What test design techniques do you like the most?

I like techniques that provide effective coverage and help identify defects early:

• Equivalence Partitioning: Allows significantly reducing the number of test cases by grouping input data based on expected behavior. This saves time and resources while maintaining high test coverage for various data categories.
• Boundary Value Analysis: An addition to equivalence classes. Used for testing values at the boundaries of ranges, where the likelihood of errors is higher. I pay special attention to this technique.
• Decision Tables: Great for testing complex logic dependent on multiple conditions. Visual representation of all possible condition combinations and corresponding actions makes them understandable and helps ensure full scenario coverage.
• State Transition Testing: Effective for testing systems whose behavior depends on previous events or current state. Ensures that the system transitions correctly between states and responds to events.

The choice of a specific technique always depends on the specifics of the functionality being tested. I often combine these approaches for maximum efficiency. For example, using equivalence classes and boundary value analysis for input data, and decision tables for testing business logic.