Fix source maps for @imported sass files w/ sassc processor

lib/sprockets.rb

@@ -128,6 +128,7 @@ module Sprockets
   register_bundle_metadata_reducer '*/*', :data, proc { String.new("") }, :concat
   register_bundle_metadata_reducer 'application/javascript', :data, proc { String.new("") }, Utils.method(:concat_javascript_sources)
   register_bundle_metadata_reducer '*/*', :links, :+
+  register_bundle_metadata_reducer '*/*', :sources, proc { [] }, :+
   register_bundle_metadata_reducer '*/*', :map, SourceMapUtils.method(:concat_source_maps)
 
   require 'sprockets/closure_compressor'

lib/sprockets/path_utils.rb

@@ -113,6 +113,21 @@ def relative_path_from(start, dest)
       dest.relative_path_from(start).to_s
     end
 
+    # Public: Joins path to base path.
+    #
+    # base - Root path
+    # path - Extending path
+    #
+    # Example
+    #
+    #     join('base/path/', '../file.js')
+    #     # => 'base/file.js'
+    #
+    # Returns string path starting from base and ending at path
+    def join(base, path)
+      (Pathname.new(base) + path).to_s
+    end
+
     # Internal: Get relative path for root path and subpath.
     #
     # path    - String path

lib/sprockets/sass_processor.rb

@@ -100,11 +100,14 @@ def call(input)
 
     private
 
+    def expand_source(source, env)
+      uri, _ = env.resolve!(source, pipeline: :source)
+      env.load(uri).digest_path
+    end
+
     def expand_map_sources(mapping, env)
       mapping.each do |map|
-        uri, _ = env.resolve!(map[:source], pipeline: :source)
-        source_path = env.load(uri).digest_path
-        map[:source] = source_path
+        map[:source] = expand_source(map[:source], env)
       end
     end
 

lib/sprockets/sassc_processor.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 require 'sprockets/sass_processor'
+require 'sprockets/path_utils'
 require 'base64'
 
 module Sprockets
@@ -22,39 +23,42 @@ def call(input)
       options = engine_options(input, context)
       engine = Autoload::SassC::Engine.new(input[:data], options)
 
-      data = Utils.module_include(Autoload::SassC::Script::Functions, @functions) do
-        engine.render
+      css = Utils.module_include(Autoload::SassC::Script::Functions, @functions) do
+        engine.render.sub(/^\n^\/\*# sourceMappingURL=.*\*\/$/m, '')
       end
 
-      match_data = data.match(/(.*)\n\/\*# sourceMappingURL=data:application\/json;base64,(.+) \*\//m)
-      css, map = match_data[1], Base64.decode64(match_data[2])
+      map = SourceMapUtils.decode_json_source_map(engine.source_map)
+      sources = map['sources'].map do |s|
+        expand_source(PathUtils.join(File.dirname(input[:filename]), s), input[:environment])
+      end
+
+      map = map["mappings"].each do |m|
+        m[:source] = PathUtils.join(File.dirname(input[:filename]), m[:source])
+      end
 
       map = SourceMapUtils.combine_source_maps(
         input[:metadata][:map],
-        change_source(SourceMapUtils.decode_json_source_map(map)["mappings"], input[:source_path])
+        expand_map_sources(map, input[:environment])
       )
 
       engine.dependencies.each do |dependency|
         context.metadata[:dependencies] << URIUtils.build_file_digest_uri(dependency.filename)
       end
 
-      context.metadata.merge(data: css, map: map)
+      context.metadata.merge(data: css, map: map, sources: sources)
     end
 
     private
 
-    def change_source(mappings, source)
-      mappings.each { |m| m[:source] = source }
-    end
-
     def engine_options(input, context)
       merge_options({
         filename: input[:filename],
         syntax: self.class.syntax,
         load_paths: input[:environment].paths,
         importer: @importer_class,
-        source_map_embed: true,
-        source_map_file: '.',
+        source_map_contents: true,
+        source_map_file: "#{input[:filename]}.map",
+        omit_source_map_url: true,
         sprockets: {
           context: context,
           environment: input[:environment],

lib/sprockets/source_map_processor.rb

@@ -17,9 +17,10 @@ def self.call(input)
 
       env = input[:environment]
 
