I omitted them because the test contexts provide all the necessary information.
That's only true because there are currently only two places calling this though; it doesn't seem like something that would scale well.
I suppose I don't see a need for it to scale well. If we have more tests for signature elements they can be added to the same function.
And, well, in general I think putting that information in the test context is just nicer than trying to manipulate the line number. I've made the change anyway here because I don't really want to hold up this bikeshedding (or argue with the maintainer), but I would like to express a preference to use test contexts in lieu of line number manipulation in cases like this.