Stubber not intercepting

When using a client created outside of the test, calls are made to an actual client. Given the following code and tests:

def create_client(service):
    return boto3.client(service, config=CLIENT_CONFIG)

def get_security_group_data(filters):
    client = create_client('ec2')
    return client.describe_security_groups(Filters=filters)

def test_get_security_group_data():
    import boto3
    from botocore.stub import Stubber
    ec2_client = boto3.client('ec2', region_name='us-west-2')
    filters = [
            {
                'FilterName': 'tag:Name',
                'FilterValues': [
                    'Default'
                ]
            }
        ]

        describe_security_groups_response = {
            'SecurityGroups': [
                {
                    'GroupName': 'Default',
                    'GroupId': 'sg-1234abc',
                    'VpcId': 'vpc-12345ab',
                    'Tags': [
                        {
                            'Key': 'Name',
                            'Value': 'Default'
                        },
                    ],
                }
            ]
        }
    stubber = Stubber(ec2_client)
    stubber.add_response('describe_security_groups', describe_security_groups_response,
                         {'Filters': filters})
    stubber.activate()
    response_data = get_security_group_data(filters)

The following is raised during the test:

security_group.py:18: in get_security_group_data
    client = create_client('ec2')
functions.py:7: in create_client
    return boto3.client(service, config=CLIENT_CONFIG)
.env/lib/python3.7/site-packages/boto3/__init__.py:91: in client
    return _get_default_session().client(*args, **kwargs)
.env/lib/python3.7/site-packages/boto3/session.py:263: in client
    aws_session_token=aws_session_token, config=config)
.env/lib/python3.7/site-packages/botocore/session.py:839: in create_client
    client_config=config, api_version=api_version)
.env/lib/python3.7/site-packages/botocore/client.py:86: in create_client
    verify, credentials, scoped_config, client_config, endpoint_bridge)
.env/lib/python3.7/site-packages/botocore/client.py:328: in _get_client_args
    verify, credentials, scoped_config, client_config, endpoint_bridge)
.env/lib/python3.7/site-packages/botocore/args.py:47: in get_client_args
    endpoint_url, is_secure, scoped_config)
.env/lib/python3.7/site-packages/botocore/args.py:117: in compute_client_args
    service_name, region_name, endpoint_url, is_secure)
.env/lib/python3.7/site-packages/botocore/client.py:402: in resolve
    service_name, region_name)
.env/lib/python3.7/site-packages/botocore/regions.py:122: in construct_endpoint
    partition, service_name, region_name)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <botocore.regions.EndpointResolver object at 0x7ff86a4c9208>
partition = OrderedDict([('defaults', OrderedDict([('hostname', '{service}.{region}.{dnsSuffix}'), ('protocols', ['https']), ('sig...1', OrderedDict()), ('us-east-2', OrderedDict()), ('us-west-1', OrderedDict()), ('us-west-2', OrderedDict())]))]))]))])
service_name = 'ec2', region_name = None

    def _endpoint_for_partition(self, partition, service_name, region_name):
        # Get the service from the partition, or an empty template.
        service_data = partition['services'].get(
            service_name, DEFAULT_SERVICE_DATA)
        # Use the partition endpoint if no region is supplied.
        if region_name is None:
            if 'partitionEndpoint' in service_data:
                region_name = service_data['partitionEndpoint']
            else:
>               raise NoRegionError()
E               botocore.exceptions.NoRegionError: You must specify a region.

.env/lib/python3.7/site-packages/botocore/regions.py:135: NoRegionError
------------------------------------------------------------ Captured log call ------------------------------------------------------------
INFO     botocore.credentials:credentials.py:1093 Found credentials in shared credentials file: ~/.aws/credentials

[tim-finnigan]

Hi @mcaulifn, I can bring this up with our doc writers and see if there are better examples we could add.

I saw you were using SNS in an earlier post. This other code samples page may provide more relevant examples for your use case: https://docs.aws.amazon.com/code-samples/latest/catalog/python-sns-test-test_sns_basics.py.html

[mcaulifn]

@tim-finnigan The existing documentation is not very helpful as it shows code within a test file rather than in a module or package. Can you update the docs to show a better real world type example?