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QTestLib Manual

An overview of Qt's unit testing framework. The QTestLib framework, provided by Nokia, is a tool for unit testing Qt based applications and libraries. QTestLib provides all the functionality commonly found in unit testing frameworks as well as extensions for testing graphical user interfaces.

Table of contents:

QTestLib Features

QTestLib is designed to ease the writing of unit tests for Qt based applications and libraries:
Lightweight QTestLib consists of about 6000 lines of code and 60 exported symbols.
Self-contained QTestLib requires only a few symbols from the Qt Core library for non-gui testing.
Rapid testing QTestLib needs no special test-runners; no special registration for tests.
Data-driven testing A test can be executed multiple times with different test data.
Basic GUI testing QTestLib offers functionality for mouse and keyboard simulation.
Benchmarking QTestLib supports benchmarking and provides several measurement back-ends.
IDE friendly QTestLib outputs messages that can be interpreted by Visual Studio and KDevelop.
Thread-safety The error reporting is thread safe and atomic.
Type-safety Extensive use of templates prevent errors introduced by implicit type casting.
Easily extendable Custom types can easily be added to the test data and test output.
Note: For higher-level GUI and application testing needs, please see the Qt testing products provided by Nokia partners.

QTestLib API

All public methods are in the QTest namespace. In addition, the QSignalSpy class provides easy introspection for Qt's signals and slots.

Using QTestLib

Creating a Test

To create a test, subclass
QObject and add one or more private slots to it. Each private slot is a testfunction in your test. QTest::qExec() can be used to execute all testfunctions in the test object.

In addition, there are four private slots that are not treated as testfunctions. They will be executed by the testing framework and can be used to initialize and clean up either the entire test or the current test function.

If initTestCase() fails, no testfunction will be executed. If init() fails, the following testfunction will not be executed, the test will proceed to the next testfunction.


class MyFirstTest: public QObject
private slots:
    void initTestCase()
    { qDebug("called before everything else"); }
    void myFirstTest()
    { QVERIFY(1 == 1); }
    void mySecondTest()
    { QVERIFY(1 != 2); }
    void cleanupTestCase()
    { qDebug("called after myFirstTest and mySecondTest"); }
For more examples, refer to the QTestLib Tutorial.

Building a Test

If you are using qmake as your build tool, just add the following to your project file:
QT += testlib
If you are using other buildtools, make sure that you add the location of the
QTestLib header files to your include path (usually include/QtTest under your Qt installation directory). If you are using a release build of Qt, link your test to the QtTest library. For debug builds, use QtTest_debug.

See Writing a Unit Test for a step by step explanation.

QTestLib Command Line Arguments


The syntax to execute an autotest takes the following simple form:
testname [options] [testfunctions[:testdata]]...
Substitute testname with the name of your executable. testfunctions can contain names of test functions to be executed. If no testfunctions are passed, all tests are run. If you append the name of an entry in testdata, the test function will be run only with that test data.

For example:

/myTestDirectory$ testQString toUpper
Runs the test function called toUpper with all available test data.
/myTestDirectory$ testQString toUpper toInt:zero
Runs the toUpper test function with all available test data, and the toInt test function with the testdata called zero (if the specified test data doesn't exist, the associated test will fail).
/myTestDirectory$ testMyWidget -vs -eventdelay 500
Runs the testMyWidget function test, outputs every signal emission and waits 500 milliseconds after each simulated mouse/keyboard event.


The following command line arguments are understood:

Creating a Benchmark

To create a benchmark, follow the instructions for crating a test and then add a QBENCHMARK macro to the test function that you want to benchmark.
class MyFirstBenchmark: public QObject
private slots:
    void myFirstBenchmark()
        QString string1;
        QString string2;
        QBENCHMARK {
The code insde the QBENCHMARK macro will be measured, and possibly also repeated several times in order to get an accurate measurement. This depends on the selected measurement back-end. Several back-ends are available an can be selected on the command line:
Commmand-line Arguemnt
Walltime (default) All platforms
CPU tick counter -tickcounter Windows, Mac OS X, Linux, many UNIX-like systems.
Valgrind/Callgrind -callgrind Linux (if installed)
Event Counter -eventcounter All platforms
In short, walltime is always available but requires many repetitions to get a useful result. Tick counters are usually available and can provide results with fewer repetitions, but can be susceptible to CPU frequency scaling issues. Valgrind provides exact results, but does not take I/O waits into account, and is only available on a limited number of platforms. Event counting is available on all platforms and it provides the number of events that were received by the event loop before they are sent to their corresponding targets (this might include non-Qt events).

See the chapter 5 in the QTestLib Tutorial for more benchmarking examples.

Using QTestLib remotely on Windows CE

cetest is a convenience application which helps the user to launch an application remotely on a Windows CE device or emulator.

It needs to be executed after the unit test has been successfully compiled.

Prior to launching, the following files are copied to the device:

Using cetest



The syntax to execute an autotest takes the following simple form:
cetest [options] ...


cetest provides the same options as those for unit-testing on non cross-compiled platforms. See
Command Line Arguments for more information.

The following commands are also included:

Note:debug is the default build option.


QtRemote is a small library which is build after
QTestLib. It allows the host system to create a process on a remote device and waits until its execution has been finished.


cetest uses Microsoft ActiveSync to establish a remote connection between the host computer and the device. Thus header files and libraries are needed to compile cetest and
QtRemote successfully.

Prior to installation of Qt, you need to set your INCLUDE and LIB environment variables properly.

A default installation of Windows Mobile 5 for Pocket PC can be obtained by:

set INCLUDE=C:\Program Files\Windows CE Tools\wce500\Windows Mobile 5.0 Pocket PC SDK\Activesync\Inc;%INCLUDE%
set LIB=C:\Program Files\Windows CE Tools\wce500\Windows Mobile 5.0 Pocket PC SDK\Activesync\Lib;%LIB%    
Note that Qt will remember the path, so you do not need to set it again after switching the environments for cross-compilation.

3rd Party Code

The CPU tick counters used for benchmarking is licensed under the following license: (from src/testlib/3rdparty/cycle.h)Copyright (c) 2003, 2006 Matteo Frigo
Copyright (c) 2003, 2006 Massachusetts Institute of TechnologyPermission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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