Mocking external services in Django - Mini Project: Build & Apply

Mocking External Services in Django Tests

📖 Scenario: You are building a Django app that fetches weather data from an external API. To test your app without calling the real API every time, you will mock the external service.

🎯 Goal: Create a Django test that mocks an external weather API call to return fixed data, so tests run fast and reliably without internet.

📋 What You'll Learn

Create a function that calls an external weather API

Set up a test case in Django

Mock the external API call in the test

Verify the mocked data is used in the test

💡 Why This Matters

🌍 Real World

Mocking external services helps you test your Django apps quickly and reliably without depending on real APIs or internet connection.

💼 Career

Many jobs require writing tests that mock external APIs to ensure code quality and avoid flaky tests caused by network issues.

1

Create a function to fetch weather data

Create a function called get_weather(city) in a file named weather.py. This function should use the requests library to get JSON data from https://api.weather.com/v1/{city} and return the JSON response.

Django

# Your code here

Need a hint?

Use requests.get with an f-string URL and return response.json().

2

Set up a Django test case

Create a Django test case class called WeatherTestCase in tests.py. Import TestCase from django.test and the get_weather function from weather. Define a test method test_get_weather inside the class.

Django

import requests

def get_weather(city):
    response = requests.get(f'https://api.weather.com/v1/{city}')
    return response.json()

# Your code here

Need a hint?

Import TestCase and create a class with a test method stub.

3

Mock the external API call in the test

In the test_get_weather method, use unittest.mock.patch to mock requests.get. Make the mock return an object whose json() method returns {'temp': 20, 'condition': 'sunny'}. Call get_weather('London') and save the result in a variable called data.

Django

import requests
from django.test import TestCase
from weather import get_weather
from unittest.mock import patch, Mock

class WeatherTestCase(TestCase):
    def test_get_weather(self):
        # Your code here

Need a hint?

Use patch as a context manager to replace requests.get. Set mock_response.json.return_value to the fixed dictionary.

4

Verify the mocked data is used in the test

Add an assertion in test_get_weather to check that data['temp'] equals 20 and data['condition'] equals 'sunny'.

Django

import requests
from django.test import TestCase
from weather import get_weather
from unittest.mock import patch, Mock

class WeatherTestCase(TestCase):
    def test_get_weather(self):
        with patch('requests.get') as mock_get:
            mock_response = Mock()
            mock_response.json.return_value = {'temp': 20, 'condition': 'sunny'}
            mock_get.return_value = mock_response
            data = get_weather('London')
            # Your code here

Need a hint?

Use self.assertEqual to check the values in data.