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# Chapter 3: Simulating GUI Events

[Previous: Chapter 2: Data Driven Testing][QTestLib Tutorial][Next: Chapter 4: Replaying GUI Events]

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

In this chapter we will se 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:
The following code example is written in c++.

    #include <QtGui>
    #include <QtTest/QtTest>

    class TestGui: public QObject
    {
        Q_OBJECT

    private slots:
        void testGui();

    };

The only difference is that you need to include the QtGui class definitions in addition to the QTest namespace.
The following code example is written in c++.

    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:
The following code example is written in c++.

    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.