Code review as testing in Testing Fundamentals - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a function has a missing return statement during code review.

Testing Fundamentals

def check_return(func):
    source = func.__code__.co_code
    if [1] not in source:
        return False
    return True

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

ALOAD_FAST

BRETURN_VALUE

CCALL_FUNCTION

DLOAD_CONST

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing other opcodes like LOAD_CONST or CALL_FUNCTION with return.

The RETURN_VALUE opcode indicates a return statement in Python bytecode. Checking for it helps find missing returns.

2fill in blank

medium

Complete the code to identify if a variable name follows naming conventions during code review.

Testing Fundamentals

def is_valid_var(name):
    import re
    pattern = r'^[a-z_][a-z0-9_]*$'
    return bool(re.match([1], name))

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

A'^[A-Z][a-zA-Z0-9]*$'

B'^[A-Za-z]+$'

C'^[0-9][a-z_]*$'

D'^[a-z_][a-z0-9_]*$'

Attempts:

3 left

💡 Hint

Common Mistakes

Using patterns that allow uppercase first letters or digits at start.

The pattern '^[a-z_][a-z0-9_]*$' matches valid Python variable names starting with lowercase or underscore.

3fill in blank

hard

Fix the error in the code review function that checks for TODO comments in code.

Testing Fundamentals

def has_todo_comment(code_lines):
    for line in code_lines:
        if '[1]' in line:
            return True
    return False

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

A"todo"

B"TODO"

C"# TODO"

D"#todo"

Attempts:

3 left

💡 Hint

Common Mistakes

Searching only for 'TODO' without the comment symbol, causing false positives.

Checking for "# TODO" ensures we find proper TODO comments with the hash symbol and uppercase TODO.

4fill in blank

hard

Fill both blanks to create a code review function that finds functions missing docstrings.

Testing Fundamentals

def missing_docstring(func):
    doc = func.__doc__
    if doc is [1] or doc.strip() == [2]:
        return True
    return False

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

ANone

B""

C"None"

D''

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for string 'None' instead of None type.

A function missing a docstring has __doc__ as None or an empty string "".

5fill in blank

hard

Fill all three blanks to create a code review snippet that collects all function names missing type hints.

Testing Fundamentals

def functions_missing_type_hints(module):
    missing = []
    for name, func in module.__dict__.items():
        if callable(func) and ([1] not in func.__annotations__ or [2] not in func.__annotations__):
            missing.append([3])
    return missing

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

A"return"

B"param"

Cname

D"return_type"

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect keys for annotations or appending the wrong variable.

Type hints are stored in __annotations__ with keys for parameters and 'return'. Here, 'return' and 'param' are placeholders for keys, and name is appended.

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