Running tests for your system call is easy.
From your working directory, run ~cs537-1/tests/P2/tester/runtests -d ~cs537-1/tests/P2/initial-xv6/tests
If you want to run all the tests despite any failures, use ~cs537-1/tests/P2/tester/runtests -d ~cs537-1/tests/P2/initial-xv6/tests -c
The pregrade script will also work, so once you are ready to handin, once you have copied your files to your handin directory, you can run it to ensure that your submission has the correct folder/file structure.