This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Chapter 1: Writing a Unit Test#

How to write a unit test.

This first chapter demonstrates how to write a simple unit test and how to run the test case as a stand-alone executable.

Writing a Test#

Let’s assume you want to test the behavior of our QString class. First, you need a class that contains your test functions. This class has to inherit from QObject:

from PySide6.QtTest import QTest
class TestQString(QObject):

# private slots
    def toUpper():


You need to include the QTest header and declare the test functions as private slots so the test framework finds and executes it.

Then you need to implement the test function itself. The implementation could look like this:

def toUpper(self):

    str = "Hello"
    QVERIFY(str.toUpper() == "HELLO")

The QVERIFY() macro evaluates the expression passed as its argument. If the expression evaluates to true, the execution of the test function continues. Otherwise, a message describing the failure is appended to the test log, and the test function stops executing.

But if you want a more verbose output to the test log, you should use the QCOMPARE() macro instead:

def toUpper(self):

    str = "Hello"
    QCOMPARE(str.toUpper(), QString("HELLO"))

If the strings are not equal, the contents of both strings are appended to the test log, making it immediately visible why the comparison failed.

Preparing the Stand-Alone Executable#

Finally, to make our test case a stand-alone executable, the following two lines are needed:

from testqstring.moc import *

The QTEST_MAIN() macro expands to a simple main() method that runs all the test functions. Note that if both the declaration and the implementation of our test class are in a .cpp file, we also need to include the generated moc file to make Qt’s introspection work.

Building the Executable#

You can build the test case executable using CMake or qmake.

Building with CMake#

Configure your build settings in your CMakeLists.txt file:

<Code snippet "/data/qt5-full-663/6.6.3/Src/qtbase/tutorial1/CMakeLists.txt" not found>

Next, from the command line, run either cmake or use the qt-cmake convenience script located in Qt-prefix/<version>/<platform>/bin/qt-cmake:

<Qt-prefix>/<version>/<platform>/bin/qt-cmake <source-dir> <build-dir> -G Ninja

Then, run your preferred generator tool to build the executable. Here, we’re using Ninja:


Building with qmake#

Configure your build settings in your .pro file:

<Code snippet "/data/qt5-full-663/6.6.3/Src/qtbase/tutorial1/tutorial1.pro" not found>

Next, run qmake, and, finally, run make to build your executable:



If you’re using windows, replace make with nmake or whatever build tool you use.

Running the Executable#

Running the resulting executable should give you the following output:

********* Start testing of TestQString *********
Config: Using QtTest library %VERSION%, Qt %VERSION%
PASS   : TestQString::initTestCase()
PASS   : TestQString::toUpper()
PASS   : TestQString::cleanupTestCase()
Totals: 3 passed, 0 failed, 0 skipped
********* Finished testing of TestQString *********

Congratulations! You just wrote and executed your first unit test using the Qt Test framework.