Fix the expected output for str-slice().

[nex3]

No description provided.

[xzyfer]

I'm not sure I completely follow the issue. Can you please confirm what the output of the following should be?

a {
  test-11: str-slice('aöc', 0, -3);
  test-12: str-slice('aöc', 1, -3);

  test-16: str-slice('aöc', 0, -4);
  test-17: str-slice('aöc', 1, -4);

  test-18: str-slice('aöc', 2, -4);
  test-19: str-slice('aöc', 3, -4);
}

From my understanding they should all return "", am I mistaken?

[nex3]

@xzyfer str-slice('aöc', 0, -3) should both return "a", because the $end-at parameter is inclusive and points to the third-from-last character, a. The same is true for str-slice('aöc', 1, -3), since indices are 1-based and so the index 1 also points at a. The others should all return "".

[xzyfer]

Sorry I'm not clear why these both return a.

test-11: str-slice('aöc', 0, -3);
test-16: str-slice('aöc', 0, -4);

See https://github.com/sass/sass-spec/pull/997/files#diff-2a1fce6f95db3f518285362f272d8e61R18

Seems to run contradictory to your previous comment.