Add test for sass/libsass#2786

[glebm]

Tests for sass/libsass#2786 fixed by sass/libsass#2860

[skip libsass]

[nex3]

I know the style guide hasn't officially landed yet, but it's still a good idea to follow it for new specs.

[glebm]

@nex3 Reading it now, is there anything in particular that stands out?

[glebm]

Read the style guide, should this then be: error/input.scss?

[glebm]

The style guide says "use dart sass output as canonical" but here Ruby and libsass have a much better error message. I've left a question on the style guide about this.

[glebm]

@nex3 [skip libsass] didn't seem to work here

[nex3]

Reading it now, is there anything in particular that stands out?

• Specs should be organized by which part of the language they're testing (this is currently in the README rather than the style guide, but it should probably be in the latter). This spec should go in spec/directives/supports/error/syntax (the HRX should be spec/directives/supports.hrx for now).

• Dart Sass's output should be the default.

• Placeholders should be single-letter names (so, (foo: bar) should be (a: b)).

• There isn't a styleguide rule for using one-line rules when they have no children, but there should be.

[skip libsass] didn't seem to work here

Oh, I thought you were a repo collaborator, but I guess not. It's a lot flakier for non-collaborators because they don't have access to the encrypted @sassbot GitHub credentials to read the commit message. I've sent you an invite to the sass-spec team.

[glebm]

Specs should be organized by which part of the language they're testing (this is currently in the README rather than the style guide, but it should probably be in the latter)

+1, everything a contributors need to know before submitting a new spec should be in one place.

Oh, I thought you were a repo collaborator, but I guess not

The mechanism in the libsass repo works even without that but I guess it uses public GitHub API (which may run out of quota with lots of PRs).

[glebm]

Thanks for the detailed feedback, I've addressed all the comments.