Also just realized that there should be tests for your validation.

So for each one param that you added, create a few tests where you give it some valid values that should contain_file and a test where you give it an invalid value and it should have the Error with the message from the manifest. For these, you only need to check the contents of the sshd_config, since that is what you are testing. Do not bother testing if the package is there, the service is running and so on.