allow one column data-table to be passed as parameter

[Fuud]

This pull-request allows values from one-column data-table to be passed as parameter. For example:

def "allow one column to be passed as parameter"(a) {
    expect:
    a == 3

    where:
    a | _
    3 | _
  }

[Fuud]

@alkemist @pniederw any comments?

[ldaley]

@Fuud I'm not sure this is preferable to the existing syntax.

def "allow one column to be passed as parameter"(a) {
    expect:
    a == 3

    where:
    a << [3]
  }

So my preference would be not to add this.

Thanks for taking the time on the contribution regardless. Peter might want this, so it's not over yet.

[pniederw]

@alkemist: The one-column syntax happens to work already, without Spock doing anything special to make it work. This PR makes it possible to use one-column syntax with an explicit argument list of the form (a) rather than (a, _), which kind of makes sense. Technically this is a breaking change, but it seems rather unlikely that any existing code would be using (a, _) instead of (). Hence I'm inclined to merge this.

[pniederw]

@Fuud Thanks for submitting the most subtle pull request ever. :-) I'll have a look at this soon.

[ldaley]

@pniederw then +1 on the merge.

[Fuud]

@alkemist @pniederw any progress?

[pniederw]

This is now merged. Thanks for your contribution.