What are some examples of using mocks in unit tests?

What are some examples of using mocks in unit tests?

Mocks are used in unit tests to simulate the behavior of complex objects. For example, if you have a function that makes an API call, you can use a mock to simulate the API response without actually hitting the endpoint.

Can you show me a code example of that?

Sure! Here's a simple example in Python using the unittest.mock library:

from unittest import mock
import requests

def fetch_data(url):
    response = requests.get(url)
    return response.json()

# Test function
@mock.patch('requests.get')
def test_fetch_data(mock_get):
    mock_get.return_value.json.return_value = {'key': 'value'}
    result = fetch_data('http://fakeurl.com')
    assert result == {'key': 'value'}

This mocks the requests.get method to return a predefined JSON response.

What are the benefits of using mocks in testing?

Using mocks helps isolate the unit of code being tested, making tests faster and more reliable. It also allows you to simulate various scenarios, such as error responses, without needing to rely on external systems.