Path coverage in Testing Fundamentals - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is path coverage in software testing?

Path coverage is a testing technique that ensures every possible route or path through a program's control flow is executed at least once during testing.

beginner

Why is path coverage important?

Path coverage helps find errors in complex decision logic by testing all possible paths, reducing the chance of hidden bugs.

intermediate

How does path coverage differ from statement coverage?

Statement coverage tests if each line of code runs at least once, while path coverage tests all possible paths through the code, including different decision outcomes.

intermediate

What is a challenge when using path coverage?

The number of paths can grow very large with many decisions, making full path coverage hard or impossible to achieve in practice.

beginner

Give an example of a simple program path.

For example, in an if-else statement, there are two paths: one where the if condition is true and one where it is false. Path coverage means testing both.

What does path coverage ensure in testing?

A Every possible path through the program is executed

B Every variable is initialized

C Every function is called once

D Every user input is validated

Path coverage means testing all possible routes through the program's control flow.

Which is a limitation of path coverage?

A It ignores decision points

B It tests only one path

C It can be impossible to test all paths in complex programs

D It only tests syntax errors

Because the number of paths grows quickly, full path coverage can be impractical.

Path coverage is more thorough than which of these?

A Code formatting

B Syntax checking

C Memory profiling

D Statement coverage

Path coverage tests all paths, while statement coverage only ensures each line runs once.

In an if-else statement, how many paths are there?

A One

B Two

C Three

D Four

There are two paths: one where the if condition is true, and one where it is false.

Which testing technique focuses on decision outcomes?

A Path coverage

B Load testing

C Usability testing

D Syntax checking

Path coverage tests all decision outcomes by covering all paths.

Explain path coverage and why it is useful in software testing.

Think about how many ways a program can run depending on decisions.

Describe a challenge testers face when trying to achieve full path coverage.

Consider what happens when many if-else or loops combine.

Practice

1. What does path coverage testing ensure in software testing?

easy

A. All possible routes through the code are tested

B. Only the most common routes are tested

C. Only the start and end points are tested

D. Only the user interface is tested

Solution

1. Step 1: Understand path coverage meaning

   Path coverage means testing every possible route or path through the code's decision points.

2. Step 2: Compare options with definition

   All possible routes through the code are tested matches this definition exactly, while others limit testing scope incorrectly.

3. Final Answer:

   All possible routes through the code are tested -> Option A

4. Quick Check:

   Path coverage = all routes tested [OK]

Hint: Path coverage means testing every route through code [OK]

Common Mistakes:

• Confusing path coverage with statement coverage
• Thinking it tests only common or simple paths
• Assuming it tests only UI or start/end points

2. Which of the following is the correct way to represent path coverage in a decision structure?

easy

A. Testing only the true branch of an if statement

B. Testing only the false branch of an if statement

C. Testing both true and false branches of an if statement

D. Skipping the if statement entirely

Solution

1. Step 1: Understand path coverage in decisions

   Path coverage requires testing all possible outcomes of decisions, including both true and false branches.

2. Step 2: Match options to requirement

   Only Testing both true and false branches of an if statement tests both branches, fulfilling path coverage requirements.

3. Final Answer:

   Testing both true and false branches of an if statement -> Option C

4. Quick Check:

   Both branches tested = path coverage [OK]

Hint: Test all branches of decisions for path coverage [OK]

Common Mistakes:

• Testing only one branch of a decision
• Ignoring false branches
• Skipping decision points

3. Consider this code snippet:

if (x > 0) {
  if (x < 10) {
    print("A");
  } else {
    print("B");
  }
} else {
  print("C");
}

How many unique paths must be tested for full path coverage?

medium

A. 2

B. 3

C. 4

D. 5

Solution

1. Step 1: Identify decision points and paths

   There are two if statements: outer (x > 0) and inner (x < 10). Paths are:
   1) x > 0 and x < 10 -> print "A"
   2) x > 0 and x >= 10 -> print "B"
   3) x <= 0 -> print "C"

2. Step 2: Count unique paths

   There are 3 unique paths through the code based on these conditions.

3. Final Answer:

   3 -> Option B

4. Quick Check:

   Two decisions create 3 paths [OK]

Hint: Count all decision outcomes to find paths [OK]

Common Mistakes:

• Counting only outer if branches
• Assuming paths multiply incorrectly
• Forgetting else branch path

4. You have this code:

if (a > 5) {
  if (b == 0) {
    print("X");
  }
} else {
  print("Y");
}

Which test case is missing for full path coverage?

medium

A. a = 6, b = 1

B. a = 6, b = 0

C. a = 4, b = 0

D. a = 4, b = 1

Solution

1. Step 1: Identify all paths

   Paths are:
   1) a > 5 and b == 0 -> print "X"
   2) a > 5 and b != 0 -> no print
   3) a <= 5 -> print "Y"

2. Step 2: Check test cases for coverage

   The test case a = 6, b = 1 covers path 2, which is missing from the others.

3. Final Answer:

   a = 6, b = 1 -> Option A

4. Quick Check:

   Test all branches including no-action paths [OK]

Hint: Include tests for conditions with no output too [OK]

Common Mistakes:

• Ignoring paths with no print or action
• Testing only true branches
• Missing else branch tests

5. Given this nested decision code:

if (x > 0) {
  if (y > 0) {
    print("P");
  } else {
    print("Q");
  }
} else {
  if (y > 0) {
    print("R");
  } else {
    print("S");
  }
}

How many test cases are needed for full path coverage, and why?

hard

A. 2, because only outer if matters

B. 5, because of extra hidden paths

C. 3, because some inner paths overlap

D. 4, because each if-else pair creates 2 paths

Solution

1. Step 1: Analyze nested if-else structure

   There are two if-else blocks nested:
   - Outer if (x > 0) with two inner paths (y > 0 and y <= 0)
   - Outer else (x <= 0) with two inner paths (y > 0 and y <= 0)

2. Step 2: Calculate total paths

   Each outer branch has 2 inner branches, so total paths = 2 (outer) * 2 (inner) = 4.

3. Final Answer:

   4, because each if-else pair creates 2 paths -> Option D

4. Quick Check:

   Nested if-else multiply paths = 4 [OK]

Hint: Multiply branches of nested decisions for paths count [OK]

Common Mistakes:

• Counting only outer or inner branches
• Assuming overlapping paths reduce count
• Adding extra paths without basis