How do you run your unit tests? Compiler flags? St

Question

I'm just getting started with TDD and am curious as to what approaches others take to run their tests. For reference, I am using the google testing framework, but I believe the question is applicable to most other testing frameworks and to languages other than C/C++.

My general approach so far has been to do one of three things:

1. Write the majority of the application in a static library, then create two executables. One executable is the application itself, while the other is the test runner with all of the tests. Both link to the static library.

2. Embed the testing code directly into the application itself, and enable or disable the testing code using compiler flags. This is probably the best approach I've used so far, but clutters up the code a bit.

3. Embed the testing code directly into the application itself, and, given certain command-line switches either run the application itself or run the tests embedded in the application.

None of these solutions are particularly elegant...

How do you do it?

Answer 1

I use two approaches, for dlls I just link my unit tests with the dll, easy. For executables I include the source files that are being tested in both the executable project and the unit test project. This adds slightly to the build time but means I don't need to separate the executable in to a static lib and a main function.

I use boost.test for unit testing and cmake to generate my project files and I find this the easiest approach. Also I am slowly introducing unit-testing to a large legacy code base so I am trying to introduce the least amount of changes, in case I inconvenience other developers and discourage them from unit testing. I would worry that using a static library just for unit testing might be seen as an excuse not adopt it.

Having said this, I think the static library approach is a nice one especially if you are starting from scratch.

Answer 2

I go with #1, some reasons are

• It allows to check that each lib links correctly
• You don't want extra code in the product
• It's easier to debug individual small test programs
• You may need multiple executables for some tests (like communication tests)

For C++ build and test, I like to use CMake which can run a selection of the target executables as tests and print a summary of the results.

Answer 3

Personnally, I use another approach that relies a bit on yours:

I keep the project-to-test intact. If it's an executable, it should stay an executable. You simply create a post build action in order to aggregate all obj files into a static library.

Then, you can create you test project, linking the test framework and your previously generated static library.

Here are some topics corresponding to your question:

• Visual Studio C++: Unit test exe project with google test?
• Linker error - linking two "application" type projects in order to use Google Test

Answer 4

For C/C++ apps I try to have as much code as possible in one or more dlls, with the main application being the bare minimum to start-up and hand-off to the dll. Dlls are much easier to test because they can export as many entry points as I like for a test application to use.

I use a seperate test application that links to the Dll(s). I'm strongly in favour of keeping test code and "product" code in seperate modules.

Answer 5

I'm using a third-party test-runners with their framework and including testing in build script. Tests are outside of production code (external dll).

Answer 6

Your approach no. 1 is the way I've always done it in C/C++ and Java. Most of the application code is in the static library and I try to keep the amount of extra code needed for the application to a minimum.

The way I approach TDD in Python and other dynamic languages is slightly different in that I leave the source code for the application and tests lying around and a test runner finds the tests and runs them.