Integration testing in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this integration test response check?

Consider a REST API integration test that sends a GET request to /users/123. The test expects a JSON response with the user's name and status code 200.

What will be the printed output of this test snippet?

Rest API

response = client.get('/users/123')
if response.status_code == 200 and response.json().get('name') == 'Alice':
    print('Test Passed')
else:
    print('Test Failed')

A Test Failed

B Test Passed

C KeyError

D AttributeError

💡 Hint

Check if the response status and JSON content match the expected values.

The test checks if the status code is 200 and the JSON response contains the name 'Alice'. If both are true, it prints 'Test Passed'.

🧠 Conceptual

intermediate

Which component is typically NOT tested in integration testing of REST APIs?

Integration testing usually checks how different parts of a system work together. Which of these is least likely to be tested during REST API integration testing?

A Individual function logic inside a utility module

B API endpoint response format correctness

C Database interaction with API endpoints

D Authentication flow between client and server

💡 Hint

Think about what integration testing focuses on versus unit testing.

Integration testing focuses on how components interact, not on isolated function logic which is covered by unit tests.

🔧 Debug

advanced

Why does this integration test fail with a timeout error?

Given this integration test code snippet that calls an external API endpoint, why does it fail with a timeout error?

Rest API

response = client.get('/external-data', timeout=0.001)
print(response.status_code)

A The timeout value is too low causing the request to abort before response

B The endpoint URL is incorrect causing no response

C The client.get method does not support timeout parameter

D The response object does not have a status_code attribute

💡 Hint

Consider what happens if the timeout is set very low.

The timeout is set to 0.001 seconds, which is too short for the external API to respond, causing a timeout error.

📝 Syntax

advanced

Which option correctly mocks an API response in integration testing?

You want to mock a REST API response in your integration test using Python's unittest.mock. Which code snippet correctly mocks the client.get method to return a response with status code 200 and JSON {'success': true}?

A

with patch('client.get') as mock_get:
    mock_get.return_value = {'status_code': 200, 'json': {'success': True}}

B

with patch('client.get') as mock_get:
    mock_get.status_code = 200
    mock_get.json = {'success': True}

C

with patch('client.get') as mock_get:
    mock_get.return_value.status_code = 200
    mock_get.return_value.json = lambda: {'success': True}

D

with patch('client.get') as mock_get:
    mock_get.return_value.status_code = 200
    mock_get.return_value.json = {'success': True}

💡 Hint

Remember that json is a method, not a property.

Option C correctly sets return_value.status_code and mocks json as a lambda function returning the dictionary.

🚀 Application

expert

What is the number of items in the combined response after integration test aggregation?

An integration test calls two API endpoints: /products returning 3 items and /categories returning 2 items. The test aggregates both JSON lists into one list.

How many items will the combined list contain?

Rest API

products = client.get('/products').json()  # returns list of 3 items
categories = client.get('/categories').json()  # returns list of 2 items
combined = products + categories
print(len(combined))

A 2

B 6

C 3

D 5

💡 Hint

Think about how list concatenation works in Python.

Concatenating two lists of lengths 3 and 2 results in a list of length 5.

Practice

1. What is the main goal of integration testing in REST API development?

easy

A. To measure the speed of the server hardware

B. To test the user interface design

C. To check if different parts of the application work together correctly

D. To write documentation for the API

Solution

1. Step 1: Understand integration testing purpose

   Integration testing focuses on verifying that multiple components or services interact correctly.

2. Step 2: Compare options with integration testing goal

   Only To check if different parts of the application work together correctly describes checking the cooperation of different parts, which matches integration testing.

3. Final Answer:

   To check if different parts of the application work together correctly -> Option C

4. Quick Check:

   Integration testing = check parts work together [OK]

Hint: Integration tests check connections between parts, not UI or speed [OK]

Common Mistakes:

• Confusing integration testing with UI testing
• Thinking integration tests measure performance
• Believing integration tests are for documentation

2. Which of the following is the correct way to send a GET request in a Python integration test using the requests library?

easy

A. response = requests.get('http://api.example.com/data')

B. response = requests.post('http://api.example.com/data')

C. response = requests.fetch('http://api.example.com/data')

D. response = requests.send('http://api.example.com/data')

Solution

1. Step 1: Recall correct method for GET request in requests library

   The method to send a GET request is requests.get().

