Statement coverage in Testing Fundamentals - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Statement Coverage

Which of the following best describes statement coverage in software testing?

A It measures the percentage of executable statements in the code that have been executed by the test cases.

B It measures the percentage of decision outcomes (true/false) tested in the code.

C It measures the number of test cases executed during testing.

D It measures the time taken to execute all test cases.

💡 Hint

Think about what part of the code is actually run during testing.

Statement coverage checks if every line of code has been run at least once by the tests. It does not focus on decision outcomes or test case counts.

❓ Predict Output

intermediate

Calculate Statement Coverage Percentage

Given the following code and test cases, what is the statement coverage percentage?

def check_number(x):
    if x > 0:
        print("Positive")
    else:
        print("Non-positive")

# Test cases:
check_number(5)

A 25%

B 50%

C 100%

D 75%

💡 Hint

Count how many lines run when check_number(5) is called.

There are 4 executable statements: the if, the print("Positive"), the else, and print("Non-positive"). Only the if and print("Positive") run, so 2 out of 4 lines = 50% coverage.

❓ assertion

advanced

Assertion for Full Statement Coverage

Which assertion correctly verifies that a test suite achieves 100% statement coverage for the following function?

def is_even(n):
    if n % 2 == 0:
        return True
    else:
        return False

A assert statement_coverage(is_even_tests) == 0

B assert statement_coverage(is_even_tests) < 100

C assert statement_coverage(is_even_tests) >= 50

D assert statement_coverage(is_even_tests) == 100

💡 Hint

Full coverage means all lines run at least once.

To confirm 100% statement coverage, the assertion must check that coverage equals 100%. Other options are incorrect because they allow partial or no coverage.

🔧 Debug

advanced

Debugging Statement Coverage Measurement

Consider this test code measuring statement coverage. It reports 80% coverage, but the tester expects 100%. What is the likely cause?

def foo(x):
    if x > 0:
        print("Positive")
    else:
        print("Zero or Negative")

# Test cases
foo(1)
# Coverage measured here

A The function foo has a syntax error causing incomplete coverage.

B The print statements cause the coverage tool to fail.

C The test cases do not cover the else branch, so some statements are not executed.

D The coverage tool only measures function calls, not statements.

💡 Hint

Think about which lines run when foo(1) is called.

Calling foo(1) only runs the if branch, so the else branch statements are never executed, causing less than 100% coverage.

❓ framework

expert

Integrating Statement Coverage in Automated Testing

Which option correctly describes how to integrate statement coverage measurement into an automated Python test suite using pytest and coverage.py?

A Run tests with <code>coverage run -m pytest</code> then generate report with <code>coverage report</code>.

B Add <code>assert coverage == 100</code> inside each test function manually.

C Run tests with <code>pytest --coverage</code> without installing any extra tools.

D Use <code>pytest-cov</code> but coverage reports are generated automatically without any commands.

💡 Hint

Think about the standard commands to run coverage with pytest.

The correct way is to run tests under coverage using coverage run -m pytest and then generate a coverage report with coverage report. Option A is invalid because pytest alone does not support --coverage without plugins. Option A is incorrect because coverage is measured externally, not by assertions. Option A is wrong because reports require explicit commands.

Practice

1. What does statement coverage measure in software testing?

easy

A. The number of test cases written

B. The number of bugs found in the code

C. The time taken to run all tests

D. The percentage of code lines executed during testing

Solution

1. Step 1: Understand the definition of statement coverage

   Statement coverage measures how many lines of code are executed when tests run.

2. Step 2: Compare options to the definition

   Only The percentage of code lines executed during testing correctly describes statement coverage as the percentage of executed code lines.

