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A lightweight library to simplify and generalize the process of writing unit tests for C applications.


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Cmockery Unit Testing Framework

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Cmockery is a lightweight library that is used to author C unit tests.


Cmockery tests are compiled into stand-alone executables and linked with the Cmockery library, the standard C library, and the module being tested. Any symbols external to the module being tested should be mocked - replaced with functions that return values determined by the test - within the test application. Even though significant differences may exist between the target execution environment of a code module and the environment used to test the code, the unit testing is still valid since its goal is to test the logic of a code modules at a functional level and not necessarily all of its interactions with the target execution environment.

It may not be possible to compile a module into a test application without some modification; therefore, the preprocessor symbol UNIT_TESTING should be defined when Cmockery unit test applications are compiled so code within the module can be conditionally compiled for tests.

More detailed information about the mechanics of writing tests with Cmockery can be found in docs/


To compile the Cmockery library and example applications on Linux, run:

$ ./configure
$ make

To compile on Windows, run:

> vsvars.bat
> cd windows
> nmake

This code has been tested on Linux (Ubuntu) and Windows using VC++7 and VC++8.


There are a variety of C unit testing frameworks available; however, many of them are fairly complex and require the latest compiler technology. Some development requires the use of old compilers which makes it difficult to use some unit testing frameworks. In addition, many unit testing frameworks assume the code being tested is an application or module that is targeted to the same platform that will ultimately execute the test. Because of this assumption, many frameworks require the inclusion of standard C library headers in the code module being tested, which may collide with the custom or incomplete implementation of the C library utilized by the code under test.

Cmockery only requires a test application is linked with the standard C library which minimizes conflicts with standard C library headers. Also, Cmockery tries avoid the use of some of the newer features of C compilers.

This results in Cmockery being a relatively small library that can be used to test a variety of exotic code. If a developer wishes to simply test an application with the latest compiler, then other unit testing frameworks may be preferable.


If you have questions about Cmockery, use the following resources:

  • Stack Overflow: use the cmockery tag

  • Mailing list: cmockery (at) (archives)

    To join with a Google account, use the web UI; to subscribe/unsubscribe with an arbitrary email address, send an email to:

    • cmockery+subscribe (at)
    • cmockery+unsubscribe (at)


Cmockery is licensed under the Apache 2.0 license; please see LICENSE.txt for details.