Intermediate⏱ 6 min read
Boundary Value Analysis & Equivalence Partitioning
sign in to trackEquivalence Partitioning (EP) divides input data into classes where all values in a class should behave identically. Boundary Value Analysis (BVA) focuses testing on the values at the edges of those partitions, where most defects cluster.
◈Key Points
- EP: Instead of testing 1,000 valid ages, test one — they all exercise the same code path.
- BVA: For an age field accepting 18–65, test: 17, 18, 19, 64, 65, 66 — boundaries catch off-by-one errors.
- Three-value BVA tests the boundary, one below, and one above each partition edge.
- Apply to both valid and invalid partitions — invalid inputs are as important as valid ones.
- EP + BVA together dramatically reduce test case count while maintaining defect detection power.
⚡ Expert Pro Tip
Off-by-one errors are one of the most common defects in software. BVA is the single most cost-effective technique for catching them systematically.