Configure Sass to load from theme-gem if possible

lib/jekyll/converters/scss.rb

@@ -79,8 +79,10 @@ def sass_dir_relative_to_site_source
         Jekyll.sanitized_path(site_source, sass_dir)
       end
 
+      # rubocop:disable Metrics/AbcSize
       def sass_load_paths
         paths = user_sass_load_paths + [sass_dir_relative_to_site_source]
+        paths << site.theme.sass_path if site.theme&.sass_path
 
         if safe?
           # Sanitize paths to prevent any attack vectors (.e.g. `/**/*`)
@@ -103,6 +105,7 @@ def sass_load_paths
 
         paths.select { |path| File.directory?(path) }
       end
+      # rubocop:enable Metrics/AbcSize
 
       def allow_caching?
         !safe?
@@ -130,8 +133,12 @@ def convert(content)
 
       private
 
+      def site
+        @site ||= Jekyll.sites.last
+      end
+
       def site_source
-        @site_source ||= File.expand_path(@config["source"]).freeze
+        @site_source ||= site.source
       end
     end
   end

spec/sass_converter_spec.rb

@@ -31,7 +31,9 @@ def compressed(content)
   end
 
   def converter(overrides = {})
-    Jekyll::Converters::Sass.new(site_configuration("sass" => overrides))
+    sass_converter_instance(site).dup.tap do |obj|
+      obj.instance_variable_get(:@config)["sass"] = overrides
+    end
   end
 
   context "matching file extensions" do
@@ -46,7 +48,7 @@ def converter(overrides = {})
 
   context "converting sass" do
     it "produces CSS" do
-      expect(converter.convert(content)).to eql(compressed(css_output))
+      expect(converter.convert(content)).to eql(css_output)
     end
 
     it "includes the syntax error line in the syntax error message" do

spec/scss_converter_spec.rb

@@ -34,7 +34,9 @@ def compressed(content)
   end
 
   def converter(overrides = {})
-    Jekyll::Converters::Scss.new(site_configuration("sass" => overrides))
+    scss_converter_instance(site).dup.tap do |obj|
+      obj.instance_variable_get(:@config)["sass"] = overrides
+    end
   end
 
   context "matching file extensions" do
@@ -118,7 +120,7 @@ def converter(overrides = {})
 
   context "converting SCSS" do
     it "produces CSS" do
-      expect(converter.convert(content)).to eql(compressed(css_output))
+      expect(converter.convert(content)).to eql(css_output)
     end
 
     it "includes the syntax error line in the syntax error message" do

spec/spec_helper.rb

@@ -46,10 +46,10 @@ def make_site(config)
   end
 
   def scss_converter_instance(site)
-    if Jekyll::VERSION >= "3.0"
-      site.find_converter_instance(Jekyll::Converters::Scss)
-    else
-      site.getConverterImpl(Jekyll::Converters::Scss)
-    end
+    site.find_converter_instance(Jekyll::Converters::Scss)
+  end
+
+  def sass_converter_instance(site)
+    site.find_converter_instance(Jekyll::Converters::Sass)
   end
 end