Contract testing basics in Testing Fundamentals - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a contract test that checks the provider's response status.

Testing Fundamentals

def test_provider_response():
    response = provider.get_data()
    assert response.status_code == [1]

Drag options to blanks, or click blank then click option'

A200

B404

C500

D302

Attempts:

3 left

💡 Hint

Common Mistakes

Using 404 which means 'Not Found' instead of 200.

Using 500 which means server error.

The HTTP status code 200 means the request was successful, which is expected in a contract test for a valid response.

2fill in blank

medium

Complete the code to verify the provider returns the expected JSON key in the contract test.

Testing Fundamentals

def test_provider_data_keys():
    data = provider.get_data().json()
    assert '[1]' in data

Drag options to blanks, or click blank then click option'

Astatus

Berror

CuserId

Dmessage

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for 'error' key which is for error responses.

Using 'message' which is usually for status messages.

The contract expects the provider to return a JSON with the key userId, which identifies the user data.

3fill in blank

hard

Fix the error in the assertion to correctly check the provider's response content type.

Testing Fundamentals

def test_content_type():
    response = provider.get_data()
    assert response.headers['Content-Type'] == [1]

Drag options to blanks, or click blank then click option'

A'application/xml'

B'text/html'

C'multipart/form-data'

D'application/json'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'text/html' which is for web pages.

Using 'application/xml' which is for XML data.

The contract requires the provider to return JSON data, so the content type must be application/json.

4fill in blank

hard

Fill both blanks to create a contract test that checks the provider's response time and status code.

Testing Fundamentals

def test_response_time_and_status():
    response = provider.get_data()
    assert response.elapsed.total_seconds() [1] 1.0
    assert response.status_code [2] 200

Drag options to blanks, or click blank then click option'

A<

B==

C!=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' for response time which would allow slow responses.

Using '!=' for status code which would accept errors.

The test checks that the response time is less than 1 second and the status code equals 200, ensuring performance and correctness.

5fill in blank

hard

Fill all three blanks to write a contract test that verifies the provider's JSON response structure.

Testing Fundamentals

def test_json_structure():
    data = provider.get_data().json()
    assert isinstance(data, [1])
    assert '[2]' in data
    assert isinstance(data['[2]'], [3])

Drag options to blanks, or click blank then click option'

Adict

Buser

Clist

Dstr

Attempts:

3 left

💡 Hint

Common Mistakes

Assuming the top-level JSON is a list instead of a dictionary.

Checking for a key other than 'user'.

Expecting the 'user' value to be a string instead of a dictionary.

The response should be a dictionary containing a key 'user', which itself is a dictionary representing user details.

Practice

1. What is the main purpose of contract testing in software development?

easy

A. To ensure two systems agree on the format and data of their communication

B. To test the user interface for visual bugs

C. To check the performance speed of an application

D. To verify database schema changes

Solution

1. Step 1: Understand contract testing definition

   Contract testing focuses on the agreement between two systems on how they communicate, including request and response formats.

2. Step 2: Compare options with contract testing purpose

   Only To ensure two systems agree on the format and data of their communication describes this agreement on communication format and data, which is the core of contract testing.

3. Final Answer:

   To ensure two systems agree on the format and data of their communication -> Option A

4. Quick Check:

   Contract testing = communication agreement [OK]

Hint: Contract testing checks communication agreements between systems [OK]

Common Mistakes:

• Confusing contract testing with UI testing
• Thinking contract testing measures performance
• Assuming contract testing checks database structure

2. Which of the following is the correct way to describe a contract in contract testing?

easy

A. A set of UI elements and their styles

B. A list of database tables and columns

C. A defined request and expected response between services

D. A performance benchmark for API calls

Solution

1. Step 1: Identify what a contract defines

   A contract in contract testing defines the request sent and the expected response received between two services.

2. Step 2: Match options to contract definition

   A defined request and expected response between services correctly describes this request-response definition, while others describe unrelated concepts.

3. Final Answer:

   A defined request and expected response between services -> Option C

4. Quick Check:

   Contract = request + expected response [OK]

Hint: Contracts define requests and expected responses [OK]

Common Mistakes:

• Mixing contracts with UI or database details
• Thinking contracts are about performance
• Confusing contracts with test cases

3. Given a contract test that expects a JSON response with a field status equal to "success", what will happen if the actual response is {"status": "fail"}?

medium

A. The test will pass because the response is JSON

B. The test will fail because the status value does not match

C. The test will pass because the field status exists

D. The test will fail due to a syntax error in the response

Solution

1. Step 1: Understand the contract expectation

   The contract expects the status field to have the value "success" exactly.

2. Step 2: Compare actual response to expected

   The actual response has "status": "fail", which does not match the expected value, causing the test to fail.

3. Final Answer:

   The test will fail because the status value does not match -> Option B

4. Quick Check:

   Expected value mismatch = test fail [OK]

Hint: Exact value mismatch causes contract test failure [OK]

Common Mistakes:

• Assuming presence of field is enough to pass
• Ignoring value differences in contract tests
• Confusing syntax errors with value mismatches

4. You wrote a contract test but it always passes even when the provider sends incorrect data. What is the most likely mistake?

medium

A. The contract test has syntax errors and does not run

B. The contract test is missing the request URL

C. The contract test is running on the wrong environment

D. The contract test is not validating the response content properly

Solution

1. Step 1: Analyze why test passes despite incorrect data

   If the test passes even with wrong data, it likely means the test is not checking the response content correctly.

2. Step 2: Evaluate other options

   Missing URL or wrong environment would cause errors or failures, and syntax errors prevent running, so these are less likely.

3. Final Answer:

   The contract test is not validating the response content properly -> Option D

4. Quick Check:

   Incorrect validation = false pass [OK]

Hint: Check if test actually validates response content [OK]

Common Mistakes:

• Ignoring validation logic in tests
• Assuming environment issues cause false passes
• Confusing syntax errors with test logic errors

5. You have two microservices: Service A (consumer) and Service B (provider). Service A expects Service B to return a JSON with a userId as a number and active as a boolean. Which contract test scenario best ensures compatibility?

hard

A. Test that Service B returns {"userId": 123, "active": true} and reject if types differ

B. Test that Service B returns any JSON object with keys userId and active regardless of types

C. Test that Service B returns a string containing userId and active anywhere

D. Test that Service B returns a JSON with userId as string and active as number

Solution

1. Step 1: Identify expected data types in contract

   Service A expects userId as a number and active as a boolean, so the contract must enforce these types.

2. Step 2: Evaluate options for strictness and correctness

   Test that Service B returns {"userId": 123, "active": true} and reject if types differ tests exact types and values, ensuring compatibility. Options A, B, and C ignore or mismatch types, risking integration errors.

3. Final Answer:

   Test that Service B returns {"userId": 123, "active": true} and reject if types differ -> Option A

4. Quick Check:

   Strict type check = compatibility ensured [OK]

Hint: Contract tests must check exact data types and values [OK]

Common Mistakes:

• Ignoring data types in contract tests
• Accepting any JSON structure without validation
• Confusing string and number types in contracts