What does test quality mean? Please tell us more.

Test quality is a set of characteristics that determine how effective and useful tests are for ensuring code reliability. Important aspects of test quality:

• Code coverage — how much of the code is tested by tests. But it's not just about quantity, but also the quality of coverage.
• Reliability — tests should be deterministic, not giving false positives or negatives.
• Maintainability — tests should be understandable and easily updatable when code changes.
• Performance — tests should run quickly so as not to slow down the development process.
• Isolation — tests should be independent of each other and not depend on external factors.
• Relevance — tests should verify real scenarios and business logic, not implementation details.

For example, unit tests should cover individual methods and classes, while integration tests should verify interactions between components. Good tests help quickly identify errors and facilitate refactoring.