2. Step 2: Check options for correct syntax

   Only response = requests.get('http://api.example.com/data') uses requests.get() correctly with a URL string.

3. Final Answer:

   response = requests.get('http://api.example.com/data') -> Option A

4. Quick Check:

   GET request method = requests.get() [OK]

Hint: Use requests.get() for GET requests, not post, fetch, or send [OK]

Common Mistakes:

• Using requests.post() instead of get() for GET requests
• Using non-existent methods like fetch() or send()
• Missing quotes around the URL string

3. Consider this Python integration test snippet using requests:

response = requests.post('http://api.example.com/login', json={'user':'admin', 'pass':'1234'})
print(response.status_code)

What will be the printed output if the login is successful and the server returns HTTP 200?

medium

A. 200

B. 403

C. 500

D. 404

Solution

1. Step 1: Understand HTTP status codes

   HTTP 200 means success, 404 means not found, 500 means server error, 403 means forbidden.

2. Step 2: Analyze the code output

   The code prints response.status_code. If login is successful, server returns 200, so output is 200.

3. Final Answer:

   200 -> Option A

4. Quick Check:

   Success status code = 200 [OK]

Hint: Successful HTTP response status is 200 [OK]

Common Mistakes:

• Confusing 404 (not found) with success
• Assuming 500 means success
• Mixing 403 (forbidden) with success

4. You wrote this integration test code:

response = requests.get('http://api.example.com/items')
assert response.status_code == 200
assert response.json()['items']

But the test fails with a KeyError on 'items'. What is the likely cause?

medium

A. The URL is incorrect and returns 404

B. The requests library is not imported

C. The status code is not 200

D. The response JSON does not contain the key 'items'

Solution

1. Step 1: Understand KeyError cause

   A KeyError means the key 'items' is missing in the JSON response.

2. Step 2: Analyze test failure reason

   Since status code is asserted as 200, the URL is likely correct and requests imported. The error is missing 'items' key in JSON.

3. Final Answer:

   The response JSON does not contain the key 'items' -> Option D

4. Quick Check:

   KeyError means missing key in JSON [OK]

Hint: KeyError means JSON key missing, not URL or import error [OK]

Common Mistakes:

• Assuming URL is wrong without checking status code
• Ignoring that status code 200 means request succeeded
• Forgetting to import requests library

5. You want to write an integration test that verifies your REST API endpoint /users returns only active users. The API returns JSON like {"users": [{"id":1,"active":true}, {"id":2,"active":false}]}. Which test code snippet correctly checks this condition?

hard

A. response = requests.get('http://api.example.com/users')
users = response.json()['users']
assert any(user['active'] for user in users)

B. response = requests.get('http://api.example.com/users')
users = response.json()['users']
assert all(user['active'] for user in users)

C. response = requests.get('http://api.example.com/users')
users = response.json()['users']
assert user['active'] == True

D. response = requests.get('http://api.example.com/users')
assert response.status_code == 404

Solution

1. Step 1: Understand requirement to check all users are active

   The test must confirm every user in the list has active set to true.

2. Step 2: Analyze code snippets for correctness

   response = requests.get('http://api.example.com/users') users = response.json()['users'] assert all(user['active'] for user in users) uses all() to check all users are active, which matches requirement. response = requests.get('http://api.example.com/users') users = response.json()['users'] assert any(user['active'] for user in users) checks if any user is active (not enough). response = requests.get('http://api.example.com/users') users = response.json()['users'] assert user['active'] == True references undefined variable user outside loop. response = requests.get('http://api.example.com/users') assert response.status_code == 404 checks for 404 status, which is wrong.

3. Final Answer:

   response = requests.get('http://api.example.com/users') users = response.json()['users'] assert all(user['active'] for user in users) -> Option B

4. Quick Check:

   Use all() to verify all users active [OK]

Hint: Use all() to confirm every user is active [OK]

Common Mistakes:

• Using any() instead of all() to check all users
• Referencing undefined variables in assertions
• Checking wrong HTTP status code