(Relatively) Easy Unit Testing in C
C Shell Makefile
Latest commit f048c28 Apr 2, 2016 @phf phf committed with Switch from _exit() to exit(), rework fflush().
CT runs each test case and benchmark in its own process; those processes
end with a call to _exit(). However, gcov writes coverage data in an
atexit() function which doesn't get called from _exit(). So we switch to
exit() to enable test coverage analysis. Since exit() flushes files, we
had to rework our fflush() strategy as well.
Failed to load latest commit information.
ct Switch from _exit() to exit(), rework fflush(). Apr 3, 2016
Makefile check and fix const strings Mar 8, 2016
msg.c check and fix const strings Mar 8, 2016



(Relatively) Easy Unit Testing for C

How to use

  1. Copy subdirectory ct into your project.
  2. Add some rules to your makefile. See Makefile for an example.
  3. Write some tests. See msg-test.c for an example. Test function names begin with "cttest".
  4. Run make check


  • The test runner runs each test in a separate process, so global state from one test will not affect another.
  • Each test is run in a new process group; all processes in the group will be killed after the test finishes. This means your test can fork without having to worry about cleaning up its descendants.
  • CT participates in GNU make's jobserver protocol. If you put a + in front of the _ctcheck command (as in the sample makefile) and run make with its -jN flag, for example make -j16 check, CT will run tests concurrently (and hopefully in parallel).
  • A scratch directory can be obtained by calling ctdir() inside the test. This directory will be removed by the test runner after the test finishes.
  • If you want to perform test coverage analysis using gcov please be aware that gcov is not necessarily multi-process-safe. If you get strange coverage data, try -j1 and avoid forking in your test cases.

Terminal Output

Running make -j4 check in the example supplied looks like this:

$ make -j4 check
cc -Werror -Wall -Wformat=2   -c -o msg-test.o msg-test.c
cc -Werror -Wall -Wformat=2   -c -o ct/ct.o ct/ct.c
cc -Werror -Wall -Wformat=2   -c -o msg.o msg.c
ct/gen msg-test.o > ct/_ctcheck.c.part
mv ct/_ctcheck.c.part ct/_ctcheck.c
cc -Werror -Wall -Wformat=2   -c -o ct/_ctcheck.o ct/_ctcheck.c
cc   ct/_ctcheck.o ct/ct.o msg.o msg-test.o   -o ct/_ctcheck


Remove some of the return statements in msg-test.c to see what various errors and failures look like.


There will be no releases of this tool. Just clone the latest source from git and copy it into your project. If you want to update, copy the newer source into your project.


Inspired by CUT 2.1 by Sam Falvo and Billy Tanksley. Also with ideas from the Go testing package and gotest. Also stole some benchmark hints from testingbee by Dustin Sallings.