CODEWITHSUNDEEP
python
princesingh
princesingh

Reputation: 35

How to test a decorator?

I am new to unit testing. can anyone guide me to test this decorator with mock and patch

 def fetch_entity_from_ES(self,func):
    @wraps(func)
    def ES_wrapper(*args):
        entity_type = args[0]
        entity_id = args[1]
        search_service_utility = ElasticSearchUtilities(self.config)
        entity = search_service_utility.fetch_entity_from_ES(entity_type, entity_id)
        if not entity:
            return func(*args)
        return entity
    return ES_wrapper

Upvotes: 1

Views: 94

Answers (1)

Aaron Bentley
Aaron Bentley

Reputation: 1380

You can test decorators by applying them to a test function. You then run the decorated function and check the behavior.

In this case, the decorated function is an inner function, so it has access to the test method's self etc, if needed.

class TestFetchEntityFromES(TestCase):

    def test_fetch_entity_from_ES(self):

        @fetch_entity_from_ES
        def foo(entity_type, entity_id):
            return 'bar'

        with patch.object(ElasticSearchUtilities, 'fetch_entity_from_ES',
                          return_value=None):
            self.assertEqual(foo('type1', 'id1'), 'bar')
        with patch.object(ElasticSearchUtilities, 'fetch_entity_from_ES',
                          return_value='baz'):
            self.assertEqual(foo('type1', 'id1'), 'baz')

BTW, fetch_entity_from_ES looks like a method because it has a self parameter, but I've treated it as a function.

Upvotes: 1

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