Welcome to a simple example of how Mayhem can be used to improve a simple calculator app. In a nutshell, Mayhem tries to test your app like a hacker and help you check high level requirements in addition to specific unit tests.

Check out the PR to see how Mayhem works by:

• Performing security testing. Security testing searches and proves vulnerabililties
  such as memory safety and logical bugs that violate a program invariant.

• Improving coverage. Mayhem continually looks for untested code and then writes a test case for it. The algorithm works as follows. Mayhem runs the app on a specific input, and notices which code branches are not executed. Those code branches are added to a queue. Mayhem then processes the queue and tries to write a test case that triggers a previously untested branch. Over time, this process helps grow your test suite to get more code coverage.

• Checking requirements with property testing. Unit tests only check a single test case, thus are insufficient for checking that general requirements hold. Property testing extends unit testing to check that all variations of a test satisfy an output condition.

  For example, Mayhem can check "A * B / A = B", while normal unit tests can only check specific cases like "3 * 2 / 3 = 2".

You can build this application quickly in two ways:

# docker build.
make docker

# On-system build. Requires make and a C compiler.
make all

1. Go to https://mayhem.security and create an account.
2. Build the docker image as given in the quick start. Push the docker image to a public docker registry
3. Edit tests/Mayhemfile to point to your docker image.
4. Run mayhem run -f tests/Mayhemfile.