Code coverage metrics in Software Engineering - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate the percentage of lines covered by tests.

Software Engineering

coverage_percentage = (covered_lines / [1]) * 100

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

Atotal_lines

Btest_lines

Cuncovered_lines

Dexecuted_lines

Attempts:

3 left

💡 Hint

Common Mistakes

Using test lines instead of total lines

Using uncovered lines as denominator

The total number of lines in the code is used as the denominator to calculate coverage percentage.

2fill in blank

medium

Complete the code to filter out functions that have zero coverage.

Software Engineering

functions_with_coverage = {f: c for f, c in coverage_data.items() if c > [1]

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

A0

B1

C-1

D100

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 excludes functions with partial coverage

Using 100 excludes all but fully covered functions

Functions with coverage greater than zero are considered covered.

3fill in blank

hard

Fix the error in the code to calculate branch coverage correctly.

Software Engineering

branch_coverage = (covered_branches / [1]) * 100

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

Atotal_lines

Btotal_branches

Ccovered_branches

Dexecuted_branches

Attempts:

3 left

💡 Hint

Common Mistakes

Using covered branches as denominator

Using total lines instead of branches

Branch coverage is the ratio of covered branches to total branches.

4fill in blank

hard

Fill both blanks to create a dictionary of functions with coverage above 80%.

Software Engineering

high_coverage_funcs = {f: c for f, c in coverage_data.items() if c [1] [2]

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

A>

B80

C>=

D75

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' includes 80% exactly

Using 75 is too low threshold

The code filters functions with coverage greater than 80%.

5fill in blank

hard

Fill all three blanks to create a summary dictionary with function names in uppercase and coverage above 50%.

Software Engineering

summary = { [1]: [2] for func, cov in coverage_data.items() if cov [3] 50 }

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

Afunc.upper()

Bcov

C>

Dfunc.lower()

Attempts:

3 left

💡 Hint

Common Mistakes

Using func.lower() instead of upper

Using '<' instead of '>' for filtering

The dictionary comprehension uses uppercase function names, coverage values, and filters coverage greater than 50%.

Practice

1. What does code coverage primarily measure in software testing?

easy

A. The number of developers working on the code

B. The number of bugs found in the code

C. The speed of the test execution

D. The percentage of code executed by tests

Solution

1. Step 1: Understand the purpose of code coverage

   Code coverage shows how much of the program's code is run during testing.

2. Step 2: Identify what code coverage measures

   It measures the percentage of code lines or branches executed by tests, not bugs or speed.

3. Final Answer:

   The percentage of code executed by tests -> Option D

4. Quick Check:

   Code coverage = executed code percentage [OK]

Hint: Code coverage = how much code tests run [OK]

Common Mistakes:

• Confusing coverage with bug count
• Thinking coverage measures test speed
• Assuming coverage counts developers

2. Which of the following is a common type of code coverage metric?

easy

A. Branch coverage

B. Memory coverage

C. Network coverage

D. User coverage

Solution

1. Step 1: Recall common code coverage types

   Common types include line coverage, branch coverage, and function coverage.

2. Step 2: Identify valid coverage types

   Branch coverage measures if all decision branches are tested; memory, network, and user coverage are not standard metrics.

3. Final Answer:

   Branch coverage -> Option A

4. Quick Check:

   Branch coverage is a standard metric [OK]

Hint: Branch coverage is a standard metric name [OK]

Common Mistakes:

• Choosing non-existent coverage types
• Confusing coverage with unrelated terms
• Ignoring common coverage categories

3. Consider a program with 100 lines of code. A test suite runs 80 lines and covers all branches in those lines. What is the approximate line coverage percentage?

medium

A. 20%

B. 100%

C. 80%

D. 50%

Solution

1. Step 1: Calculate line coverage

   Line coverage = (lines executed / total lines) x 100 = (80 / 100) x 100.

2. Step 2: Compute the percentage

   80 divided by 100 equals 0.8, multiplied by 100 gives 80% coverage.

3. Final Answer:

   80% -> Option C

4. Quick Check:

   80/100 = 0.8 = 80% [OK]

Hint: Divide executed lines by total lines, multiply by 100 [OK]

Common Mistakes:

• Confusing branch coverage with line coverage
• Calculating 100% because all branches covered
• Mixing up executed and total lines

4. A developer reports 90% code coverage, but some bugs remain. What is the most likely reason?

medium

A. High coverage does not guarantee all bugs are found

B. The coverage tool is broken

C. Tests ran too slowly

D. Code coverage measures bug count

Solution

1. Step 1: Understand code coverage limits

   Code coverage shows tested code amount but does not ensure test quality or bug detection.

2. Step 2: Identify why bugs remain

   Even with 90% coverage, tests might miss edge cases or logic errors causing bugs.

3. Final Answer:

   High coverage does not guarantee all bugs are found -> Option A

4. Quick Check:

   Coverage ≠ bug-free code [OK]

Hint: Coverage shows tested code, not bug absence [OK]

Common Mistakes:

• Assuming coverage means no bugs
• Blaming coverage tools without evidence
• Confusing coverage with test speed

5. You want to improve your test suite to cover all decision branches in a function with multiple if-else statements. Which approach best increases branch coverage?

hard

A. Write tests that only check the function's return value

B. Write tests that execute both true and false paths of each condition

C. Run the existing tests multiple times

D. Add print statements inside the function

Solution

1. Step 1: Understand branch coverage goal

   Branch coverage requires testing all possible paths of decision points (true and false).

2. Step 2: Choose the best testing approach

   Writing tests that cover both true and false branches ensures all decision paths run during testing.

3. Final Answer:

   Write tests that execute both true and false paths of each condition -> Option B

4. Quick Check:

   Branch coverage = test all decision paths [OK]

Hint: Test both true and false branches for full coverage [OK]

Common Mistakes:

• Testing only return values misses branches
• Rerunning tests doesn't increase coverage
• Adding print statements doesn't affect coverage