Mocking Requests and Responses for Python Testing

In Python testing, it becomes necessary to mock modules and their functionality to control the flow of execution and verify specific scenarios. Among these, mocking the requests module is commonly used to test functions or methods that rely on HTTP requests.

Consider a views.py file with the following code:

def myview(request):
    res1 = requests.get('aurl')
    res2 = request.get('burl')
    res3 = request.get('curl')

To mock this behavior, you can employ the Python mock package. Here's how you can achieve it step by step:

Step 1: Define the Mock Behavior

To mock the requests module, define a function that will substitute requests.get(). In this function, you can specify the desired response for each URL.

def mocked_requests_get(*args, **kwargs):
    class MockResponse:
        def __init__(self, json_data, status_code):
            self.json_data = json_data
            self.status_code = status_code

        def json(self):
            return self.json_data

    if args[0] == 'aurl':
        return MockResponse({'a': 'a'}, 200)
    elif args[0] == 'burl':
        return MockResponse({'b': 'b'}, 200)
    elif args[0] == 'curl':
        return MockResponse({'c': 'c'}, 200)

    return MockResponse(None, 404)

Step 2: Patch the Requests Module

In your test case, use the mock.patch() decorator to replace the actual requests module with your mock function.

@mock.patch('requests.get', side_effect=mocked_requests_get)
def test_myview(self, mock_get):
    # Call the function you want to test
    myview(None)
    # Assertions for expected responses
    ...

Step 3: Verify Assertions

Within your test function, you can use assertions to verify that the expected responses are returned.

self.assertEqual(mock_get.call_args_list[0][0][0], 'aurl')
self.assertEqual(mock_get.call_args_list[1][0][0], 'burl')
self.assertEqual(mock_get.call_args_list[2][0][0], 'curl')

By following these steps, you can effectively mock HTTP requests and control the responses in your Python testing scenarios. This allows you to isolate and test specific functionality while ensuring that external dependencies do not interfere with your results.