If you have frozen rails in your project then the many rails tests
will be distributed in various directories like
And actionpack (which contains ActionController and ActionView) and
activerecord also have readme files called RUNNING_UNIT_TESTS with
instructions on how to run those tests.
If you are using rails from gems they will be in the individual gems.
But normally you don't run these tests in projects, they are really
for testing when rails itself is modified/patched, and the tests are
run by patch developers and the rails committers before changes are
Bear in mind that some of the rails tests require their own databases
to be set up, which is covered in those RUNNING_UNIT_TESTS readmes.