Fix UnnecessaryParentReference with multiple parent refs

The `UnnecessaryParentReference` linter would incorrectly report lints
for cases like the following:

    p {
      & + & { ... }
    }

In these situations, the first ampersand is required, since if you wrote
something like this:

    p {
      + & { ... }
    }

...the Sass compiler would produce the following invalid CSS:

    + p { ... }

Fix the problem by detecting if there are multiple ampersand references
in the sequence and ignoring it if that is the case.

Change-Id: Ica6042785883e3ed1c76d24dd8a25da5899bdfda
Reviewed-on: http://gerrit.causes.com/41625
Tested-by: jenkins <[email protected]>
Reviewed-by: Shane da Silva <[email protected]>

CHANGELOG.md

@@ -6,6 +6,8 @@
 * Add linting of `@include` and `@if`/`@else` blocks in `PropertySortOrder`
 * Fix `HexValidation` bug incorrectly reporting lints for 8 character hex
   codes in Microsoft `filter` property
+* Fix `UnnecessaryParentReference` incorrectly reporting lints for nested
+  selectors with more than one parent reference
 
 ## 0.26.2
 

lib/scss_lint/linter/unnecessary_parent_reference.rb

@@ -12,6 +12,12 @@ def visit_comma_sequence(comma_sequence)
     def visit_sequence(sequence)
       return unless sequence_starts_with_parent?(sequence.members.first)
 
+      # Allow sequences that contain multiple parent references, e.g.
+      # element {
+      #   & + & { ... }
+      # }
+      return if sequence.members[1..-1].any? { |ss| sequence_starts_with_parent?(ss) }
+
       # Special case: allow an isolated parent to appear if it is part of a
       # comma sequence of more than one sequence, as this could be used to DRY
       # up code.

spec/scss_lint/linter/unnecessary_parent_reference_spec.rb

@@ -41,6 +41,17 @@
     it { should_not report_lint }
   end
 
+  context 'when an ampersand precedes a sibling operator' do
+    let(:css) { <<-CSS }
+      p {
+        & + & {}
+        & ~ & {}
+      }
+    CSS
+
+    it { should_not report_lint }
+  end
+
   context 'when an amperand is used in a comma sequence to DRY up code' do
     let(:css) { <<-CSS }
       p {