Software Engineering basics - Path Testing in Software Engineering

Path Testing in Software Engineering

Definition

Path Testing is a white-box testing technique used to ensure that all possible execution paths in a program are tested at least once.

It focuses on the control flow of the program — that is, the sequence in which statements, decisions, and loops are executed.

Purpose of Path Testing

• To detect logic errors in the code.

• To ensure complete coverage of different execution paths.

• To validate that all decisions and conditions in the code behave correctly.

• To improve the reliability and quality of the software.

Key Concepts

1. Control Flow Graph (CFG):
   A diagram representing the flow of control in a program.

   • Nodes represent statements or blocks of code.

   • Edges represent the flow of control between them.

2. Path:
   A sequence of statements executed from the program’s start to end.

3. Independent Path:
   A path that introduces at least one new edge (or condition) not covered by previous paths.

4. Basis Path Testing:
   A structured form of path testing that ensures minimum number of test cases to cover all independent paths.

Steps Involved in Path Testing

Diagram: Path Testing (Example)

Here’s a simple example and its corresponding flow:

Code Example:

if A > 0:
    if B > 0:
        print("Path 1")
    else:
        print("Path 2")
else:
    print("Path 3")

Control Flow Graph:

        [Start]
           │
           ▼
       [Check A>0]
        /       \
      Yes         No
     /              \
[Check B>0]         [Path 3]
   /     \
Yes       No
 |         |
[Path 1] [Path 2]

Possible Paths:

1. Start → A>0 (True) → B>0 (True) → Path 1

2. Start → A>0 (True) → B>0 (False) → Path 2

3. Start → A>0 (False) → Path 3

Each of these paths represents an independent path that should be tested.

Cyclomatic Complexity Calculation

For the above CFG:

• Nodes (N) = 6

• Edges (E) = 7
  Formula:
  [
  V(G) = E - N + 2 = 7 - 6 + 2 = 3
  ]

So, 3 independent paths need to be tested.

Advantages of Path Testing

• Ensures logical completeness of the code.

• Identifies unreachable code or redundant paths.

• Useful for testing complex decision structures.

• Helps improve code quality and reliability.

Disadvantages

• Becomes complex for large programs.

• Not suitable for black-box testing (since it requires code access).

• Requires technical expertise to analyze the control flow graph.

Summary