Implement UnusedArgument cop

[aishek]

First of all, I've implemented autocorrection, and I am not sure if it is better than just add errors to arguments.

And the second thing is the cop ignores the case when there is no resolve method at all.

What do you think?

Resolves #53

[DmitryTsepelev]

Good start! Please check out my comments below and let's make CI pass

[aishek]

Thanks for the comments! I've applied them, and also made the code backward compatible.

I am not sure if the following method if reliable enough:

def method_name(node)
  node.loc.keyword.end.resize(node.method_name.to_s.size + 1)
end

Util.args_begin won't work for me somehow.

[DmitryTsepelev]

Specs are still failing (because of my stupid suggestion mostly) and we have a number of rubocop offences 🙂

[aishek]

Ok, I fixed it all 🤞

[DmitryTsepelev]

LGTM, thank you!

[jgrau]

Was the loads: argument considered? I have this chunk of code in a mutation:

...
    argument :booking_id, String, loads: Types::BookingType

    def resolve(booking:)
      ...
    end
...

but that complains that it wants booking_id to be a keyword argument in the resolve method.

:)

[aishek]

Was the loads: argument considered?

No, it was not. I will fix it, thanks!

[aishek]

I've created the fix #65