tree that has a structure parallel to that of the shipping code. Unit tests are required to pass code review by both the development and test team. During the build process (every other day right now), we build the shipping code, then the unit tests, then the QA test code set. Unit tests are run before the QA code and all must pass. This is pretty much a smoke test to make sure that we haven't broken the lowest level of functionality. Unit tests are required to generate a failure report and exit with a negative status code. Our processes are probably more formal than many, though.