Fix signature order cop when we have an incomplete call

[vinistock]

While the developer is typing, we might have no syntax errors, but an incomplete signature still (e.g.: sig { params(a: Integer).voi }).

This causes the cop to break, which is surfaced by the Ruby LSP basically every single time someone is typing a signature.

[andyw8]

I wonder if there's a generic way we could detect this kind of issue, since I believe we've seen similar in the past. You could build up the fixture character by character and run the cop against each version. It would be slow, but it could be a periodic check which runs once a week or so.

[vinistock]

Yeah, it's worth investigating techniques to find these. The only issue with going character by character is that it might not cover all possible scenarios. For example

# This error
params().

# Is different than this
params()v

# Which is also different than
params.v

Depending on autocompletion and auto-closing brackets, there might be states that aren't captured by going char by char. At the same time, it produces a lot of redundant tests since

params().v
params().vo
params().voi

are all the same test case for this particular scenario. It might be worth connecting with the YARP team and asking how they are coming up with partially complete code examples.