def setUp(self):
        """
        Create a temporary file with a fixed payload of 64 bytes.  Create a
        resource for that file and create a request which will be for that
        resource.  Each test can set a different range header to test different
        aspects of the implementation.
        """
        path = FilePath(self.mktemp())
        # This is just a jumble of random stuff.  It's supposed to be a good
        # set of data for this test, particularly in order to avoid
        # accidentally seeing the right result by having a byte sequence
        # repeated at different locations or by having byte values which are
        # somehow correlated with their position in the string.
        self.payload = (b'\xf8u\xf3E\x8c7\xce\x00\x9e\xb6a0y0S\xf0\xef\xac\xb7'
                        b'\xbe\xb5\x17M\x1e\x136k{\x1e\xbe\x0c\x07\x07\t\xd0'
                        b'\xbckY\xf5I\x0b\xb8\x88oZ\x1d\x85b\x1a\xcdk\xf2\x1d'
                        b'&\xfd%\xdd\x82q/A\x10Y\x8b')
        path.setContent(self.payload)
        self.file = path.open()
        self.resource = static.File(self.file.name)
        self.resource.isLeaf = 1
        self.request = DummyRequest([b''])
        self.request.uri = self.file.name
        self.catcher = []
        log.addObserver(self.catcher.append)

        Create a temporary file with a fixed payload of 64 bytes.  Create a
        resource for that file and create a request which will be for that
        resource.  Each test can set a different range header to test different
        aspects of the implementation.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_static.py