Add ThemeAssetsReader which reads assets from a theme

.rubocop.yml

@@ -16,7 +16,7 @@ Lint/UnreachableCode:
 Lint/UselessAccessModifier:
   Enabled: false
 Metrics/AbcSize:
-  Max: 20
+  Max: 21
 Metrics/ClassLength:
   Exclude:
     - !ruby/regexp /features\/.*.rb$/

features/theme.feature

@@ -17,7 +17,7 @@ Feature: Writing themes
   Scenario: A theme with SCSS
     Given I have a configuration file with "theme" set to "test-theme"
     And I have a css directory
-    And I have a "css/main.scss" page that contains "@import 'style';"
+    And I have a "css/main.scss" page that contains "@import 'test-theme-black';"
     When I run jekyll build
     Then I should get a zero exit status
     And the _site directory should exist

lib/jekyll.rb

@@ -55,6 +55,7 @@ module Jekyll
   autoload :PostReader,          "jekyll/readers/post_reader"
   autoload :PageReader,          "jekyll/readers/page_reader"
   autoload :StaticFileReader,    "jekyll/readers/static_file_reader"
+  autoload :ThemeAssetsReader,   "jekyll/readers/theme_assets_reader"
   autoload :LogAdapter,          "jekyll/log_adapter"
   autoload :Page,                "jekyll/page"
   autoload :PluginManager,       "jekyll/plugin_manager"

lib/jekyll/page.rb

@@ -40,7 +40,11 @@ def initialize(site, base, dir, name)
       @base = base
       @dir  = dir
       @name = name
-      @path = site.in_source_dir(base, dir, name)
+      @path = if site.in_theme_dir(base) == base # we're in a theme
+                site.in_theme_dir(base, dir, name)
+              else
+                site.in_source_dir(base, dir, name)
+              end
 
       process(name)
       read_yaml(File.join(base, dir), name)

lib/jekyll/reader.rb

@@ -18,6 +18,7 @@ def read
       sort_files!
       @site.data = DataReader.new(site).read(site.config["data_dir"])
       CollectionReader.new(site).read
+      ThemeAssetsReader.new(site).read
     end
 
     # Sorts posts, pages, and static files.

lib/jekyll/readers/theme_assets_reader.rb

@@ -0,0 +1,47 @@
+module Jekyll
+  class ThemeAssetsReader
+    attr_reader :site
+    def initialize(site)
+      @site = site
+    end
+
+    def read
+      return unless site.theme && site.theme.assets_path
+
+      Find.find(site.theme.assets_path) do |path|
+        next if File.directory?(path)
+        if File.symlink?(path)
+          Jekyll.logger.warn "Theme reader:", "Ignored symlinked asset: #{path}"
+        else
+          read_theme_asset(path)
+        end
+      end
+    end
+
+    private
+    def read_theme_asset(path)
+      base = site.theme.root
+      dir = File.dirname(path.sub("#{site.theme.root}/", ""))
+      name = File.basename(path)
+
+      if Utils.has_yaml_header?(path)
+        append_unless_exists site.pages,
+          Jekyll::Page.new(site, base, dir, name)
+      else
+        append_unless_exists site.static_files,
+          Jekyll::StaticFile.new(site, base, dir, name)
+      end
+    end
+
+    def append_unless_exists(haystack, new_item)
+      if haystack.any? { |file| file.relative_path == new_item.relative_path }
+        Jekyll.logger.debug "Theme:",
+          "Ignoring #{new_item.relative_path} in theme due to existing file " \
+          "with that path in site."
+        return
+      end
+
+      haystack << new_item
+    end
+  end
+end

lib/jekyll/theme.rb

@@ -18,15 +18,19 @@ def root
     end
 
     def includes_path
-      path_for :includes
+      path_for "_includes".freeze
     end
 
     def layouts_path
-      path_for :layouts
+      path_for "_layouts".freeze
     end
 
     def sass_path
-      path_for :sass
+      path_for "_sass".freeze
+    end
+
+    def assets_path
+      path_for "assets".freeze
     end
 
     def configure_sass
@@ -43,7 +47,7 @@ def path_for(folder)
     end
 
     def realpath_for(folder)
-      File.realpath(Jekyll.sanitized_path(root, "_#{folder}"))
+      File.realpath(Jekyll.sanitized_path(root, folder.to_s))
     rescue Errno::ENOENT, Errno::EACCES, Errno::ELOOP
       nil
     end

lib/jekyll/theme_builder.rb

@@ -1,6 +1,6 @@
 class Jekyll::ThemeBuilder
   SCAFFOLD_DIRECTORIES = %w(
-    _layouts _includes _sass
+    assets _layouts _includes _sass
   ).freeze
 
   attr_reader :name, :path, :code_of_conduct

site/_docs/themes.md

@@ -27,6 +27,7 @@ Jekyll themes set default layouts, includes, and stylesheets, that can be overri
 
 Jekyll will look first to your site's content, before looking to the theme's defaults, for any requested file in the following folders:
 
+* `/assets`
 * `/_layouts`
 * `/_includes`
 * `/_sass`
@@ -68,6 +69,12 @@ Theme layouts and includes work just like they work in any Jekyll site. Place la
 
 For example, if your theme has a `/_layouts/page.html` file, and a page has `layout: page` in its YAML front matter, Jekyll will first look to the site's `_layouts` folder for a the `page` layout, and if none exists, will use your theme's `page` layout.
 
