Tools for quality checks of test-bench


are there tools which check quality of test-bench/regressions?
i remember there was once a tool which manipulates automatically verilog lines and checks if regression had caught them (catching holes in tests, checkers switched off etc.)


In reply to Noam Elbaum:

The very first metric of testbench quality is code coverage (including toggle coverage). You did not test what you did not exercise.

What you are referring to is called fault simulation analysis. This is an older technology used in manufacturing/testing that is now being applied to test quality. It is one aspect of emerging Functional Safety standards now actively under development. You might want to read more about it here: