Request and response validation in Testing Fundamentals - Build an Automation Script

Validate API request and response for user creation

Preconditions (2)

Step 1: Send a POST request to /users with JSON body {"name": "John Doe", "email": "[e-mail]"}

Step 2: Check the HTTP status code is 201

Step 3: Verify the response body contains the created user's id, name, and email

Step 4: Verify the response email matches the request email

✅ Expected Result: User is created successfully with status 201 and response body contains correct user data

Automation Requirements - Python requests with unittest

Assertions Needed:

Assert HTTP status code is 201

Assert response JSON has keys 'id', 'name', 'email'

Assert response 'email' equals request 'email'

Best Practices:

Use setup method to prepare test data

Use clear and descriptive assertion messages

Handle possible exceptions during request

Automated Solution

Testing Fundamentals

import unittest
import requests

class TestUserCreation(unittest.TestCase):
    def setUp(self):
        self.url = "https://api.example.com/users"
        self.user_data = {"name": "John Doe", "email": "[e-mail]"}

    def test_create_user(self):
        try:
            response = requests.post(self.url, json=self.user_data)
        except requests.exceptions.RequestException as e:
            self.fail(f"Request failed: {e}")

        self.assertEqual(response.status_code, 201, "Expected status code 201 for user creation")

        json_response = response.json()
        self.assertIn("id", json_response, "Response JSON should contain 'id'")
        self.assertIn("name", json_response, "Response JSON should contain 'name'")
        self.assertIn("email", json_response, "Response JSON should contain 'email'")

        self.assertEqual(json_response["email"], self.user_data["email"], "Response email should match request email")

if __name__ == "__main__":
    unittest.main()

The setUp method prepares the API URL and user data before each test.

The test method test_create_user sends a POST request with the user data JSON.

We catch exceptions to fail the test if the request fails.

Assertions check the HTTP status code is 201, meaning created successfully.

We verify the response JSON contains the keys id, name, and email.

Finally, we assert the email in the response matches the email sent in the request.

This ensures the API request and response are validated correctly.

Common Mistakes - 3 Pitfalls

Not checking the HTTP status code before parsing JSON

Hardcoding URLs or data inside the test method

Not handling exceptions from the request call

Bonus Challenge

Now add data-driven testing with 3 different user inputs to validate user creation for multiple cases

Show Hint

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