Qt Unit test in a project



  • Hello,

    I'm quite new to Qt and C++, I used to code in Java. I would like to add unit tests to my project but I'm not really sure that is possible.
    I tried to find a way to do that but I only found a way to create a new projet dedicated to tests.
    In Java the unit test are part of the project and I can run them directly from the project.

    Can you please clear things up to me about Unit tests and Qt project ?

    • Should I make a separate project ?

    • If yes, does it means that I'll need to duplicated every single class of my project ?

    • What are your tips/adivces to start unit tests in C++/Qt ?


  • Moderators

    The Qt build system, qmake, has a concept of "subprojects".

    So, you create a master project file with following contents:

    TEMPLATE = subdirs
    
    SUBDIRS = app tests
    

    Where "app" and "tests" are directories in the same dir where your .pro file is. Inside, there should be normal project files (with names the same as directory name), one will be your app, and the other will contain tests.

    To get easier access to same defines, files etc. in both subprojects, you can put the common definitions in a .pri file, that you then include in project files.

    I know this all sounds complicated (it is), but it's not too hard, just takes a while to get used to. Feel free to check my sTimeline project for reference.





  • @DavidM29 in addition to the good previous replies, you may want to look at Qt MQTT module for an example of how QTestlib is used in a real product.



  • Thank you for the replies !

    I'll take a look a the link you gave me and come back to you if I do have any questions about it.

    @sierdzio I believe your project is going to help me ! Thank you



  • @sierdzio

    How did you made the tests .pro file ? Did you create a separated project ? Did you made it enterily yourself ?
    The .pro files are kind of a dark zone to me I never made any change on them and don't really know how it works.
    I do have the equivalent of the app dir at the moment.
    Should I make 2 new projects ? like one for the master and one for the tests ? How do I merge 2 project into one ?

    "To get easier access to same defines, files etc. in both subprojects, you can put the common definitions in a .pri file, that you then include in project files." Can you explain me a bit more on this ? I don't know what is a .pri file and I found 2 of them in your project without understanding them.

    That is lot of questions... Sorry about that but I would like to implement test like you did. It seems to be close to Java unit tests.
    I don't want to have a separate project where I duplicate my classes to make some tests with. I feel like it is very wrong to do that.



  • @DavidM29

    The .pro files are kind of a dark zone

    They are just plain text files, they don't bite :-)

    Seriously, you can create them from Qt Creator as general files, or create them externally with your favorite editor and place them in the proper/expected folder.

    You may want to read about project files with qmake.


  • Moderators

    @DavidM29 said in Qt Unit test in a project:

    @sierdzio

    How did you made the tests .pro file ? Did you create a separated project ? Did you made it enterily yourself ?

    Yes, hand made.

    The .pro files are kind of a dark zone to me I never made any change on them and don't really know how it works.

    You should learn the syntax, and you should get to know them more. Keeping good project files is just as important part of C++ programming as writing the C++ code itself.

    While you're at it, it is also good to learn cmake, as it has become the de facto standard in C++ world. That one I need to learn myself, too, finally.

    I do have the equivalent of the app dir at the moment.
    Should I make 2 new projects ? like one for the master and one for the tests ? How do I merge 2 project into one ?

    Unfortunately the answer is "doesn't matter" ;-) No matter how you do it, what matters is the result. I recommend writing them by hand. If you currently have your main application project file, then this is super easy. Do this:

    • close Qt Creator
    • remove .pro.user file from your code directory
    • add new dir: app and move your whole project there
    • rename app/yourProject.pro to app/app.pro
    • add new main file in your root dir: yourProject.pro
    • in that file, paste the code I wrote in my previous post
    • open yourProject.pro in Qt Creator

    That's it. You now have a working subdirs project and you can start adding tests. Not sure, maybe even from within Qt Creator (I can't check now).

    "To get easier access to same defines, files etc. in both subprojects, you can put the common definitions in a .pri file, that you then include in project files." Can you explain me a bit more on this ? I don't know what is a .pri file and I found 2 of them in your project without understanding them.

