by Bernard Murphy

Coverage analysis is how you answer the question “have I tested enough?” You need some way to quantify the completeness of our testing; coverage is how you do that. Right out of the gate this is a bit deceptive. To truly cover a design our tests would need to cover every accessible state and state transition. The complexity of that task routinely invokes comparisons with the number of protons in the universe so instead, you use proxies for coverage. Touching every line in the RTL, exercising every branch, every function, every assertion, and so on. Each is a far cry from exhaustive coverage., but as heuristics, they work surprisingly well.

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