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.

Answer 3

In Java you should use Junit4, either by itself or (I think better) with an IDE. We have used three environments : Eclipse, NetBeans and Maven (with and without IDE). There can be some slight incompatibilities between these if not deployed systematically.

Generally all tests are in the same project but under a different directory/folder. Thus a class:

org.foo.Bar.java

would have a test

org.foo.BarTest.java

These are in the same package (org.foo) but would be organized in directories:

src/main/java/org/foo/Bar.java 

and

src/test/java/org/foo/BarTest.java 

These directories are universally recognised by Eclipse, NetBeans and Maven. Maven is the pickiest, whereas Eclipse does not always enforce strictness.

You should probably avoid calling other classes TestPlugh or XyzzyTest as some (old) tools will pick these up as containing tests even if they don't.

Even if you only have one test for your method (and most test authorities would expect more to exercise edge cases) you should arrange this type of structure.

EDIT Note that Maven is able to create distributions without tests even if they are in the same package. By default Maven also requires all tests to pass before the project can be deployed.

Answer 4

Most setups I have seen or use have a separate project that has the tests in them. This makes it a lot easier and cleaner to work with. As a separate project it's easy to deploy your code without having to worry about the tests being a part of the live system.

As testing progresses, I have seen separate projects for unit tests, integration tests and regression tests. One of the main ideas for this is to keep your unit tests running as fast as possible. Integration & regression tests tend to take longer due to the nature of their tests (connecting to databases, etc...)

Answer 5

I typically create a parallel package structure in a distinct source tree in the same project. That way your tests have access to public, protected and even package-private members of the class under test, which is often useful to have.

For example, I might have

myproject
    src
        main
            com.acme.myapp.model
                User
            com.acme.myapp.web
                RegisterController
        test
            com.acme.myapp.model
                UserTest
            com.acme.myapp.web
                RegisterControllerTest

Maven does this, but the approach isn't particularly tied to Maven.

Answer 6

This would depend on the Testing Framework that you are using. JUnit, NUnit, some other? Each one will document some way to organize the test code. Also, if you are using continuous integration then that would also affect where and how you place your test. For example, this article discusses some options.

Answer 7

Create a new project in the same solution as your code.

If you're working with c# then Visual Studio will do this for you if you select Test > New Test... It has a wizard which will guide you through the process.

Answer 8

hmm. you want to test random number generator... may be it will be better to create strong mathematical proof of correctness of algorithm. Because otherwise, you must be sure that every sequence ever generated has a desired distribution

Answer 9

In the case of C# and Visual Studio 2010, you can create a test project from the templates which will be included in your project's solution. Then, you will be able to specify which tests to fire during the building of your project. All tests will live in a separate assembly.

Otherwise, you can use the NUnit Assembly , import it to your solution and start creating methods for all the object you need to test. For bigger projects, I prefer to locate these tests inside a separate assembly.

You can generate your own tests but I would strongly recommend using an existing framework.

Answer 10

Create separate projects for unit-tests, integration-tests and functional-tests. Even if your "real" code has multiple projects, you can probably do with one project for each test-type, but it is important to distinguish between each type of test.

For the unit-tests, you should create a parallel namespace-hierarchy. So if you have crazy.juggler.drummer.Customer, you should unit-test it in crazy.juggler.drummer.CustomerTest. That way it is easy to see which classes are properly tested.

Functional- and integration-tests may be harder to place, but usually you can find a proper place. Tests of the database-layer probably belong somewhere like my.app.database.DatabaseIntegrationTest. Functional-tests might warrant their own namespace: my.app.functionaltests.CustomerCreationWorkflowTest.

But tip #1: be tough about separating the various kind of tests. Especially be sure to keep the collection of unit-tests separate from the integration-tests.