What is positive and negative testing? What is the difference and which one is more common?

Positive testing is the verification of the system with valid, expected data and scenarios. The goal is to ensure that the functionality works as intended.

Negative testing is the verification of the system's behavior with incorrect, unexpected, or boundary data to ensure that the system correctly handles errors and does not break.

The difference is that positive testing confirms correct operation, while negative testing confirms robustness and error handling.

Positive testing is more common as it covers the main functionality, but for a quality product, negative testing is also important.