def METHOD_NAME(self):
    with self.open(TESTFN, 'rb') as f:
        self.assertEqual(os.lseek(f.fileno(), 0, 0), 0)
        self.assertEqual(os.lseek(f.fileno(), 42, 0), 42)
        self.assertEqual(os.lseek(f.fileno(), 42, 1), 84)
        self.assertEqual(os.lseek(f.fileno(), 0, 1), 84)
        self.assertEqual(os.lseek(f.fileno(), 0, 2), size+1+0)
        self.assertEqual(os.lseek(f.fileno(), -10, 2), size+1-10)
        self.assertEqual(os.lseek(f.fileno(), -size-1, 2), 0)
        self.assertEqual(os.lseek(f.fileno(), size, 0), size)
        # the 'a' that was written at the end of file above
        self.assertEqual(f.read(1), b'a')