What is test coverage?
Test coverage quantifies how thoroughly you've tested your software. It measures what percentage of your code executes during tests and how many requirements you've verified. While high coverage doesn't guarantee quality, it helps identify testing gaps.
Do you have any examples of test coverage?
Let's look at a login feature as an example. Coverage metrics might show that your tests:
- Verify successful login with valid credentials
- Check password validation rules
- Test the "forgot password" flow
- Validate error messages for incorrect inputs
- Exercise session timeout handling
Together, these test cases achieve 90% coverage of the login module's code, though some edge cases remain untested.
Why is test coverage important?
Test coverage reveals blind spots where bugs could hide and gives you data to discuss testing progress with stakeholders. Higher coverage typically means lower risk, as you've verified more of your system's behavior. When coverage drops after code changes, you know you need additional tests.
What are the challenges with test coverage?
Coverage metrics can be misleading. High percentages might hide shallow tests that don't validate behavior effectively. Complex features like concurrent operations are difficult to cover completely. Focus on balancing coverage goals with test quality, prioritizing critical business logic over perfect coverage.
Remember that some code paths matter more than others—comprehensive testing of your core features beats 100% coverage of simple utility functions.
Remember that some code paths matter more than others—comprehensive testing of your core features beats 100% coverage of simple utility functions.
