White Box Testing Technique

White Box Testing Technique with Example

White Box Testing is a software testing technique in which the internal structure, source code, and logic of an application are tested. It is also known as Clear Box Testing, Glass Box Testing, or Structural Testing.

In this testing approach, the tester has complete knowledge of the application’s internal code and design.

Why is it called White Box Testing?

It is called White Box because the tester can “see inside” the application, just like looking through a transparent (white) box.

Who Performs White Box Testing?

• Developers
• Automation Testers
• Testers with programming knowledge

What is Tested in White Box Testing?

• Source code
• Conditional logic (if–else)
• Loops and branches
• Code paths
• Security vulnerabilities

White Box Testing Techniques

1. Statement Coverage

Ensures that every line of code is executed at least once.

2. Branch Coverage

Ensures that every possible branch (true/false) is tested.

3. Path Coverage

Ensures that all possible execution paths in the code are tested.

4. Loop Coverage

Focuses on validating different loop conditions like zero, one, and multiple iterations.

White Box Testing Example

Consider the following Java code:

public int findMax(int a, int b) {
    if (a > b) {
        return a;
    } else {
        return b;
    }
}

Test Scenarios

• Test Case 1: a = 10, b = 5 → Output = 10 (if condition true)
• Test Case 2: a = 5, b = 10 → Output = 10 (else condition)

Using these two test cases, we achieve 100% statement and branch coverage.

Advantages of White Box Testing

• Improves code quality
• Helps identify hidden bugs
• Optimizes code performance
• Early defect detection

Disadvantages of White Box Testing

• Requires programming knowledge
• Time-consuming for large applications
• Cannot detect missing requirements

When to Use White Box Testing?

• Unit testing
• Code optimization
• Security testing
• Automation framework validation

Note: White Box Testing is usually combined with Black Box Testing to ensure complete test coverage.

White Box vs Black Box Testing

White Box Testing	Black Box Testing
Requires code knowledge	No code knowledge required
Focuses on internal logic	Focuses on functionality
Usually done by developers	Usually done by testers

Conclusion

White Box Testing is a powerful technique that ensures the internal quality of software. By testing code logic, branches, and paths, it helps deliver a stable, secure, and high-quality application.

Happy Testing! 🚀