Exactly, or to put it another way: you are not forced to cover the code you didn't write; in this case, the non-zero check before the division. Mix this with u

Exactly, or to put it another way: you are not forced to cover the code you didn't write; in this case, the non-zero check before the division. Mix this with unchecked exceptions, mocking of any real-world interaction that will generate errors in productions, and testing becomes a cargo-cult of quality.