White-box testing techniques in Software Engineering - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Statement Coverage

Which of the following best describes statement coverage in white-box testing?

A It measures whether every line of code has been executed at least once during testing.

B It ensures every possible input value is tested for the program.

C It verifies that all user interface elements are accessible.

D It checks if the software meets the business requirements.

💡 Hint

Think about coverage related to code lines executed.

Statement coverage means testing so that every line of code runs at least once. This helps find parts of code that never run.

📋 Factual

intermediate

Branch Coverage Purpose

What is the main goal of branch coverage in white-box testing?

A To ensure that both true and false outcomes of every decision point in the code are tested.

B To verify the software's performance under load.

C To ensure the software's user interface is intuitive.

D To check if the software handles invalid inputs gracefully.

💡 Hint

Focus on decision points and paths in code.

Branch coverage ensures that every possible branch (true/false) of each decision is tested.

🔍 Analysis

advanced

Evaluating Loop Testing Techniques

Consider a loop that runs from 1 to 10. Which white-box testing technique focuses on testing the loop with zero, one, and multiple iterations?

A Path coverage

B Condition coverage

C Loop testing

D Data flow testing

💡 Hint

Think about testing loops specifically.

Loop testing targets loops by checking cases like zero iterations, one iteration, and many iterations to find loop-related errors.

❓ Comparison

advanced

Difference Between Condition and Decision Coverage

Which statement correctly distinguishes condition coverage from decision coverage in white-box testing?

A Condition coverage ensures all code lines run; decision coverage ensures all functions are called.

B Condition coverage tests all possible input values; decision coverage tests all output values.

C Condition coverage focuses on user interface elements; decision coverage focuses on database queries.

D Condition coverage tests each boolean sub-expression independently; decision coverage tests the overall decision outcome.

💡 Hint

Think about testing parts of a decision versus the whole decision.

Condition coverage tests each condition inside a decision separately, while decision coverage tests the final true/false result of the entire decision.

❓ Reasoning

expert

Choosing the Best Technique for Complex Code Paths

You have a complex function with many nested decisions and loops. Which white-box testing technique is best suited to ensure all possible execution paths are tested?

A Statement coverage

B Path coverage

C Loop testing

D Condition coverage

💡 Hint

Consider the technique that covers all sequences of decisions.

Path coverage tests every possible route through the code, including all combinations of decisions and loops, making it ideal for complex code.

Practice

1. Which of the following best describes white-box testing?

easy

A. Testing that examines the internal structure of the code

B. Testing that focuses only on user interface behavior

C. Testing done without knowledge of the code

D. Testing that only checks software performance

Solution

1. Step 1: Understand white-box testing definition

   White-box testing involves looking inside the code to test its logic and structure.

2. Step 2: Compare options to definition

   Testing that examines the internal structure of the code matches this definition exactly, while others focus on external or unrelated aspects.

3. Final Answer:

   Testing that examines the internal structure of the code -> Option A

4. Quick Check:

   White-box testing = internal code check [OK]

Hint: White-box tests look inside the code, not just outside [OK]

Common Mistakes:

• Confusing white-box with black-box testing
• Thinking white-box tests only check UI
• Assuming white-box ignores code structure

2. Which syntax correctly represents a common white-box testing technique?

easy

A. User acceptance testing

B. Branch coverage

C. Load testing

D. Smoke testing

Solution

1. Step 1: Identify white-box testing techniques

   Common white-box techniques include statement, branch, path, and condition coverage.

2. Step 2: Match options to white-box techniques

   Only branch coverage is a white-box technique; others are types of testing but not white-box.

3. Final Answer:

   Branch coverage -> Option B

4. Quick Check:

   Branch coverage = white-box technique [OK]

Hint: Branch coverage is a classic white-box technique [OK]

Common Mistakes:

• Confusing black-box tests with white-box
• Choosing performance or acceptance tests
• Ignoring coverage-based techniques

3. Consider the following code snippet:

if (x > 0) {
  print("Positive");
} else {
  print("Non-positive");
}

Which white-box testing technique ensures both if and else branches are tested?

medium

A. Statement coverage

B. Path coverage

C. Branch coverage

D. Condition coverage

Solution

1. Step 1: Understand the code branches

   The code has two branches: one for x > 0 true, one for false.

2. Step 2: Identify technique testing all branches

   Branch coverage requires testing each branch (if and else) at least once.

3. Final Answer:

   Branch coverage -> Option C

4. Quick Check:

   Branch coverage = test all branches [OK]

Hint: Branch coverage tests all decision paths [OK]

Common Mistakes:

• Confusing statement coverage with branch coverage
• Thinking path coverage is simpler
• Ignoring else branch testing

4. A tester wrote this code to check condition coverage:

if (a > 10 && b < 5) {
  print("Valid");
}

Which mistake would cause incomplete condition coverage?

medium

A. Testing only when both conditions are true

B. Testing when a is 5 and b is 3

C. Testing when a is 15 and b is 6

D. Testing when a is 20 and b is 2

Solution

1. Step 1: Understand condition coverage

   Condition coverage requires testing each condition (a > 10 and b < 5) as true and false separately.

2. Step 2: Analyze testing only both true

   If only tested when both are true, false cases for each condition are not tested, so coverage is incomplete.

3. Final Answer:

   Testing only when both conditions are true -> Option A

4. Quick Check:

   Condition coverage = test each condition true/false [OK]

Hint: Test each condition true and false separately [OK]

Common Mistakes:

• Testing only combined true cases
• Ignoring false condition tests
• Assuming one test covers all conditions

5. You want to ensure every possible route through this code is tested:

if (x > 0) {
  if (y > 0) {
    print("Both positive");
  } else {
    print("x positive, y non-positive");
  }
} else {
  print("x non-positive");
}

Which white-box testing technique best guarantees this?

hard

A. Condition coverage

B. Statement coverage

C. Branch coverage

D. Path coverage

Solution

1. Step 1: Identify all possible paths

   There are three paths: both x and y positive, x positive and y non-positive, x non-positive.

2. Step 2: Understand path coverage

   Path coverage requires testing every possible route through the code, covering all combinations of decisions.

3. Step 3: Compare with other techniques

   Statement and branch coverage do not guarantee all paths; condition coverage tests conditions but not all paths.

4. Final Answer:

   Path coverage -> Option D

5. Quick Check:

   Path coverage = test all routes [OK]

Hint: Path coverage tests every possible route through code [OK]

Common Mistakes:

• Confusing branch with path coverage
• Assuming statement coverage is enough
• Ignoring nested conditions