Boundary Value Analysis

Boundary Value Analysis (BVA) is a software testing technique used to identify defects by focusing on test cases that target the boundaries of input domains. It is based on the observation that errors are more likely to occur at the extreme edges or boundaries of input ranges rather than in the middle of these ranges. By testing at, just inside, and just outside the boundaries, BVA ensures comprehensive validation of how the system handles edge conditions.

Key Characteristics of Boundary Value Analysis

• Focus on Boundaries: It targets the transition points between valid and invalid input ranges or between distinct valid ranges.
• Systematic Testing: BVA ensures that all critical boundary conditions are systematically tested, reducing the likelihood of missed defects.
• Applicability: It is widely applicable to systems with clearly defined input ranges, such as numerical fields, date ranges, and string lengths.

Process of Boundary Value Analysis

1. Identify Input Ranges: determine the valid and invalid input domains based on the system’s requirements or specifications.

   For example, a field accepting values between 1 and 100 has boundaries at 1 (lower boundary) and 100 (upper boundary).

2. Select Boundary Values: choose test cases that include:
   • On-Boundary Values: Inputs exactly at the boundaries (e.g., 1 and 100).
   • Inside-Boundary Values: Inputs just within the valid range (e.g., 2 and 99).
   • Outside-Boundary Values: Inputs just outside the valid range (e.g., 0 and 101).
3. Design Test Cases: develop test cases based on the selected boundary values, ensuring the system’s expected behavior is defined for each case.
4. Execute and Analyze: run the test cases and compare the system’s actual behavior with expected outcomes to identify any defects.