theft is a C library for property-based testing. Where example-based testing checks test results for specific input, theft tests assert general properties ("for any possible input, [some condition] should hold"), generate input, and search for counter-examples that make the test fail. If theft finds any failures, it also knows how to generate and test simpler variants of the input, and then report the simplest counter-example found.
theft is distributed under the ISC license.
theft does not depend on anything beyond C99 and a Unix-like environment. Its internal tests use greatest, but there is not any coupling between them. It contains implementations of the Mersenne Twister PRNG and the FNV-1a hashing algorithm - see their files for copyright info.
To build, using GNU make:
$ make
Note: You may need to call it as gmake, especially if building on BSD.
To build and run the tests:
$ make test
This will produce example output from several falsifiable properties, and confirm that failures have been found.
To install libtheft and its headers:
$ make install # using sudo, if necessary
theft can also be vendored inside of projects -- in that case, just make
sure the headers in ${VENDOR}/theft/inc/ are added to the -I include
path, and ${VENDOR}/theft/build/libtheft.a is linked.
For usage documentation, see doc/usage.md.
For some examples of properties to test, see doc/properties.md.
For more info about shrinking and auto-shrinking, see doc/shrinking.md.
theft can fork before running properties, to shrink failures that make the code under test crash or exceed an optional timeout. For more info, see doc/forking.md.