qttestlib-tutorial2.qdoc

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// Copyright (C) 2023 The Qt Company Ltd.
// Copyright (C) 2016 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
/*!
    \page qttestlib-tutorial2-example.html
    \previouspage {Chapter 1: Writing a Unit Test}{Chapter 1}
    \nextpage {Chapter 3: Simulating Gui Events}{Chapter 3}
 
    \title Chapter 2: Data Driven Testing
    \brief How to create data driven tests.
 
    This chapter demonstrates how to execute a test multiple times with
    different test data.
 
    So far, we have hard coded the data we wanted to test into our
    test function. If we add more test data, the function might look like
    this:
 
    \snippet code/doc_src_qtestlib.cpp 11
 
    To prevent the function from being cluttered with repetitive code, Qt Test
    supports adding test data to a test function. All we need is to add another
    private slot to our test class:
 
    \snippet tutorial2/testqstring.cpp 0
 
    \section1 Writing the Data Function
 
    A test function's associated data function has \c _data appended to its
    name. Our data function looks like this:
 
    \snippet tutorial2/testqstring.cpp 1
 
    First, we define the two elements of our test table using the \l
    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 \l QTest::newRow()
    function. We can also use \l QTest::addRow() if we need to format some data
    in the row name, for example when generating many data rows iteratively.
    Each row of data will become a separate row in the test table.
 
    \l QTest::newRow() takes one argument: a name that will be associated with
    the data set and used in the test log to identify the data row. \l
    QTest::addRow() takes a (\c{printf}-style) format string followed by the
    parameters to be represented in place of the formatting tokens in the format
    string. 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 \c string and \c result and
    three rows. In addition, a name and an index are associated
    with each row:
 
    \table
    \header
        \li index
        \li name
        \li string
        \li result
    \row
        \li 0
        \li all-lower
        \li "hello"
        \li HELLO
    \row
        \li 1
        \li mixed
        \li "Hello"
        \li HELLO
    \row
        \li 2
        \li all-upper
        \li "HELLO"
        \li HELLO
    \endtable
 
    When data is streamed into the row, each datum is asserted to match
    the type of the column whose value it supplies. If any assertion fails,
    the test is aborted.
 
    The names of rows and columns, in a given test function's data table, should
    be unique: if two rows share a name, or two columns share a name, a warning
    will (since Qt 6.5) be produced. See \l qWarning() for how you can cause
    warnings to be treated as errors and \l {Test for Warnings} for how to get
    your tests clear of other warnings.
 
    \section1 Rewriting the Test Function
 
    Our test function can now be rewritten:
 
    \snippet tutorial2/testqstring.cpp 2
 
    The TestQString::toUpper() function will be executed three times,
    once for each entry in the test table that we created in the
    associated TestQString::toUpper_data() function.
 
    First, we fetch the two elements of the data set using the \l
    QFETCH() macro. \l QFETCH() takes two arguments: The data type of
    the element and the element name. Then, we perform the test using
    the \l QCOMPARE() macro.
 
    This approach makes it very easy to add new data to the test
    without modifying the test itself.
 
    \section1 Preparing the Stand-Alone Executable
 
    And again, to make our test case a stand-alone executable,
    the following two lines are needed:
 
    \snippet tutorial2/testqstring.cpp 3
 
    As before, 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.
 
    \section1 Building the Executable
 
    \include {building-examples.qdocinc} {building the executable} {tutorial2}
 
    \section1 Running the Executable
 
    Running the resulting executable should give you the following
    output:
 
    \snippet code/doc_src_qtestlib.qdoc 11
*/