What unit-testing framework should I use for Qt? [closed]

Question

I am just starting up a new project that needs some cross-platform GUI, and we have chosen Qt as the GUI-framework.

We need a unit-testing framework, too. Until about a year ago we used an in-house developed unit-testing framework for C++-projects, but we are now transitioning to using Google Test for new projects.

Does anyone have any experience with using Google Test for Qt-applications? Is QtTest/QTestLib a better alternative?

I am still not sure how much we want to use Qt in the non-GUI parts of the project - we would probably prefer to just use STL/Boost in the core-code with a small interface to the Qt-based GUI.

EDIT: It looks like many are leaning towards QtTest. Is there anybody who has any experience with integrating this with a continous integration server? Also, it would seem to me that having to handle a separate application for each new test case would cause a lot of friction. Is there any good way to solve that? Does Qt Creator have a good way of handling such test cases or would you need to have a project per test case?

Answer 1

You don't have to create separate tests applications. Just use qExec in an independent main() function similar to this one:

int main(int argc, char *argv[])
{
    TestClass1 test1;
    QTest::qExec(&test1, argc, argv);

    TestClass2 test2;
    QTest::qExec(&test2, argc, argv);

    // ...

    return 0;
}

This will execute all test methods in each class in one batch.

Your testclass .h files would look as follows:

class TestClass1 : public QObject
{
Q_OBJECT

private slots:
    void testMethod1();
    // ...
}

Unfortunately this setup isn't really described well in the Qt documentation even though it would seem to be quite useful for a lot of people.

Answer 2

I started off using QtTest for my app and very, very quickly started running into limitations with it. The two main problems were:

1) My tests run very fast - sufficiently quickly that the overhead of loading an executable, setting up a Q(Core)Application (if needed) etc often dwarfs the running time of the tests themselves! Linking each executable takes up a lot of time, too.

The overhead just kept on increasing as more and more classes were added, and it soon became a problem - one of the goals of unit tests are to have a safety net that runs so fast that it is not a burden at all, and this was rapidly becoming not the case. The solution is to glob multiple test suites into one executable, and while (as shown above) this is mostly do-able, it is not supported and has important limitations.

2) No fixture support - a deal-breaker for me.

So after a while, I switched to Google Test - it is a far more featureful and sophisticated unit testing framework (especially when used with Google Mock) and solves 1) and 2), and moreover, you can still easily use the handy QTestLib features such as QSignalSpy and simulation of GUI events, etc. It was a bit of a pain to switch, but thankfully the project had not advanced too far and many of the changes could be automated.

Personally, I will not be using QtTest over Google Test for future projects - if offers no real advantages that I can see, and has important drawbacks.