Question: Why does t.doesNotThrow have three arguments?

[des-des]

I do not understand why t.doesNotThrow(fn, expected, msg) has three arguments. It seems like the second argument, expected, is actually used as the message: https://github.com/substack/tape/blob/master/lib/test.js#L476.

Why doesn't the function just have the signature t.doesNotThrow(fn, message)?

[ljharb]

It's an if - if you pass an error instance, it checks the type of the error as well.

It's meant to mirror the assert API.

[des-des]

@ljharb

I do not see how we can check type of error which has not been thrown. Sorry, I might be missing something.

It seems the in the API for assert doesNotThrow only takes two arguments https://www.npmjs.com/package/assert#assertdoesnotthrowblock-message. But might be looking in the wrong place.

[ljharb]

@des-des that package is not the core module assert, it's something else that nobody can ever actually require in node. You're looking for https://nodejs.org/api/assert.html#assert_assert_doesnotthrow_block_error_message which also explains what the argument is used for. "does not throw a TypeError" is not the same as "does not throw anything at all" - something that throws a RangeError, for example, fails the latter but passes the former.