To build the test cases, run from the test directory:

nix-build --no-out-link default.nix

To run all tests (includes impure tests), use the script:

./tests.sh

If you change the test Cabal files or need to regenerate the code with nix-tools, then see regen.nix. Run it like this:

$(nix-build --no-out-link regen.nix)