Support missing channels across the embedded protocol (#246)

Author: ntkme

lib/sass/compiler/host/protofier.rb

@@ -112,13 +112,14 @@ def from_proto(proto)
           when :number
             Number.from_proto(obj)
           when :color
+            obj.to_s # TODO: https://github.com/protocolbuffers/protobuf/issues/18807
             Sass::Value::Color.send(
               :for_space,
               obj.space,
-              obj.channel1,
-              obj.channel2,
-              obj.channel3,
-              obj.alpha
+              obj.has_channel1? ? obj.channel1 : nil,
+              obj.has_channel2? ? obj.channel2 : nil,
+              obj.has_channel3? ? obj.channel3 : nil,
+              obj.has_alpha? ? obj.alpha : nil
             )
           when :argument_list
             Sass::Value::ArgumentList.new(

spec/sass_proto_spec.rb

@@ -63,9 +63,9 @@ def remote_eq(lhs, rhs)
                                                                             ])
                                              ]),
     __LINE__ => Sass::Value::Calculation.clamp(Sass::Value::String.new('var(--clamp)', quoted: false)),
-    __LINE__ => Sass::Value::Color.new(red: 0, green: 0, blue: 0, alpha: 1),
-    __LINE__ => Sass::Value::Color.new(hue: 0, saturation: 0, lightness: 0, alpha: 1),
-    __LINE__ => Sass::Value::Color.new(hue: 0, whiteness: 0, blackness: 0, alpha: 1),
+    __LINE__ => Sass::Value::Color.new(red: 0.1, green: 0.2, blue: nil, alpha: 1, space: 'rgb'),
+    __LINE__ => Sass::Value::Color.new(hue: 0.4, saturation: nil, lightness: 0.6, alpha: 1, space: 'hsl'),
+    __LINE__ => Sass::Value::Color.new(hue: nil, whiteness: 0.8, blackness: 0.9, alpha: 1, space: 'hwb'),
     __LINE__ => Sass::Value::List.new,
     __LINE__ => Sass::Value::List.new([Sass::Value::String.new('a')]),
     __LINE__ => Sass::Value::List.new([Sass::Value::String.new('a')], separator: ','),