Tell about your experience with test design techniques.

• Equivalence Partitioning: Dividing input data into equivalence classes. Testing only one representative from each class, assuming all values in the class are processed similarly by the system. Reduces the number of test cases with high confidence in coverage.
• Boundary Value Analysis: Testing values at the edges of each equivalence class. Usually the minimum, maximum, and values just around them. Errors often occur here.
• Decision Tables: Used for testing functionality where the system's behavior depends on a combination of conditions. Each row represents a unique combination of conditions and the expected result. Ensures complete coverage of combinations.
• State Transition Testing: Applied to systems with a finite number of states and transitions between them. Building a state diagram and testing transitions, invalid transitions, and cyclic transitions. Effective for testing user interfaces and workflows.
• Use Cases: Describes user interactions with the system to achieve a specific goal. Test cases are based on the main successful scenario steps and alternative paths (with errors or other outcomes). Helps test the system from the end-user perspective.
• Pairwise Testing: Used for systems with many parameters when testing all combinations is not feasible. Ensures that every pair of parameters is tested together at least once. Reduces the number of test cases compared to full combinatorial testing.

In practice, I often combine these techniques. For example, after equivalence partitioning and boundary value analysis, I might use decision tables to cover boundary value or system state combinations. For automation, I apply techniques to determine the optimal set of test data and sequences of actions.