Integration testing in Testing Fundamentals - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of Integration Testing

What is the main purpose of integration testing in software development?

A To validate the user interface design and usability

B To verify that individual units or components work correctly in isolation

C To test the software's performance under heavy load

D To check that different modules or services work together as expected

💡 Hint

Think about what happens after individual parts are tested separately.

Integration testing focuses on checking if different parts of the software interact correctly, ensuring combined functionality works as intended.

❓ Predict Output

intermediate

Integration Test Result Interpretation

Given the following integration test code snippet, what will be the output after running the test?

Testing Fundamentals

def service_a():
    return 5

def service_b(x):
    return x * 2

result = service_b(service_a())
print(result)

A 10

B 5

C TypeError

D None

💡 Hint

Calculate the output step-by-step: service_a returns a value, then service_b uses it.

service_a returns 5, service_b multiplies input by 2, so 5 * 2 = 10.

❓ assertion

advanced

Correct Assertion for Integration Test

Which assertion correctly verifies that two integrated components return the expected combined result?

Testing Fundamentals

def component_x():
    return 'Hello'

def component_y():
    return 'World'

combined = component_x() + ' ' + component_y()

A assert combined != 'Hello World'

B assert combined == 'HelloWorld'

C assert combined == 'Hello World'

D assert combined is None

💡 Hint

Check the exact string value stored in combined.

The combined string includes a space between 'Hello' and 'World', so the assertion must match 'Hello World'.

🔧 Debug

advanced

Identify the Integration Test Bug

Find the bug in this integration test code that causes the test to fail unexpectedly.

Testing Fundamentals

def api_call():
    return {'status': 200, 'data': [1, 2, 3]}

def process_data():
    response = api_call()
    return response['data'][3]

result = process_data()

A TypeError because response is not a dictionary

B IndexError because response['data'][3] is out of range

C KeyError because 'data' key is missing

D No error, result is 3

💡 Hint

Check the length of the list and the index accessed.

The list has indices 0,1,2. Accessing index 3 causes an IndexError.

❓ framework

expert

Best Practice for Integration Test Isolation

In integration testing, which approach best ensures tests do not affect each other when accessing shared resources like databases?

A Use mock objects to simulate external services and reset database state before each test

B Run all tests in parallel without resetting any state

C Only test one integration at a time manually

D Ignore database state and rely on production data

💡 Hint

Think about how to keep tests independent and repeatable.

Using mocks and resetting database state before each test keeps tests isolated and reliable.

Practice

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

easy

A. To test the software's performance under load

B. To test individual functions or methods in isolation

C. To verify the final system meets user requirements

D. To check if different modules work together correctly

Solution

1. Step 1: Understand integration testing scope

   Integration testing focuses on testing combined parts or modules of software to ensure they work together.

2. Step 2: Differentiate from other testing types

   Unit testing checks individual parts, system testing checks the whole system, and performance testing checks speed/load.

3. Final Answer:

   To check if different modules work together correctly -> Option D

4. Quick Check:

   Integration testing = module interaction check [OK]

Hint: Integration testing checks module connections, not single parts [OK]

Common Mistakes:

• Confusing integration testing with unit testing
• Thinking integration testing is the final system test
• Mixing integration testing with performance testing

2. Which of the following is the correct sequence of testing phases including integration testing?

easy

A. Integration testing -> Unit testing -> System testing

B. Unit testing -> Integration testing -> System testing

C. System testing -> Integration testing -> Unit testing

D. System testing -> Unit testing -> Integration testing

Solution

1. Step 1: Recall testing order

   Unit testing is done first on individual parts, then integration testing checks combined parts, finally system testing checks the whole system.

2. Step 2: Match sequence with options

   Only Unit testing -> Integration testing -> System testing correctly shows Unit testing -> Integration testing -> System testing.

3. Final Answer:

   Unit testing -> Integration testing -> System testing -> Option B

4. Quick Check:

   Testing order = Unit -> Integration -> System [OK]

Hint: Remember testing flows from small parts to whole system [OK]

Common Mistakes:

• Mixing up the order of testing phases
• Thinking integration testing comes after system testing
• Assuming unit testing is last

3. Consider two modules: ModuleA returns a number, and ModuleB doubles that number. Which integration test output is correct if ModuleA returns 5?

medium

A. 10

B. 5

C. 25

D. Error

Solution

1. Step 1: Understand module behavior

   ModuleA returns 5; ModuleB doubles input, so it should return 5 * 2 = 10.

2. Step 2: Determine integration output

   When ModuleB receives 5 from ModuleA, output is 10, so integration test should expect 10.

3. Final Answer:

   10 -> Option A

4. Quick Check:

   5 doubled = 10 [OK]

Hint: Multiply ModuleA output by 2 for ModuleB result [OK]

Common Mistakes:

• Confusing input and output values
• Multiplying instead of doubling
• Expecting original value without processing

4. You wrote an integration test for two modules, but the test fails with a null pointer error. What is the most likely cause?

medium

A. Modules are not properly connected or data is missing between them

B. Unit tests for each module passed successfully

C. The system testing phase was skipped

D. The test environment has too much memory

Solution

1. Step 1: Analyze null pointer error in integration

   Null pointer errors usually happen when one module expects data from another but receives nothing or null.

2. Step 2: Connect error to module interaction

   If modules are not properly connected or data is missing, integration test fails with null pointer.

3. Final Answer:

   Modules are not properly connected or data is missing between them -> Option A

4. Quick Check:

   Null pointer = missing data between modules [OK]

Hint: Null pointer in integration means missing connection/data [OK]

Common Mistakes:

• Assuming unit tests guarantee integration success
• Blaming system testing for integration errors
• Ignoring environment issues unrelated to null pointers

5. You have three modules: Auth, Profile, and Notifications. Auth sends user info to Profile, which then triggers Notifications. Which integration test scenario best checks the full flow?

hard

A. Test Auth alone for correct login

B. Test Profile updates without Auth

C. Test Auth sending data to Profile and Profile triggering Notifications

D. Test Notifications independently for message format

Solution

1. Step 1: Identify integration points

   The flow involves Auth sending data to Profile, then Profile triggering Notifications. Testing this chain checks integration.

2. Step 2: Choose scenario covering full module interaction

   Only Test Auth sending data to Profile and Profile triggering Notifications tests the full flow of data and triggers across all three modules together.

3. Final Answer:

   Test Auth sending data to Profile and Profile triggering Notifications -> Option C

4. Quick Check:

   Full flow test = Auth -> Profile -> Notifications [OK]

Hint: Test full chain of modules for integration [OK]

Common Mistakes:

• Testing modules in isolation only
• Skipping intermediate module triggers
• Ignoring data flow between modules