3. Final Answer:

   The percentage of code lines executed during testing -> Option D

4. Quick Check:

   Statement coverage = executed code lines percentage [OK]

Hint: Statement coverage counts executed lines, not tests or bugs [OK]

Common Mistakes:

• Confusing statement coverage with number of test cases
• Thinking it measures bugs found
• Mixing it up with test execution time

2. Which of the following is the correct way to describe statement coverage in a test report?

easy

A. Statement coverage is the number of test cases executed.

B. Statement coverage is the percentage of code statements executed during testing.

C. Statement coverage is the total time taken to run all tests.

D. Statement coverage is the number of bugs found per test.

Solution

1. Step 1: Identify the correct definition for statement coverage in reports

   Statement coverage is reported as the percentage of code statements executed during tests.

2. Step 2: Match options to the correct definition

   Statement coverage is the percentage of code statements executed during testing. correctly states this; others confuse coverage with test count, time, or bugs.

3. Final Answer:

   Statement coverage is the percentage of code statements executed during testing. -> Option B

4. Quick Check:

   Statement coverage = % of executed statements [OK]

Hint: Coverage means percent of executed code lines, not test counts [OK]

Common Mistakes:

• Reporting coverage as number of tests
• Confusing coverage with test duration
• Mixing coverage with bug counts

3. Consider this code snippet:

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

If a test runs with x = 5, what is the statement coverage?

medium

A. 100% because all lines run

B. 75% because some lines run

C. 50% because only the if block runs

D. 0% because no else block runs

Solution

1. Step 1: Count total statements in the code

   There are 4 statements: the if condition, print("Positive"), else, print("Non-positive").

2. Step 2: Identify executed statements when x=5

   The if condition and print("Positive") run; else and its print do not run. So 2 out of 4 statements run.

3. Final Answer:

   50% because only the if block runs -> Option C

4. Quick Check:

   Executed statements = 2/4 = 50% [OK]

Hint: Only executed lines count; else block skipped means less coverage [OK]

Common Mistakes:

• Assuming else block runs anyway
• Counting conditions as multiple statements
• Thinking coverage is always 100%

4. You have this code:

if (a == 10) {
  print("Ten");
}
print("Done");

A test runs with a = 5 but reports 100% statement coverage. What is wrong?

medium

A. The test did not execute the if block, so coverage cannot be 100%

B. The print("Done") statement was not executed

C. The test input is invalid

D. The coverage tool counts only executed lines, so 100% is correct

Solution

1. Step 1: Identify statements and their execution

   There are 3 statements: if condition, print("Ten"), and print("Done"). With a=5, the if block is skipped, so print("Ten") is not executed.

2. Step 2: Check coverage report validity

   Since one statement is not executed, coverage cannot be 100%. The report is incorrect or the test did not run as expected.

3. Final Answer:

   The test did not execute the if block, so coverage cannot be 100% -> Option A

4. Quick Check:

   Skipped statements mean coverage less than 100% [OK]

Hint: Skipped code means coverage less than 100%, check test inputs [OK]

Common Mistakes:

• Assuming coverage counts unexecuted lines
• Ignoring skipped if blocks
• Trusting coverage tool blindly

5. Given this code:

if (score >= 90) {
  grade = 'A';
} else if (score >= 80) {
  grade = 'B';
} else {
  grade = 'C';
}

Which test inputs will achieve 100% statement coverage?

hard

A. score = 95, score = 85, and score = 70

B. score = 95 and score = 85

C. score = 95 only

D. score = 70 only

Solution

1. Step 1: Identify all statements in the code

   There are 7 statements: 3 conditions and 4 assignments (grade = 'A', grade = 'B', grade = 'C', plus else blocks).

2. Step 2: Determine inputs to cover all branches

   To cover all statements, tests must run each branch: score=95 covers first if, score=85 covers else if, score=70 covers else.

3. Final Answer:

   score = 95, score = 85, and score = 70 -> Option A

4. Quick Check:

   All branches covered by three inputs = 100% coverage [OK]

Hint: Test all branches to cover all statements fully [OK]

Common Mistakes:

• Testing only some branches
• Assuming one input covers all
• Ignoring else branch coverage