Request and response validation in Testing Fundamentals - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this API response validation code?

Consider this Python code snippet that validates an API JSON response status and content:

response = {'status_code': 200, 'data': {'user': 'alice', 'id': 123}}

assert response['status_code'] == 200
assert 'user' in response['data']
print('Validation passed')

What will be printed when this code runs?

Testing Fundamentals

response = {'status_code': 200, 'data': {'user': 'alice', 'id': 123}}

assert response['status_code'] == 200
assert 'user' in response['data']
print('Validation passed')

A KeyError

B AssertionError

C TypeError

D Validation passed

💡 Hint

Check if the status code is 200 and if the key 'user' exists in the nested data dictionary.

The response has status_code 200 and the 'user' key is present in the 'data' dictionary, so both assertions pass and 'Validation passed' is printed.

❓ assertion

intermediate

Which assertion correctly checks the response contains a non-empty 'items' list?

You receive this JSON response from an API:

{'status': 'success', 'items': [1, 2, 3]}

Which assertion statement correctly verifies that 'items' exists and is not empty?

A assert response['items'] != None

B assert 'items' in response and len(response['items']) > 0

C assert response['items'] is not []

D assert response['items']

💡 Hint

Check both the presence of the key and that the list has elements.

Option B explicitly checks the key exists and the list length is greater than zero, ensuring 'items' is present and non-empty.

Option B only checks not None but key might be missing.

Option B compares list identity which is unreliable.

Option B passes if list is truthy but fails if key missing.

🔧 Debug

advanced

Why does this request validation test fail with a KeyError?

Given this test code snippet:

request = {'method': 'POST', 'body': {'username': 'bob'}}
assert request['body']['password'] == 'secret'

Why does this test raise a KeyError?

Testing Fundamentals

request = {'method': 'POST', 'body': {'username': 'bob'}}
assert request['body']['password'] == 'secret'

A The 'password' key does not exist in the 'body' dictionary, causing KeyError

B The 'body' key is missing in the request dictionary

C The 'method' key is not 'POST', causing assertion failure

D The 'password' value is None, causing TypeError

💡 Hint

Check if the key you access exists in the dictionary.

The 'body' dictionary has only 'username' key. Accessing 'password' key raises KeyError because it is missing.

🧠 Conceptual

advanced

What is the main purpose of response schema validation in API testing?

Why do testers perform response schema validation when testing APIs?

A To ensure the response structure and data types match the expected format

B To check if the API server is running and reachable

C To verify the response time is under a threshold

D To confirm the API request headers are correctly set

💡 Hint

Think about what schema means in data context.

Response schema validation checks that the response JSON has the correct keys, nested structure, and data types as expected.

❓ framework

expert

Which test framework feature best supports automated request and response validation?

In automated API testing, which feature of a test framework helps validate both request payloads and response data effectively?

A Static code analysis tools for syntax checking

B Manual test case execution with screenshots

C Data-driven testing with parameterized test cases

D Version control integration for code commits

💡 Hint

Consider how to run the same test with many input and output variations automatically.

Data-driven testing allows running the same test logic with multiple sets of request and expected response data, automating validation efficiently.

Practice

1. What is the main purpose of request and response validation in software testing?

easy

A. To write code faster

B. To check if the data sent and received matches expected formats and values

C. To design the user interface

D. To improve the speed of the application

Solution

1. Step 1: Understand the role of validation

   Request and response validation ensures the data sent and received is correct and follows expected rules.

2. Step 2: Identify the main goal

   This process helps catch errors early by verifying data formats and values before further processing.

3. Final Answer:

   To check if the data sent and received matches expected formats and values -> Option B

4. Quick Check:

   Validation = Check data correctness [OK]

Hint: Validation means checking data correctness both ways [OK]

Common Mistakes:

• Confusing validation with performance testing
• Thinking validation changes UI design
• Assuming validation speeds up coding

2. Which of the following is the correct way to assert that a response status code is 200 in a test script?

easy

A. assert response.code = 200

B. assert response.status == '200'

C. assert response.status_code = '200'

D. assert response.status_code == 200

Solution

1. Step 1: Check correct attribute and comparison

   The correct attribute for HTTP status code is status_code and it should be compared with == for equality.

2. Step 2: Identify correct syntax

   assert response.status_code == 200 uses assert response.status_code == 200, which is syntactically correct and logically valid.

3. Final Answer:

   assert response.status_code == 200 -> Option D

4. Quick Check:

   Use == to compare status_code with integer 200 [OK]

Hint: Use == to compare status_code with integer 200 [OK]

Common Mistakes:

• Using single = instead of == for comparison
• Comparing status_code to string '200' instead of integer
• Using wrong attribute names like status or code

3. Given this test code snippet:

response = api_call()
assert response.json()['success'] == True
assert response.status_code == 201

What will happen if the API returns status code 200 and success is True?

medium

A. Test will fail on the status code assertion

B. Test will pass successfully

C. Test will fail on the success key assertion

D. Test will raise a syntax error

Solution

1. Step 1: Check success key assertion

   The assertion response.json()['success'] == True will pass because success is True.

2. Step 2: Check status code assertion

   The assertion response.status_code == 201 will fail because the actual status code is 200, not 201.

3. Final Answer:

   Test will fail on the status code assertion -> Option A

4. Quick Check:

   Status code 200 != 201 causes failure [OK]

Hint: Check each assertion separately for pass/fail [OK]

Common Mistakes:

• Assuming test passes if one assertion passes
• Confusing status code 200 with 201
• Thinking syntax error occurs when assertions fail

4. You have this test code:

assert response.json()['data'] != None

But the test fails with a KeyError. What is the most likely cause?

medium

A. The 'data' key does not exist in the response JSON

B. The response is not JSON format

C. The assertion syntax is incorrect

D. The response status code is not 200

Solution

1. Step 1: Understand KeyError cause

   A KeyError happens when trying to access a dictionary key that does not exist.

2. Step 2: Analyze the assertion

   The assertion accesses response.json()['data']. If 'data' key is missing, KeyError occurs.

3. Final Answer:

   The 'data' key does not exist in the response JSON -> Option A

4. Quick Check:

   Missing key causes KeyError [OK]

Hint: KeyError means missing key in dictionary [OK]

Common Mistakes:

• Assuming assertion syntax error causes KeyError
• Thinking response format causes KeyError without checking keys
• Ignoring that missing keys cause KeyError

5. You want to validate a JSON response that may or may not include the key error. Which assertion correctly checks that if error exists, its value is a non-empty string?

hard

A. assert response.json()['error'] != ''

B. assert response.json().get('error') == ''

C. assert 'error' not in response.json() or (isinstance(response.json()['error'], str) and response.json()['error'] != '')

D. assert 'error' in response.json() and response.json()['error'] == ''

Solution

1. Step 1: Understand conditional validation

   The assertion must allow the 'error' key to be missing or, if present, check its value is a non-empty string.

2. Step 2: Analyze each option

   assert 'error' not in response.json() or (isinstance(response.json()['error'], str) and response.json()['error'] != '') uses logical OR: if 'error' not present, passes; else checks type and non-empty string. Other options fail if 'error' is missing or check wrong conditions.

3. Final Answer:

   assert 'error' not in response.json() or (isinstance(response.json()['error'], str) and response.json()['error'] != '') -> Option C

4. Quick Check:

   Allow missing key or validate non-empty string [OK]

Hint: Use OR to allow missing key or validate value [OK]

Common Mistakes:

• Assuming key always exists without checking
• Checking for empty string instead of non-empty
• Using incorrect logical operators