Best Practice: Unit test coverage vs. in-method sanity checks [duplicate]

This question already has an answer here: Code Coverage or Test Brevity? (1 answer) Closed last year. I have a code-coverage requirement of of a certain percentage, and face the following tradeoff: Should I sacrifice in-method sanity checks and error handling for ease of (unit-) testability? Lets consider two variants of a simple method addAndSquare.…