Chapter 3: Simulating GUI Events

Qt Test features some mechanisms to test graphical user interfaces. Instead of simulating native window system events, Qt Test sends internal Qt events. That means there are no side-effects on the machine the tests are running on.

In this chapter we will see how to write a simple GUI test.

Writing a GUI Test

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.

Note: The widget must also be shown in order to correctly test keyboard shortcuts.

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.

Example project @ code.qt.io