The content access module ist important to work properly for us (especially concerning security), so I coded some Simpletests for this module (for the Drupal 5 version).
There are two test files: one does tests on content type access and per node access, the other one does tests in combination with the ACL module. Both use a parent class that provides some common functions.
I'm sorry, but I was not able to create a patch from the command line (because there is a new subdirectory "tests", the documentation on http://drupal.org/patch/create did not give information for that).
So just put the files in a new subdirectory "tests" in content_access (and rename the file "content_access_test_help.php_.txt" to "content_access_test_help.php")