def test_memory_backend_errors():
backend = MemoryBackend(1) # seconds
backend.set('key', t, 'value')
[[time, value]] = backend.get('key',
start=datetime.now() - timedelta(seconds=0.5),
end=datetime.now())
assert type(time) is datetime
assert value == 'value'
with raises(BackendError):
print(backend.get('key',
start=datetime.now() - timedelta(seconds=1.5),
end=datetime.now()))
