'A L{FileLogObserver} returned by L{jsonFileLogObserver} is an
L{ILogObserver}.'

def test_interface(self):

    with StringIO() as fileHandle:
        observer = jsonFileLogObserver(fileHandle)
        try:
            verifyObject(ILogObserver, observer)
        except BrokenMethodImplementation as e:
            self.fail(e)
