Testing
Every non-trivial software system has state. A shopping cart is empty, then has items, then is checked out. A door is locked, unlocked, or open. A connection is connecting, connected, or disconnected. Finite state machines (FSMs) are a precise way to model that state — and state machine testing is
Test Design
Equivalence partitioning for a single input is straightforward: identify the behavioral regions, pick one representative from each. Multi-variable and stateful systems are harder because the partitions aren't independent — the valid values for one variable depend on the state of another. This post covers EP for systems with
Test Design
Most equivalence partitioning (EP) tutorials use age ranges and temperature thresholds. Clean, numeric, easy to understand. The real world is messier: username validation, date ranges with timezone edge cases, enum state machines, and variable-length collections. This post covers EP for non-numeric input types where the partition boundaries aren&
Testing
Equivalence partitioning and boundary value analysis are two of the oldest and most effective black-box test design techniques. They are taught in every software testing curriculum, appear on every certification exam, and yet are frequently applied mechanically without real understanding — resulting in test suites that look thorough but miss
Testing Strategy
Business logic is where bugs are most expensive. A bug in your discount calculation, insurance eligibility rule, or loan approval logic doesn't just throw an error—it silently gives the wrong answer, affecting real customers and real money. Decision table testing is a systematic technique for deriving test
Testing Strategy
Testing every combination of input parameters is mathematically impossible for most systems. Three boolean parameters create 8 combinations. Ten parameters with 3 values each create 59,049 combinations. A car has around 500 features with binary toggles—more combinations than atoms in the universe. Combinatorial testing solves this by using
API Testing
API testing benefits from the same systematic input analysis as any other testing, but the input space is more structured: path parameters, query parameters, headers, and request bodies — each with their own validation rules and boundary conditions. This post applies BVA and equivalence partitioning specifically to REST API inputs. The
Database Testing
Database testing has its own equivalence partition structure driven by database constraints, SQL semantics, and the specific behaviors of NULL, type boundaries, and referential integrity. This post covers how to apply BVA and EP to database layer testing specifically. Database Column Constraints as Partition Sources Every column constraint defines partitions:
Test Design
Boundary value analysis (BVA) isn't a single technique — it's a family of related methods with different coverage philosophies. The version you learned in your testing certification is probably 2-point BVA: test at the boundary and just inside it. But 3-point BVA, robust BVA, and
Black-Box Testing
Black-box testing has seven or eight primary techniques. Knowing each individually is useful. Knowing which to apply to which problem is the skill that makes tests actually effective. This guide maps test scenarios to the techniques that produce the highest-value test cases for each. The Techniques A brief
Testing
Testing every possible combination of input parameters is mathematically straightforward and practically impossible. A feature with 10 parameters, each taking 5 values, has 5¹⁰ = nearly 10 million combinations. No team tests that. But most bugs are not caused by exotic 10-way interactions — they are caused by pairs or triples