使用Google Test测试文件输出？

Question

I'm working on a project to create a simulator (for modeling biological systems) in C++. The simulator takes an input file of parameters and then generates an output file with hundreds of molecule counts at different time points from the simulation. I'm using Google Test for all of my unit testing. I also want to include some higher level tests where I supply an input file with various model parameters and then check that the output file matches some reference file. Someone recommended using bash-tap for these higher level tests, but I'd prefer to stick to Google Test if possible. Is it possible to use Google Test for the higher level tests that I've described here?

Answer 1

We write CAE software (simulators) and use Google Test. We face similar issues, so hopefully you'll find the answers practical.

You can write the higher-level tests, but you will often have to do more than just "EXPECT_EQ()" for checking pass/fail. For example, if you had to test the connectivity of two abitrary graphs, it can be difficult if the algorithms are allowed to vary the order of nodes. Or, if you are comparing a matrix, sometimes you can have cases where the matrix rows and columns can be switched with no problem. Perhaps round-off error is ok. Be prepared to deal with these types of problems as they will be much more of an issue with a full simulator than with a unit test.

A more practical issue is when your organization says "run all tests before you check in." Or, maybe they run every time you hit the build button. If that's the case, you need to differentiate these unit tests from the higher level tests. We use Google Test Runner in Visual Studio, and it expects to run everything where the filename is "*Test*". It is best to name the higher level tests something else to be clear.

We also had to turn our entire executable into a DLL so that it could have tests run on top of it. There are other approaches (like scripting) which could be used with Google Test, but we've found the executable-as-a-dll approach to work. Our "real" product executable is simply a main() function that calls app_main() in the dll.

And, one final tip when using the Runner: If your app gets the --gtest_list_tests argument, don't do a bunch of expensive setup:

// Don't run if we are just listing tests.
if (!::testing::GTEST_FLAG(list_tests))
{
        // Do expensive setup stuff here.
}

int result = RUN_ALL_TESTS();

if (!::testing::GTEST_FLAG(list_tests))
{
        // Do expensive shutdown stuff here.
}