Introducing cfix, a unit testing framework for C/C++ on Win32

I am happy to announce that the unit testing framework cfix I have developed over the past weeks and months is now available on Sourceforge as a first release candidate. It is licensed under the GPL, both binaries and source code are available.


cfix is a framework for authoring and running xUnit-like testcases written in C or C++. The aim of the tool is to provide a development experience very similar to frameworks such as JUnit or NUnit. Due to the nature of C and C++, current unit testing frameworks for C and C++ hardly reach the ease of use of JUnit or NUnit. In particular, it is noticable that significantly more code has to be written to implement a test suite.

Languages like Java and the various .Net languages, as well as scripting languages, all provide reflection facilities. Unit testing frameworks for these languages can therefore rely on reflective features in order to minimize the amount of code required to define a test suite. Provided a library, the framework can find and identify test cases and is able to selectively run them.

Lacking similar reflective facilities, the route most unit testing frameworks for C and C++ have chosen is to oblige the developer to explicitly define test cases and fixtures. Taking CUnit as an example, the developer has to make explictit function calls to define a test suite, add test cases to the suite and to finally run this suite. CppUnit simplifies this a bit, but still requires the developer to implement quite some amount of initialization code. Another important drawback of this approach is the fact that no real separation between test code and test runner is done. Often, even the choice whether to use a graphical or a console frontend for running test is tied to this initialization code.

The aim of cfix is to overcome these limitations and to provide an easy to use, yet powerful unit testing framework for C and C++. Rather than having to write tedious initialization code, the developer merely has to define a fixture using the macros shown in the example below.

Like JUnit and NUnit (but unlike all frameworks for C/C++, with WinUnit being the notable exception), cfix implements a separation in between test code and the test runner. Unit tests are compiled into a DLL rather than an EXE file. This DLL thus only contains the code to be tested. The entire logic and user interface required to actually run unit tests is contained in the cfix-provided testrunner, cfix32.exe/cfix64.exe.

Moreover, cfix has been designed to make debugging of unit tests as easy as possible — the frameworks notices when a debugger is present and allows you to break in as soon as some assertion fails.


So let’s have a look at a minimalistic cfix unit test:


void Test1()
  int a = 1;
  int b = 1;
  CFIX_ASSERT( a + b == 2 );

CFIX_BEGIN_FIXTURE( MyMinimalisticFixture )

After compiling and linking the code into a DLL using

cl /Zi /LD cfix-sample.c

the unit test can be run with the testrunner cfix32 (or cfix64):

[Success]      cfix-sample.dll.MyMinimalisticFixture.Test1

Needless to say, cfix is not limited to such simple tests — have a look at the Tutorial to learn more about the features, installation and usage of cfix.

Enough background information — go ahead and…

Of course, I’d love to read your feedback — you can reach me via passing at!


3 Responses to “Introducing cfix, a unit testing framework for C/C++ on Win32”

  1. 1 PYates March 21, 2011 at 1:01 pm


    I am a tester and not a developer so I was wondering if there were an any more indepth tutorial.

  1. 1 cfix 1.0.0 released « JP’s Blog Trackback on April 3, 2008 at 8:00 am
  2. 2 Embracing WinUnit « JP’s Blog Trackback on February 26, 2009 at 5:53 pm
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About me

Johannes Passing, M.Sc., living in Berlin, Germany.

Besides his consulting work, Johannes mainly focusses on Win32, COM, and NT kernel mode development, along with Java and .Net. He also is the author of cfix, a C/C++ unit testing framework for Win32 and NT kernel mode, Visual Assert, a Visual Studio Unit Testing-AddIn, and NTrace, a dynamic function boundary tracing toolkit for Windows NT/x86 kernel/user mode code.

Contact Johannes: jpassing (at) acm org

Johannes' GPG fingerprint is BBB1 1769 B82D CD07 D90A 57E8 9FE1 D441 F7A0 1BB1.

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