def test_file_exists(self): oid = self.fs.put(b"hello") self.assertRaises(FileExists, self.fs.put, b"world", _id=oid) one = self.fs.new_file(_id=123) one.write(b"some content") one.close() two = self.fs.new_file(_id=123) self.assertRaises(FileExists, two.write, b'x' * 262146)