Testing API endpoints in Django - Mini Project: Build & Apply

Testing API endpoints

📖 Scenario: You are building a simple Django API for a bookstore. You want to make sure your API endpoints work correctly by writing tests.

🎯 Goal: Write tests for the API endpoints to check that the responses return the expected status codes and data.

📋 What You'll Learn

Create a test client to send requests to the API

Write a test to check the GET request to the book list endpoint

Write a test to check the POST request to add a new book

Verify the response status codes and returned data in tests

💡 Why This Matters

🌍 Real World

Testing API endpoints ensures your web services work correctly and reliably before users interact with them.

💼 Career

API testing is a key skill for backend developers and QA engineers to maintain quality and prevent bugs in web applications.

1

Set up test data

Create a list called books with two dictionaries representing books. Each dictionary should have 'title' and 'author' keys with these exact values: {'title': 'Django for Beginners', 'author': 'William S. Vincent'} and {'title': 'Two Scoops of Django', 'author': 'Daniel Roy Greenfeld'}.

Django

# Your code here

Hint

Use a list with two dictionaries exactly as shown.

2

Configure the test client

Import APIClient from rest_framework.test and create a variable called client that is an instance of APIClient().

Django

books = [
    {'title': 'Django for Beginners', 'author': 'William S. Vincent'},
    {'title': 'Two Scoops of Django', 'author': 'Daniel Roy Greenfeld'}
]

# Your code here

Hint

Import APIClient and create client = APIClient().

3

Write a test for GET /books/

Write a function called test_get_books() that uses client.get to request the '/books/' endpoint. Inside the function, assign the response to a variable called response. Then check that response.status_code equals 200 and that response.data equals the books list.

Django

from rest_framework.test import APIClient

books = [
    {'title': 'Django for Beginners', 'author': 'William S. Vincent'},
    {'title': 'Two Scoops of Django', 'author': 'Daniel Roy Greenfeld'}
]

client = APIClient()

# Your code here

Hint

Define test_get_books(), call client.get('/books/'), and assert status code and data.

4

Write a test for POST /books/

Write a function called test_post_book() that uses client.post to send a new book dictionary {'title': 'Effective Django', 'author': 'Brett Slatkin'} to the '/books/' endpoint with format='json'. Assign the response to response. Then check that response.status_code equals 201 and that response.data contains the new book dictionary.

Django

from rest_framework.test import APIClient

books = [
    {'title': 'Django for Beginners', 'author': 'William S. Vincent'},
    {'title': 'Two Scoops of Django', 'author': 'Daniel Roy Greenfeld'}
]

client = APIClient()

def test_get_books():
    response = client.get('/books/')
    assert response.status_code == 200
    assert response.data == books

# Your code here

Hint

Define test_post_book(), post the new book with format='json', and assert status code and data.

Practice

1. What is the main purpose of using Django REST Framework's APIClient in testing?

easy

A. To simulate API requests and check responses

B. To create database migrations automatically

C. To generate HTML templates for views

D. To manage user authentication in the admin panel

Solution

1. Step 1: Understand the role of APIClient

   APIClient is designed to simulate HTTP requests to API endpoints in tests.

2. Step 2: Identify its testing purpose

   It helps verify that the API sends correct responses to requests.

3. Final Answer:

   To simulate API requests and check responses -> Option A

4. Quick Check:

   APIClient simulates API calls [OK]

Hint: APIClient is for simulating API calls in tests [OK]

Common Mistakes:

• Confusing APIClient with database migration tools
• Thinking APIClient generates HTML templates
• Assuming APIClient manages admin authentication

2. Which of the following is the correct way to import APIClient for testing in Django REST Framework?

easy

A. from django.test import APIClient

B. from rest_framework.test import APIClient

C. import APIClient from rest_framework

D. from rest_framework.client import APIClient

Solution

1. Step 1: Recall the correct import path

   APIClient is part of rest_framework.test module.

2. Step 2: Match the correct syntax

   The correct import is from rest_framework.test import APIClient.

3. Final Answer:

   from rest_framework.test import APIClient -> Option B

4. Quick Check:

   Correct import path [OK]

Hint: APIClient is in rest_framework.test module [OK]

Common Mistakes:

• Importing APIClient from django.test instead
• Using incorrect import syntax like 'import APIClient from ...'
• Confusing module rest_framework.client with rest_framework.test

3. Given the following test code snippet, what will be the status code of the response if the endpoint exists and returns data successfully?

client = APIClient()
response = client.get('/api/items/')
print(response.status_code)

medium

A. 404

B. 302

C. 200

D. 500

Solution

1. Step 1: Understand the GET request behavior

   A successful GET request to an existing API endpoint returns status code 200.

2. Step 2: Identify the expected status code

   Since the endpoint exists and returns data, the status code will be 200.

3. Final Answer:

   200 -> Option C

4. Quick Check:

   Successful GET response = 200 [OK]

Hint: Successful GET requests return 200 status code [OK]

Common Mistakes:

• Confusing 404 (not found) with success
• Assuming 500 means success
• Thinking 302 redirect is default for API GET

4. Identify the error in this test code snippet that causes the test to fail:

client = APIClient()
response = client.post('/api/items/', data={'name': 'Book'})
self.assertEqual(response.status_code, 201)

medium

A. Missing format='json' in the post request

B. Using post instead of get for data retrieval

C. Incorrect URL path format

D. Not importing APIClient before use

Solution

1. Step 1: Check POST request data format

   By default, APIClient sends data as form-encoded unless format='json' is specified.

2. Step 2: Understand why test fails

   The API expects JSON data, so missing format='json' causes the server to reject or misinterpret data, failing the test.

3. Final Answer:

   Missing format='json' in the post request -> Option A

4. Quick Check:

   POST JSON data needs format='json' [OK]

Hint: Add format='json' when posting JSON data [OK]

Common Mistakes:

• Assuming POST sends JSON by default
• Confusing GET and POST methods
• Ignoring import statements

5. You want to test an API endpoint that requires authentication. Which sequence correctly tests a protected GET endpoint using Django REST Framework's APIClient?

hard

A. Call client.get() first, then authenticate client with credentials

B. Set authentication headers manually without using client methods

C. Use client.post() without authentication to access the endpoint

D. Authenticate client with credentials, then call client.get() on the endpoint

Solution

1. Step 1: Authenticate the APIClient before requests

   Use client.force_authenticate(user=user) or set credentials before making requests.

2. Step 2: Make the GET request after authentication

   Once authenticated, call client.get() to access the protected endpoint successfully.

3. Final Answer:

   Authenticate client with credentials, then call client.get() on the endpoint -> Option D

4. Quick Check:

   Authenticate before GET request [OK]

Hint: Authenticate client before calling protected endpoint [OK]

Common Mistakes:

• Calling GET before authentication
• Using POST instead of GET for retrieval
• Manually setting headers incorrectly