The error indicates it doesn't know where that Movie::NoDirectorError
exception class is defined. You might need to specifically require
the file where that class is defined or the test may not be able to find it.
Rails will automatically attempt to locate any constant missing
constants using a conventional file directory format. It will look for a file in the load_path
at movie/no_director_error
and movie
based on the name of the constant. If the file is not found or the file doesn't define the expected constant than you'll need to specifically require the file yourself.