+### Assets
+
+Any file in `/assets` will be copied over to the user's site upon build unless they have a file with the same relative path. You may ship any kind of asset here: SCSS, an image, a webfont, etc. These files behave just like pages and static files in Jekyll: if the file has [YAML front matter]({{ site.baseurl }}/docs/frontmatter/) at the top, then it will be rendered. If it does not have YAML front matter, it will simply be copied over into the resulting site. This allows theme creators to ship a default `/assets/styles.scss` file which their layouts can depend on as `/assets/styles.css`.
+
+All files in `/assets` will be output into the compiled site in the `/assets` folder just as you'd expect from using Jekyll on your sites.
+
 ### Stylesheets
 
 Your theme's stylesheets should be placed in your theme's `/_sass` folder, again, just as you would when authoring a Jekyll site. Your theme's styles can be included in the user's stylesheet using the `@import` directive.

test/fixtures/test-theme/_sass/test-theme-red.scss

@@ -0,0 +1,3 @@
+.sample {
+  color: red;
+}

test/fixtures/test-theme/assets/application.coffee

@@ -0,0 +1,3 @@
+---
+---
+alert "From your theme."

test/fixtures/test-theme/assets/img/another-logo.png

@@ -0,0 +1 @@
+logo.png

test/fixtures/test-theme/assets/style.scss

@@ -0,0 +1,3 @@
+---
+---
+@import "test-theme-{{ site.theme-color | default: "red" }}";

test/source/assets/application.coffee

@@ -0,0 +1,3 @@
+---
+---
+alert "From your site."

test/test_filters.rb

@@ -475,7 +475,7 @@ def to_liquid
               g["items"].is_a?(Array),
               "The list of grouped items for '' is not an Array."
             )
-            assert_equal 14, g["items"].size
+            assert_equal 15, g["items"].size
           end
         end
       end

test/test_site.rb

@@ -180,6 +180,7 @@ def generate(site)
         %#\ +.md
         .htaccess
         about.html
+        application.coffee
         bar.html
         coffeescript.coffee
         contacts.html

test/test_theme.rb

@@ -34,16 +34,16 @@ def setup
   end
 
   context "path generation" do
-    [:layouts, :includes, :sass].each do |folder|
+    [:assets, :_layouts, :_includes, :_sass].each do |folder|
       should "know the #{folder} path" do
-        expected = File.expand_path("_#{folder}", @expected_root)
-        assert_equal expected, @theme.public_send("#{folder}_path")
+        expected = File.expand_path(folder.to_s, @expected_root)
+        assert_equal expected, @theme.public_send("#{folder.to_s.tr("_", "")}_path")
       end
     end
 
     should "generate folder paths" do
       expected = File.expand_path("./_sass", @expected_root)
-      assert_equal expected, @theme.send(:path_for, :sass)
+      assert_equal expected, @theme.send(:path_for, :_sass)
     end
 
     should "not allow paths outside of the theme root" do
@@ -56,7 +56,7 @@ def setup
 
     should "return the resolved path when a symlink & resolved path exists" do
       expected = File.expand_path("./_layouts", @expected_root)
-      assert_equal expected, @theme.send(:path_for, :symlink)
+      assert_equal expected, @theme.send(:path_for, :_symlink)
     end
   end
 

test/test_theme_assets_reader.rb

@@ -0,0 +1,71 @@
+require "helper"
+
+class TestThemeAssetsReader < JekyllUnitTest
+  def setup
+    @site = fixture_site(
+      "theme"       => "test-theme",
+      "theme-color" => "black"
+    )
+    assert @site.theme
+  end
+
+  def assert_file_with_relative_path(haystack, relative_path)
+    assert haystack.any? { |f|
+      f.relative_path == relative_path
+    }, "Site should read in the #{relative_path} file, " \
+      "but it was not found in #{haystack.inspect}"
+  end
+
+  def refute_file_with_relative_path(haystack, relative_path)
+    refute haystack.any? { |f|
+      f.relative_path == relative_path
+    }, "Site should not have read in the #{relative_path} file, " \
+      "but it was found in #{haystack.inspect}"
+  end
+
+  context "with a valid theme" do
+    should "read all assets" do
+      @site.reset
+      ThemeAssetsReader.new(@site).read
+      assert_file_with_relative_path @site.static_files, "assets/img/logo.png"
+      assert_file_with_relative_path @site.pages, "assets/style.scss"
+    end
+
+    should "convert pages" do
+      @site.process
+
+      file = @site.pages.find { |f| f.relative_path == "assets/style.scss" }
+      refute_nil file
+      assert_equal @site.in_dest_dir("assets/style.css"), file.destination(@site.dest)
+      assert_includes file.output, ".sample {\n  color: black; }"
+    end
+
+    should "not overwrite site content with the same relative path" do
+      @site.reset
+      @site.read
+
+      file = @site.pages.find { |f| f.relative_path == "assets/application.coffee" }
+      refute_nil file
+      assert_includes file.content, "alert \"From your site.\""
+    end
+  end
+
+  context "with a valid theme without an assets dir" do
+    should "not read any assets" do
+      site = fixture_site("theme" => "test-theme")
+      allow(site.theme).to receive(:assets_path).and_return(nil)
+      ThemeAssetsReader.new(site).read
+      refute_file_with_relative_path site.static_files, "assets/img/logo.png"
+      refute_file_with_relative_path site.pages, "assets/style.scss"
+    end
+  end
+
+  context "with no theme" do
+    should "not read any assets" do
+      site = fixture_site("theme" => nil)
+      ThemeAssetsReader.new(site).read
+      refute_file_with_relative_path site.static_files, "assets/img/logo.png"
+      refute_file_with_relative_path site.pages, "assets/style.scss"
+    end
+  end
+end