how to patch boto3 lambda invoke on unit test

Question

I want to add a patch annotation to a unit test so that when my boto3 lambda client tries to invoke instead we will get a mock response, but when i try add the patch to my unit test it get the following error AttributeError: <function client at 0x106a38b80> does not have the attribute 'invoke'

Here is the attempted test

    @patch("functions.my_function.my_function.boto3.client.invoke")
    def test_duck_response_200(self, lambda_mock_response):
        mock_response = Mock()
        mock_response.status_code = 200
        mock_response.content = get_response()
        
        lambda_mock_response.return_value = mock_response
        
        id = "111111111"

        response = invoke_lambda(id)

Here is the function

lambda_client = boto3.client("lambda", region)

def invoke_lambda(id):
    payload = {"id": id}

    response = lambda_client.invoke(
        FunctionName=os.environ["MY_LAMBDA"],
        Payload=json.dumps(payload),
    )
    response_content = json.loads(response["Payload"].read().decode())
    return response_content["claim"][0]

Answer 1

lets say your invoke_lambda is in my_lambda.py file. You want to use the patch annotation to mock the lambda_client, not the response. You can then set the return_value of the mocked_lambda_client to mocked_response .

# my_lambda.py
def get_attachment(my_id):
    payload = {"myId": my_id}
    response = lambda_client.invoke(
        FunctionName=os.environ["MY_LAMBDA"],
        Payload=json.dumps(payload),
    )
    return response.status_code

# test_my_lambda.py
@mock.patch("my_lambda.lambda_client")
def test_duck_response_200(mock_lambda_client):
    mocked_response = mock.Mock()
    mocked_response.status_code = 200

    mock_lambda_client.invoke.return_value = mocked_response
    response = get_attachment('some_id')
    assert response == 200