I don't think the number of arguments is what's interesting here; what I think is interesting (and worth calling out in the docstring) is that the method supports additional keyword args not named in what you passed to `with_keyword_argument`.  They have defaults so that should be OK as you've shown.

BTW, I think the doc string for the example above should be changed to:

``` ruby
it "passes if given all defined keyword arguments"
```