-      uri, _ = env.resolve!(input[:filename], accept: accept)
-      asset  = env.load(uri)
-      map    = asset.metadata[:map] || []
+      uri, _  = env.resolve!(input[:filename], accept: accept)
+      asset   = env.load(uri)
+      map     = asset.metadata[:map] || []
+      sources = asset.metadata[:sources]
 
       # TODO: Because of the default piplene hack we have to apply dependencies
       #       from compiled asset to the source map, otherwise the source map cache
@@ -39,7 +40,7 @@ def self.call(input)
         links << uri
       end
 
-      json = env.encode_json_source_map(map, filename: asset.logical_path)
+      json = env.encode_json_source_map(map, sources: sources, filename: asset.logical_path)
 
       { data: json, links: links, dependencies: dependencies }
     end

lib/sprockets/source_map_utils.rb

@@ -140,7 +140,8 @@ def encode_json_source_map(mappings, sources: nil, names: nil, filename: nil)
         mappings.each do |m|
           m[:source] = PathUtils.relative_path_from(filename, m[:source])
         end if filename
-        sources ||= mappings.map { |m| m[:source] }.uniq.compact
+        sources = sources.map { |s| PathUtils.relative_path_from(filename, s) } if filename && sources
+        sources = (Array(sources) + mappings.map { |m| m[:source] }).uniq.compact
         names   ||= mappings.map { |m| m[:name] }.uniq.compact
         mappings = encode_vlq_mappings(mappings, sources: sources, names: names)
       else

sprockets.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rack-test", "~> 0.6"
   s.add_development_dependency "rake", "~> 10.0"
   s.add_development_dependency "sass", "~> 3.4"
-  s.add_development_dependency "sassc", "~> 1.7"
+  s.add_development_dependency "sassc", ">= 1.10.1", "< 2.0"
   s.add_development_dependency "uglifier", "~> 2.3"
   s.add_development_dependency "yui-compressor", "~> 0.12"
   s.add_development_dependency "zopfli", "~> 0.0.4"

test/test_source_maps.rb

@@ -295,4 +295,39 @@ def setup
       "names"    => []
     }, map)
   end
+
+  test "compile scss source map with imported dependencies" do
+    asset = silence_warnings do
+      @env.find_asset("sass/with-import.css")
+    end
+    assert asset
+    assert_equal fixture_path('source-maps/sass/with-import.scss'), asset.filename
+    assert_equal "text/css", asset.content_type
+
+    assert_match "body {\n  color: red; }", asset.source
+
+    asset = silence_warnings do
+      @env.find_asset("sass/with-import.css.map")
+    end
+    assert asset
+    assert_equal fixture_path('source-maps/sass/with-import.scss'), asset.filename
+    assert_equal "sass/with-import.css.map", asset.logical_path
+    assert_equal "application/css-sourcemap+json", asset.content_type
+    assert_equal [
+      "file://#{fixture_path_for_uri('source-maps/sass/_imported.scss')}?type=text/scss&pipeline=source",
+      "file://#{fixture_path_for_uri('source-maps/sass/with-import.scss')}?type=text/scss&pipeline=source"
+    ], normalize_uris(asset.links)
+
+    assert map = JSON.parse(asset.source)
+    assert_equal({
+      "version" => 3,
+      "file" => "sass/with-import.css",
+      "mappings" => "ACAA,AAAA,IAAI,CAAC;EAAE,KAAK,EAAE,GAAI,GAAI;;ADEtB,AAAA,GAAG,CAAC;EAAE,KAAK,EAAE,IAAK,GAAI",
+      "sources" => [
+        "with-import.source-5d53742ba113ac26396986bf14ab5c7e19ef193e494d5d868a9362e3e057cb26.scss",
+        "_imported.source-9767e91e9d4b0334e59a1d389e9801bc6a2c5c4a5500a3c2c7915687965b2c16.scss"
+      ],
+      "names" => []
+    }, map)
+  end
 end