Chapter 3: Simulating GUI Events

This time, let's assume you want to test the behavior of our QLineEdit class. As before, you will need a class that contains your test function:

#include <QtWidgets>
#include <QTest>

class TestGui: public QObject
{
    Q_OBJECT

private slots:
    void testGui();

};

The only difference is that you need to include the Qt GUI class definitions in addition to the QTest namespace.

void TestGui::testGui()
{
    QLineEdit lineEdit;

    QTest::keyClicks(&lineEdit, "hello world");

    QCOMPARE(lineEdit.text(), QString("hello world"));
}

In the implementation of the test function, we first create a QLineEdit. Then, we simulate writing "hello world" in the line edit using the QTest::keyClicks() function.

QTest::keyClicks() simulates clicking a sequence of keys on a widget. Optionally, a keyboard modifier can be specified as well as a delay (in milliseconds) of the test after each key click. In a similar way, you can use the QTest::keyClick(), QTest::keyPress(), QTest::keyRelease(), QTest::mouseClick(), QTest::mouseDClick(), QTest::mouseMove(), QTest::mousePress() and QTest::mouseRelease() functions to simulate the associated GUI events.

Finally, we use the QCOMPARE() macro to check if the line edit's text is as expected.

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

QTEST_MAIN(TestGui)
#include "testgui.moc"

The QTEST_MAIN() macro expands to a simple main() method that runs all the test functions, and since 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.

Building with CMake▲

# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: BSD-3-Clause

cmake_minimum_required(VERSION 3.16)
project(tutorial3 LANGUAGES CXX)

if(NOT DEFINED INSTALL_EXAMPLESDIR)
    set(INSTALL_EXAMPLESDIR "examples")
endif()

set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/qtestlib/tutorial3")

find_package(Qt6 REQUIRED COMPONENTS Core Gui Test Widgets)

qt_standard_project_setup()

qt_add_executable(tutorial3
    testgui.cpp
)

set_target_properties(tutorial3 PROPERTIES
    WIN32_EXECUTABLE TRUE
    MACOSX_BUNDLE TRUE
)

target_link_libraries(tutorial3 PRIVATE
    Qt6::Core
    Qt6::Gui
    Qt6::Test
    Qt6::Widgets
)

install(TARGETS tutorial3
    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
)

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

ninja

Building with qmake▲

QT += widgets testlib

SOURCES = testgui.cpp

# install
target.path = $$[QT_INSTALL_EXAMPLES]/qtestlib/tutorial3
INSTALLS += target

qmake
make

Running the resulting executable should give you the following output:

********* Start testing of TestGui *********
Config: Using QtTest library %VERSION%, Qt %VERSION%
PASS   : TestGui::initTestCase()
PASS   : TestGui::testGui()
PASS   : TestGui::cleanupTestCase()
Totals: 3 passed, 0 failed, 0 skipped, 0 blacklisted, 20ms
********* Finished testing of TestGui **