    Since you say you don't know how regular .pro files work, you won't understand anything about .pri files either. The closest (and quite bad) analogy I can draw for you is that .pri is like a header file in C++: you can include it in many source files (.pro) and thus avoid copy pasting.

    I suggest taking a look at your .pro files and trying to make sense of them. Or reading about qmake in some book (or documentation), then things will become clear quickly. qmake syntax is not hard at all.

    That is lot of questions... Sorry about that but I would like to implement test like you did. It seems to be close to Java unit tests.
    I don't want to have a separate project where I duplicate my classes to make some tests with. I feel like it is very wrong to do that.

    Yep.



  • @sierdzio
    Thank you for all the details, I'll probably will have some more question but fisrt I have a bit of work of understanding evrything properly.

    @Pablo-J-Rogina Thank you for the link on .pro files



  • @sierdzio
    Hi,

    I'm done with the project architecture I think. Here is what I have :

    My project : 
    	|- MyProject.pro
    	| - app
    		|- Headers
    			| classToTest.h
    			| ...
    			| ...
    		|- Sources
    			| classToTest.cpp
    			| ...
    			| ...
    		|- Resources
    			|- font.qrc
    			|- image.qrc
    			|- qml.qrc
    	| - tests
    		|- test.pro
    		|- Sources
    			|- testOne.cpp
    

    Is that all good ? (I believe it is I'm able to launch the app properly)

    Now I wonder how should I include the "classToTest.h" inside my testOne.cpp in order to test all the methods of that class.
    Can you please help me with this ?

    PS : I took a look at how you did it on your timeline project and I saw that you made a test project for each class you test. Is that a good practice, you personal choice ? Can I have only the tests project where I have a cpp dedicated to each class I want to test ?

    Thank you in advance


  • Moderators

    @DavidM29 said in Qt Unit test in a project:

    Now I wonder how should I include the "classToTest.h" inside my testOne.cpp

    You need to set http://doc.qt.io/qt-5/qmake-variable-reference.html#includepath in your test.pro
    But this is not enough - you will need to add the cpp file as well (http://doc.qt.io/qt-5/qmake-variable-reference.html#sources)


  • Moderators

    @DavidM29 said in Qt Unit test in a project:

    I saw that you made a test project for each class you test. Is that a good practice, you personal choice ?

    These don't necessarily exclude each other ;-)

    It is my choice. Makes management of all these test subprojects a nightmare (a clear drawback), but it also keeps all components clearly separate (so for example if I were to remove a single class, it's trivial to remove the test as well). Also, it nicely coincides with "unit" part in "unit testing" - each element is tested as a separate entity. Which in turn helps to structure the code so that is is not heavily dependent on other classes and does not evolve into a spaghetti. Also, it plays nice with Qt Creator automated test runner.

    I don't know if it is the best solution, probably not.



  • Thank for the answers !

    @jsulm
    Why should I include the cpp file instead of the header which are the file we usualy use to reuse function from another class ? Is that because it is a different project ?

    @sierdzio
    Ok, what do you think about my idea of keeping only one tests project with multiple cpp file corresponding to each class I want to test ?


  • Moderators

    @DavidM29 said in Qt Unit test in a project:

    Why should I include the cpp file instead of the header which are the file we usualy use to reuse function from another class ? Is that because it is a different project ?

    Because you want to test the code there, right? Your test will be an executable and header file alone is not enough (you will get "Undefined symbol" linker errors, just try).


  • Moderators

    @DavidM29 said in Qt Unit test in a project:

    Thank for the answers !

    @jsulm
    Why should I include the cpp file instead of the header which are the file we usualy use to reuse function from another class ? Is that because it is a different project ?

    C++ compiler needs to compile your class to use it in a test. And in order to compile, it needs the cpp file.

    @sierdzio
    Ok, what do you think about my idea of keeping only one tests project with multiple cpp file corresponding to each class I want to test ?

    Sounds good.



  • Thank you to all of you it seems that I'm all set. My first try seems to works nicely.


  • Moderators

    Nice! Happy coding :-)


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