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by tomjakubowski
4071 days ago
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I've never seen anyone claim that types (even a very strong type system like Haskell or Rust) mean you don't have to write tests. They just mean you don't have to write the very silly tests you would otherwise have to to feel secure in a dynamically typed language. |
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If however you say, "hey, I seriously don't want to cover all the lines including say error messages", then in Python,
if error: print obj.name
...might be a problem because obj doesn't have a name; in C++,
if(error) cout << obj.name;
...might only blow up because obj is a null reference (which is what you get when you dereference the null pointer, in practice, even though null references aren't supposed to exist); and in a language with non-nullable pointers, the equivalent of the above can only blow up if printing the name (which is surely valid if obj is non-nullable and type-checks as having a name) somehow blows up, which for a string in a memory-safe language is very very unlikely.
So if you leave uncovered lines in your code which we all do then yes, the stricter the type system, the better your chances are, statistically, all else being equal (for instance, the number of lines being the same... which might not be the case.)
Overall the silly tests people sometimes write in dynamic languages are needless IMO and result from over-applying "TDD" or "unit testing" or some other buzzword and/or paranoia of someone coming from a statically typed language background. I personally think I have pretty much the same amount of tests regardless of the type system.