def opt_testmodule(self, filename):
        """
        Filename to grep for test cases (-*- test-case-name).
        """
        # If the filename passed to this parameter looks like a test module
        # we just add that to the test suite.
        #
        # If not, we inspect it for an Emacs buffer local variable called
        # 'test-case-name'.  If that variable is declared, we try to add its
        # value to the test suite as a module.
        #
        # This parameter allows automated processes (like Buildbot) to pass
        # a list of files to Trial with the general expectation of "these files,
        # whatever they are, will get tested"
        if not os.path.isfile(filename):
            sys.stderr.write("File %r doesn't exist\n" % (filename,))
            return
        filename = os.path.abspath(filename)
        if isTestFile(filename):
            self['tests'].append(filename)
        else:
            self['tests'].extend(getTestModules(filename))

        Filename to grep for test cases (-*- test-case-name).
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/scripts/trial.py