The Basics and Applications of Efficient Test Design with Equivalence Partitioning and Boundary Value Analysis

1. What Are Equivalence Partitioning and Boundary Value Analysis?

What is Equivalence Partitioning?

Equivalence Partitioning is a technique that divides the test range into “groups of values expected to produce the same result” (equivalence classes). Representative values from each group are then selected for testing. As a cornerstone of black-box testing, it enables efficient testing while covering input ranges.

Key Features:

• Reduces redundancy in input data
• Allows testing with a single representative value for each class
• Verifies how the system reacts to unexpected input

 

Example: Age Input Field (Range: 0–120)

• Valid Class: 0–120
• Invalid Classes: Less than 0, greater than 120

For example, selecting 30 from the valid class and -1 and 121 from the invalid classes ensures comprehensive test coverage.

 

What is Boundary Value Analysis?

Boundary Value Analysis is a technique that focuses on testing the “boundaries” of the ranges defined by equivalence classes. Since boundaries are common points of failure, they are particularly critical for testing. This method refines equivalence classes by ensuring edge cases are thoroughly tested.

Key Features:

• Efficiently detects errors near boundary values
• Enables focused, priority-driven test case design

 

Example: Boundary Values for Age Input Field

• Boundaries to test: -1, 0, 1, 119, 120, 121

 

2. Differences and Relationship Between Equivalence Partitioning and Boundary Value Analysis

Differences:

• Equivalence Partitioning: Focuses on grouping input values with expected similar behavior.
• Boundary Value Analysis: Focuses on testing the edges or boundaries of these groups.

 

Relationship:

Equivalence Partitioning efficiently sets up input groups, while Boundary Value Analysis targets the critical points (boundaries) within these groups, enhancing test accuracy and coverage. Together, they ensure efficient and comprehensive test case design.

 

3. Practical Applications of Equivalence Partitioning and Boundary Value Analysis

Example 1: Designing Test Cases for an Age Input Field

• Specification: Accepts ages between 0 and 120.
• Equivalence Partitioning:
  • Valid Class: 0–120 (e.g., 30)
  • Invalid Classes: Less than 0, greater than 120 (e.g., -5, 130)
• Boundary Value Analysis:
  • Boundaries: -1, 0, 1, 119, 120, 121

This approach covers critical areas with minimal test cases.

 

Example 2: Coupon Application Conditions

• Specification: Coupons are valid for purchases of ¥1,000 or more.
• Equivalence Partitioning:
  • Valid Class: ¥1,000 or more (e.g., ¥2,000)
  • Invalid Class: Less than ¥1,000 (e.g., ¥800)
• Boundary Value Analysis:
  • Boundaries: ¥999, ¥1,000, ¥1,001

 

Example 3: Password Length Validation

• Specification: Password must be 8–16 characters.
• Equivalence Partitioning:
  • Valid Class: 8–16 characters (e.g., 10 characters)
  • Invalid Classes: Less than 8, greater than 16 (e.g., 6, 20 characters)
• Boundary Value Analysis:
  • Boundaries: 7, 8, 16, 17 characters

 

4. Efficient Application of Equivalence Partitioning + Boundary Value Analysis

Accurate Understanding of Specifications:

Thorough understanding of system specifications is essential. Clarify ambiguities in the documentation by consulting developers or project managers.

 

Efficient Tool Utilization:

• Excel: Useful for managing and categorizing test cases.
• Test Management Tools (e.g., TestRail): Effective for large-scale projects.

 

Focus on Invalid Values:

Always include invalid cases to verify how the system handles unexpected inputs.

 

5. Best Practices to Maximize Test Efficiency

Utilize Automation:

Automate test cases using tools like Selenium or Postman for efficiency in repetitive testing.

 

Combine with Other Techniques:

Incorporate methods like State Transition Testing or Decision Table Testing to validate the overall system behavior.

 

6. Tips to Avoid Common Pitfalls

Overdesigning Test Cases:

Avoid creating unnecessary test cases. Carefully select representative values.

 

Mistakes in Boundary Setting:

Ensure accurate definition of boundaries to avoid missing critical bugs.

 

7. Achieve High-Quality Testing with Equivalence Partitioning + Boundary Value Analysis

By effectively utilizing Equivalence Partitioning and Boundary Value Analysis, you can optimize test cases and improve bug detection rates. Incorporating these techniques into your workflow ensures efficient and comprehensive test design, paving the way for higher-quality software.