C TAP Harness comes with a comprehensive test suite, which you can run
after building with:

```
    make check
```

If a test fails, you can run a single test with verbose output via:

```
    ./runtests -b `pwd`/tests -s `pwd`/tests -o <name-of-test>
```

Do this instead of running the test program directly since it will ensure
that necessary environment variables are set up.  You may need to change
the `-s` option argument if you build with a separate build directory from
the source directory.