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Boundary Value Analysis (BVA)

Boundary Value Analysis (BVA) is a test case design technique that focuses on testing the boundary values of input ranges, where defects are most likely to occur.

BVA answers: “What happens at the edges of valid and invalid input ranges?”

1. Definition

Boundary Value Analysis (BVA) is a test case design technique that focuses on testing the boundary values of input ranges, where defects are most likely to occur.

BVA answers: “What happens at the edges of valid and invalid input ranges?”

2. Why Boundary Values Are Important

  • Defects often occur at limits
  • Developers frequently make mistakes with <, >, <=, >=
  • Boundary-related bugs are common and critical

3. Relationship Between EP and BVA

  • Equivalence Partitioning identifies valid/invalid ranges
  • BVA tests the edges of those ranges

They are usually used together.

4. How to Apply Boundary Value Analysis (Steps)

  1. Identify the input range
  2. Identify minimum and maximum values
  3. Select boundary values:
    • Minimum
    • Minimum + 1
    • Maximum − 1
    • Maximum
  4. (Optional: include just-below and just-above boundaries)

5. Real-Time Example

Age field requirement: Age must be between 18 and 60 (inclusive).

Boundary test values:

  • 17 → Invalid (just below min)
  • 18 → Valid (min boundary)
  • 19 → Valid (min + 1)
  • 59 → Valid (max − 1)
  • 60 → Valid (max boundary)
  • 61 → Invalid (just above max)

6. Types of Boundary Value Analysis

6.1 Normal Boundary Value Analysis

  • Tests only valid boundaries

6.2 Robust Boundary Value Analysis

  • Tests valid and invalid boundaries

7. When to Use BVA

  • Numeric fields
  • Date ranges
  • Length-based fields (password length, text size)
  • Limits and thresholds

8. BVA vs Equivalence Partitioning

Aspect BVA Equivalence Partitioning
Focus Edge values Input groups
Test cases More Fewer
Defect detection High Medium

9. Common Mistakes

  • Ignoring boundary values
  • Testing only one side of boundary
  • Mixing EP and BVA incorrectly

10. Interview-Ready Answers

Short answer:

Boundary Value Analysis is a technique that focuses on testing the boundary values of input ranges.

Detailed answer:

BVA tests values at and around the edges of valid and invalid input ranges, where defects are most likely to occur.

11. Key Takeaway

Boundary Value Analysis targets high-risk areas and is one of the most effective manual testing techniques.