Boundary Value Analysis Techniques: A Practical Tutorial

1. Introduction

1.1 Tutorial Goal

This tutorial aims to provide a comprehensive understanding of Boundary Value Analysis techniques, a crucial part of software testing. We'll explore what Boundary Value Analysis is, why it's important, and how to apply it in real-world scenarios.

1.2 Learning Outcomes

By the end of this tutorial, you will understand:

• The concept of Boundary Value Analysis
• The steps involved in performing Boundary Value Analysis
• How to implement Boundary Value Analysis with code examples

1.3 Prerequisites

This tutorial assumes a basic understanding of software testing concepts. Familiarity with a programming language will be beneficial but not mandatory.

2. Step-by-Step Guide

2.1 What is Boundary Value Analysis?

Boundary Value Analysis (BVA) is a black box testing technique where you test boundary values of the input domain at both ends: the start and the end. This technique is based on the principle that bugs are most likely to be found at the boundaries rather than in the center of the input domain.

2.2 Performing Boundary Value Analysis

To perform BVA, follow these steps:

1. Identify all the input variables of the system.
2. For each input, identify the lower and upper boundaries.
3. Create test cases for the exact boundary values, as well as just below and just above the boundary values.

2.3 Best Practices and Tips

• Always test the boundary values and their immediate neighbors.
• Don't forget to test for invalid boundary values as well.

3. Code Examples

3.1 Example 1: Testing a Function that Returns Age Group

The function getAgeGroup(age) returns the age group of a person based on their age:

# Age Group Function
def getAgeGroup(age):
    if age < 13:
        return "Child"
    elif age < 20:
        return "Teenager"
    elif age < 60:
        return "Adult"
    else:
        return "Senior"

Here, the boundaries are at ages 13, 20, and 60. So, we should test these values as well as one below and one above each boundary. For example:

# Test cases for boundary values
print(getAgeGroup(12)) # Expected "Child"
print(getAgeGroup(13)) # Expected "Teenager"
print(getAgeGroup(14)) # Expected "Teenager"

3.2 Example 2: Testing a Function that Validates Password Length

The function isPasswordValid(password) returns True if the password length is between 8 and 16 characters, inclusive:

// Password Validation Function
function isPasswordValid(password) {
    return password.length >= 8 && password.length <= 16;
}

The boundaries are at lengths 8 and 16. We test these values and their neighbors:

// Test cases for boundary values
console.log(isPasswordValid("abcdefg")) // Expected false
console.log(isPasswordValid("abcdefgh")) // Expected true
console.log(isPasswordValid("abcdefghijklmnopq")) // Expected false

4. Summary

• We learned about Boundary Value Analysis and its significance in software testing.
• We've seen how to conduct BVA by identifying and testing boundary values.
• We explored practical code examples to solidify our understanding.

5. Practice Exercises

5.1 Exercise 1: Testing a Function that Categorizes Scores

Write a function getScoreCategory(score) that categorizes a score between 0 and 100 into "Poor", "Average", "Good", and "Excellent". Identify the boundary values and write test cases for them.

5.2 Exercise 2: Testing a Function that Validates Usernames

Write a function isUsernameValid(username) that validates a username. The username must be between 5 and 15 characters long, and must start with a letter. Identify the boundary values and write test cases for them.

5.3 Exercise 3: Testing a Function that Calculates Shipping Cost

Write a function calculateShipping(weight) that calculates shipping cost based on weight. The shipping costs are $5 for weight up to 1kg, $10 for up to 5kg, and $20 for more than 5kg. Identify the boundary values and write test cases for them.

Remember, practice makes perfect. Happy testing!