Chapter 2: Data Driven Testing

Writing the Data Function

A test function's associated data function carries the same name, appended by _data. Our data function looks like this:

    void TestQString::toUpper_data()
    {
        QTest::addColumn<QString>("string");
        QTest::addColumn<QString>("result");

        QTest::newRow("all lower") << "hello" << "HELLO";
        QTest::newRow("mixed")     << "Hello" << "HELLO";
        QTest::newRow("all upper") << "HELLO" << "HELLO";
    }

First, we define the two elements of our test table using the QTest::addColumn() function: A test string, and the expected result of applying the QString::toUpper() function to that string.

Then we add some data to the table using the QTest::newRow() function. Each set of data will become a separate row in the test table.

QTest::newRow() takes one argument: A name that will be associated with the data set. If the test fails, the name will be used in the test log, referencing the failed data. Then we stream the data set into the new table row: First an arbitrary string, and then the expected result of applying the QString::toUpper() function to that string.

You can think of the test data as a two-dimensional table. In our case, it has two columns called string and result and three rows. In addition a name as well as an index is associated with each row:

    void TestQString::toUpper()
    {
        QFETCH(QString, string);
        QFETCH(QString, result);

        QCOMPARE(string.toUpper(), result);
    }

    QTEST_MAIN(TestQString)
    #include "testqstring.moc"