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Qt Test Tutorial Overview Chapter 2
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.
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:
#include <QTest> class TestQString: public QObject { Q_OBJECT private slots: void toUpper(); };
Note: 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:
void TestQString::toUpper() { QString 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:
void TestQString::toUpper() { QString 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.
Finally, to make our test case a stand-alone executable, the following two lines are needed:
QTEST_MAIN(TestQString)
#include "testqstring.moc"
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.
You can build the test case executable using CMake or qmake.
Configure your build settings in your CMakeLists.txt file:
cmake_minimum_required(VERSION 3.16) project(tutorial1 LANGUAGES CXX) set(CMAKE_AUTOMOC ON) if(NOT DEFINED INSTALL_EXAMPLESDIR) set(INSTALL_EXAMPLESDIR "examples") endif() set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/qtestlib/tutorial1") find_package(Qt6 REQUIRED COMPONENTS Core Gui Test Widgets) qt_add_executable(tutorial1 testqstring.cpp ) set_target_properties(tutorial1 PROPERTIES WIN32_EXECUTABLE TRUE MACOSX_BUNDLE TRUE ) target_link_libraries(tutorial1 PUBLIC Qt::Core Qt::Gui Qt::Test Qt::Widgets ) install(TARGETS tutorial1 RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}" BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}" LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}" )
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:
ninja
Configure your build settings in your .pro
file:
QT += widgets testlib SOURCES = testqstring.cpp # install target.path = $$[QT_INSTALL_EXAMPLES]/qtestlib/tutorial1 INSTALLS += target
Next, run qmake
, and, finally, run make
to build your executable:
qmake make
Note: If you're using windows, replace make
with nmake
or whatever build tool you use.
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.
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