Code review as testing in Testing Fundamentals - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is code review in software testing?

Code review is a process where developers check each other's code to find mistakes before running the program. It helps catch errors early and improves code quality.

beginner

Why is code review considered a form of testing?

Because it helps find bugs and problems in the code without running it. It acts like a manual check to ensure the code works as expected.

beginner

Name two benefits of code review as testing.

1. Finds bugs early before running the code.
2. Shares knowledge among team members.

intermediate

What should reviewers focus on during a code review?

Reviewers should check for correct logic, clear code, adherence to standards, and possible errors or security issues.

intermediate

How does code review improve software quality?

By catching mistakes early, improving code clarity, and encouraging good coding habits, code review helps create more reliable and maintainable software.

What is the main goal of code review as testing?

A Run the program faster

B Write new features

C Find bugs and improve code before running it

D Deploy software to users

Code review helps find bugs and improve code quality before the software runs.

Who usually performs code reviews?

A Developers reviewing each other's code

B End users

C Marketing team

D Automated robots only

Developers check each other's code to find mistakes and improve quality.

Which of these is NOT a focus during code review?

A Checking code logic

B Checking spelling in comments

C Checking adherence to coding standards

D Checking for security issues

While comments should be clear, spelling is less important than logic, standards, and security.

Code review helps improve software quality by:

A Catching errors early and sharing knowledge

B Making software run slower

C Adding more bugs

D Replacing testing completely

Code review finds errors early and helps team members learn from each other.

When is the best time to do a code review?

A Never

B After deployment

C After users report bugs

D Before running the code

Reviewing code before running helps catch problems early.

Explain how code review acts as a testing method and why it is important.

Think about how reading code carefully can find mistakes early.

List key things to look for during a code review to ensure good software quality.

Focus on what makes code safe, clear, and correct.

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