Code coverage measures how much of the codebase is executed when tests run. It is commonly used to understand which parts of an application are touched by tests, but it should not be confused with a guarantee of correctness or robustness.
Line coverage, branch coverage, and condition coverage each provide different insights into test reach. High numbers can indicate that tests exercise many paths, but they do not ensure that those paths are validated with meaningful assertions. A test can execute code without verifying outcomes, leading to a false sense of confidence.
Code coverage is most useful when viewed as a directional metric. Gaps in coverage can highlight untested logic, error handling, or edge cases that deserve attention. Tracking coverage trends over time is often more valuable than chasing a fixed percentage, as sudden drops or unexpected spikes may signal deeper issues in test design.
Overemphasis on code coverage targets can encourage superficial tests written solely to increase numbers. This approach adds maintenance overhead without improving reliability. Strong tests focus on validating behavior and business rules, using coverage as a supporting tool rather than a primary goal.
When combined with thoughtful test design and regular review, code coverage helps teams understand where their tests reach and where risks remain. Used correctly, it informs better testing decisions instead of serving as a checkbox for quality.