Python MagicMock.return_value returning MagicMock instead of return_value

Question

I have a function that verifies if a given input string is a proper GCP zone:

def validate_zone(compute, project_id, zone):
    try:
        zone_response = compute.zones().get(project=project_id, zone=zone).execute()
        print(zone_response)
        print(zone_response.return_value)
        if ['status'] in zone_response:
            zone_details = {
                'status': zone_response['status'],
                'region': zone_response['region'],
                'name': zone_response['name']
            }
            return zone_details
        else:
            return "Zone {} not found for project {}".format(zone, project_id)
    except HttpError as error:
        print("Error calling zone {}: \n {}".format(zone, error))

I am trying to write a test to verify that but I can't mock the output of the compute method correctly.

@patch('googleapiclient.discovery')
def test_validate_zone(self, mock_response):
    compute = mock_response.build(serviceName='compute', version='v1')
    compute.zones().get(project_id=self.project_id, zone=self.zone).execute().return_value = {
        'status': 'status',
        'region': 'region',
        'name': 'name'
    }
    zone_response = inventory.validate_zone(compute, self.project_id, self.zone)
    print(zone_response)

This results in the zone_response output being a MagicMock object with its return_value being correct as developed in the test.

zone_response = MagicMock name='discovery.build().zones().get().execute()' id='139870134525456'

zone_response.return_value = {'status': 'status', 'region': 'region', 'name': 'name'}

Any ideas on what I'm doing wrong? I've been trying to write tests for this for quite a while so maybe my approach is just off.

Answer 1

Turns out the issue was the () on the execute method in the test. So the correct test should be:

@patch('inventory.discovery.build', serviceName='compute', version='v1')
    def test_validate_zone(self, compute):
        print(compute)
        compute.zones().get(project_id=self.project_id, zone=self.zone).execute.return_value = {
            'status': 'status',
            'region': 'region',
            'name': 'name'
        }
        zone_response = inventory.validate_zone(compute, self.project_id, self.zone)
        print(zone_response)

Source can be found at: https://realpython.com/python-mock-library/#managing-a-mocks-return-value