Code review as testing in Testing Fundamentals - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of Code Review in Testing

What is the main purpose of performing a code review as part of software testing?

A To rewrite the code in a different programming language

B To increase the code size for better performance

C To find and fix bugs before the code runs in production

D To remove all comments and documentation from the code

💡 Hint

Think about how code review helps catch problems early.

Code review helps testers and developers find bugs and issues in the code before it is deployed, improving software quality.

❓ assertion

intermediate

Identifying a Good Assertion in Code Review

Which assertion best checks that a function returns the expected output during a code review?

Testing Fundamentals

def add(a, b):
    return a + b

result = add(2, 3)
# Which assertion is correct to verify the result?

A assert result == '5'

B assert result == 5

C assert result > 10

D assert result != 5

💡 Hint

Check what the function is supposed to return for inputs 2 and 3.

The function adds two numbers, so 2 + 3 equals 5. The assertion should check for equality with 5.

🔧 Debug

advanced

Finding the Bug in Code Snippet

During code review, you find this Python function. What error will it cause when called?

Testing Fundamentals

def divide(x, y):
    return x / y

result = divide(10, 0)

A No error, returns 0

B TypeError

C NameError

D ZeroDivisionError

💡 Hint

What happens when you divide a number by zero in Python?

Dividing by zero in Python raises a ZeroDivisionError at runtime.

❓ framework

advanced

Best Practice for Code Review in Testing Frameworks

Which practice is best when reviewing test code in an automated testing framework?

A Check that test cases have clear, descriptive names and cover edge cases

B Ignore test case names and focus only on code length

C Remove all comments to make tests shorter

D Write tests that depend on external systems without mocks

💡 Hint

Think about what makes tests easy to understand and reliable.

Good test code should have clear names and cover important cases, making it easier to maintain and trust.

❓ Predict Output

expert

Output of Code Review Scenario with Assertion

What is the output when running this test code snippet?

Testing Fundamentals

def is_even(n):
    return n % 2 == 0

assert is_even(7) == True

A AssertionError

B True

C False

D SyntaxError

💡 Hint

Check if 7 is even and what the assertion expects.

7 is not even, so is_even(7) returns False. The assertion expects True, so it fails with AssertionError.

Practice

1. What is the main purpose of code review in software testing?

easy

A. To find bugs and improve code quality before running the code

B. To write new features faster

C. To deploy code to production immediately

D. To replace automated testing completely

Solution

1. Step 1: Understand code review purpose

   Code review is done to check code manually for errors and improvements before execution.

2. Step 2: Compare options with purpose

   Only To find bugs and improve code quality before running the code matches the goal of finding bugs and improving quality before running code.

3. Final Answer:

   To find bugs and improve code quality before running the code -> Option A

4. Quick Check:

   Code review = find bugs early [OK]

Hint: Code review finds bugs before running code [OK]

Common Mistakes:

• Thinking code review replaces automated tests
• Believing code review speeds up deployment
• Confusing code review with coding new features

2. Which of the following is the correct way to give feedback during a code review?

easy

A. Provide clear, constructive comments with examples

B. Only comment if you find a syntax error

C. Ignore small mistakes to save time

D. Say 'This code is bad' without explanation

Solution

1. Step 1: Understand effective feedback

   Good feedback is clear, constructive, and helps improve code with examples.

2. Step 2: Evaluate options

   Provide clear, constructive comments with examples matches this approach; others are either rude, incomplete, or ignore issues.

3. Final Answer:

   Provide clear, constructive comments with examples -> Option A

4. Quick Check:

   Constructive feedback = clear + helpful [OK]

Hint: Be clear and helpful in feedback [OK]

Common Mistakes:

• Giving vague or rude comments
• Ignoring minor but important issues
• Only pointing out syntax errors

3. During a code review, you see this Python snippet:

def add_numbers(a, b):
    return a + b

result = add_numbers(2, '3')
print(result)

What will happen when this code runs?

medium

A. It will print 5

B. It will print 23

C. It will raise a TypeError

D. It will print null

Solution

1. Step 1: Analyze function call with mixed types

   The function adds an integer 2 and a string '3', which is invalid in Python.

2. Step 2: Understand Python behavior on adding int and str

   Python raises a TypeError when trying to add int and str directly.

3. Final Answer:

   It will raise a TypeError -> Option C

4. Quick Check:

   int + str = TypeError [OK]

Hint: Adding int and string causes TypeError in Python [OK]

Common Mistakes:

• Assuming Python converts string to int automatically
• Thinking it concatenates as strings
• Expecting numeric addition without error

4. You find this JavaScript code during review:

function multiply(x, y) {
  return x * y;
}

console.log(multiply(5));

What is the issue and how to fix it?

medium

A. multiply is missing one argument; fix by passing two arguments

B. multiply returns NaN; fix by setting default value for y

C. No issue; it prints 5

D. multiply throws error; fix by wrapping in try-catch

Solution

1. Step 1: Check function call with missing argument

   Calling multiply(5) passes only one argument; y is undefined.

2. Step 2: Understand JavaScript behavior multiplying number and undefined

   Multiplying number by undefined results in NaN (Not a Number).

3. Step 3: Fix by setting default value for y

   Use default parameter like function multiply(x, y = 1) to avoid NaN.

4. Final Answer:

   multiply returns NaN; fix by setting default value for y -> Option B

5. Quick Check:

   Missing arg causes NaN; default fixes [OK]

Hint: Missing JS args can cause NaN; use defaults [OK]

Common Mistakes:

• Assuming missing argument is zero
• Expecting error instead of NaN
• Ignoring default parameter usage

5. You review this Python code snippet:

data = [1, 2, 3, 4, 5]
result = {x: x*2 for x in data if x > 2}
result[3] = 10
print(result)

What is the final output and what does it teach about code review?

hard

A. {3: 6, 4: 8, 5: 10} - Code review helps spot logic and mutation issues

B. {1: 2, 2: 4, 3: 6, 4: 8, 5: 10} - Code review ensures all data processed

C. Error - Code review prevents runtime exceptions

D. {3: 10, 4: 8, 5: 10} - Code review helps catch unintended data changes

Solution

1. Step 1: Understand dictionary comprehension with condition

   Creates dict with keys 3,4,5 and values doubled: {3:6,4:8,5:10}.

2. Step 2: Note mutation of result[3]

   Code changes key 3's value from 6 to 10 explicitly.

3. Step 3: Final output and lesson

   Prints {3:10,4:8,5:10}. Code review helps catch such unintended mutations.

4. Final Answer:

   {3: 10, 4: 8, 5: 10} - Code review helps catch unintended data changes -> Option D

5. Quick Check:

   Mutation changes dict; review catches it [OK]

Hint: Check data changes carefully during review [OK]

Common Mistakes:

• Ignoring dictionary mutation after comprehension
• Assuming all data keys included
• Expecting error instead of changed output