Types [1] can only reason about categories of values, not about values. Tests and types do have an overlap, but the best option is both. Especially when combine

Types [1] can only reason about categories of values, not about values. Tests and types do have an overlap, but the best option is both. Especially when combined with fuzzing, types can exclude large number of cases, making it even more efficient at covering a huge range of code paths. [1] yeah, there are type systems like lean, coq that can do both, but the proving process is just currently not realistic for everyday applications