Line Coverage
Did we execute this line? Useful but weak. A project can have 90% line coverage while mutation testing finds large numbers of mutations that tests don’t detect.
Coverage measures execution. An assertion measures correctness. These are not the same thing.
Sensor properties
| Property | Value |
|---|---|
| Oracle strength | Low — execution is not correctness |
| Independence | Low — same author writes tests |
| Scope | Line-level |
| Feedback latency | Seconds |
| Actionability | Guiding — shows which lines weren’t executed |
| Type | Predictive |
What it cannot detect
Whether the code that executed was actually asserted on. A line can execute without any test verifying its output. This is why coverage alone is a weak oracle.