CODEWITHSUNDEEP
pythonunit-testingmockingpython-mock
Houman
Houman

Reputation: 66320

How to mock a redis client in Python?

I just found that a bunch of unit tests are failing, due a developer hasn't mocked out the dependency to a redis client within the test. I'm trying to give a hand in this matter but have difficulties myself.

The method writes to a redis client:

redis_client = get_redis_client()
redis_client.set('temp-facility-data', cPickle.dumps(df))

Later in the assert the result is retrieved:

res = cPickle.loads(get_redis_client().get('temp-facility-data'))
expected = pd.Series([set([1, 2, 3, 4, 5])], index=[1])
assert_series_equal(res.variation_pks, expected)

I managed to patch the redis client's get() and set() successfully.

@mock.patch('redis.StrictRedis.get')
@mock.patch('redis.StrictRedis.set')
def test_identical(self, mock_redis_set, mock_redis_get):
    mock_redis_get.return_value = ???
    f2 = deepcopy(self.f)
    f3 = deepcopy(self.f)
    f2.pk = 2
    f3.pk = 3
    self.one_row(f2, f3)

but I don't know how to set the return_value of get() to what the set() would set in the code, so that the test would pass.

Right now this line fails the test:

res = cPickle.loads(get_redis_client().get('temp-facility-data'))
TypeError: must be string, not MagicMock

Any advice please?

Upvotes: 32

Views: 34569

Answers (3)

Narek
Narek

Reputation: 616

If you want something more complete, you can try fakeredis

@patch("redis.Redis", return_value=fakeredis.FakeStrictRedis())
def test_something():
....

Upvotes: 8

Akarshan
Akarshan

Reputation: 31

I think you can do something like this.

redis_cache = {
    "key1": (b'\x80\x04\x95\x08\x00\x00\x00\x00\x00\x00\x00\x8c\x04test\x94.', "test"),
    "key2": (None, None),
}
    
def get(redis_key):
    if redis_key in redis_cache:
        return redis_cache[redis_key][0]
    else:
        return None
    
mock = MagicMock()
mock.get = Mock(side_effect=get)
    
with patch('redis.StrictRedis', return_value=mock) as p:
    for key in redis_cache:
        result = self.MyClass.my_function(key)
        self.assertEqual(result, redis_cache[key][1])

Upvotes: 1

user3012759
user3012759

Reputation: 2095

Think you can use side effect to set and get value in a local dict

data = {}
def set(key, val):
    data[key] = val

def get(key):
    return data[key]

mock_redis_set.side_effect = set
mock_redis_get.side_effect = get

not tested this but I think it should do what you want

Upvotes: 29

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