Run bundle then rake or if you want to avoid bundler ruby test/test.rb.
This runs Brakeman against full apps in the apps directory and checks the results against what is expected.
Run cd test && ruby to_test.rb apps/some_app > tests/some_app.rb to generate a test suite with tests for each warning reported.
Run ruby test/tests/some_file.rb to run a single file of tests.
Ruby ruby test/test.rb --name test_something to run a single test.