Add rake guides:lint task to raise error on broken anchor links

guides/Rakefile

@@ -23,12 +23,23 @@ namespace :guides do
     end
   end
 
-  desc "Lint guides, using `mdl`"
-  task :lint do
-    require "mdl"
-    all = Dir.glob("#{__dir__}/source/*.md")
-    files = all - Dir.glob("#{__dir__}/**/*_release_notes.md") # Ignore release notes
-    MarkdownLint.run files
+  desc "Lint guides, using `mdl` and check for broken links"
+  task lint: ["lint:check_links", "lint:mdl"]
+
+  namespace :lint do
+    desc "Check links in generated HTML guides"
+    task :check_links do
+      ENV["GUIDES_LINT"] = "1"
+      ruby "-Eutf-8:utf-8", "rails_guides.rb"
+    end
+
+    desc "Run mdl to check Markdown files for style guide violations and lint errors"
+    task :mdl do
+      require "mdl"
+      all = Dir.glob("#{__dir__}/source/*.md")
+      files = all - Dir.glob("#{__dir__}/**/*_release_notes.md") # Ignore release notes
+      MarkdownLint.run files
+    end
   end
 
   # Validate guides -------------------------------------------------------------------------

guides/rails_guides.rb

@@ -26,5 +26,6 @@
   only:      env_value["ONLY"],
   epub:      env_flag["EPUB"],
   language:  env_value["GUIDES_LANGUAGE"],
-  direction: env_value["DIRECTION"]
+  direction: env_value["DIRECTION"],
+  lint:      env_flag["GUIDES_LINT"]
 ).generate

guides/rails_guides/generator.rb

@@ -13,37 +13,52 @@
 require "rails_guides/markdown"
 require "rails_guides/helpers"
 require "rails_guides/epub"
+require "debug"
 
 module RailsGuides
   class Generator
     GUIDES_RE = /\.(?:erb|md)\z/
 
-    def initialize(edge:, version:, all:, only:, epub:, language:, direction: nil)
+    def initialize(edge:, version:, all:, only:, epub:, language:, direction: nil, lint:)
       @edge      = edge
       @version   = version
       @all       = all
       @only      = only
       @epub      = epub
       @language  = language
       @direction = direction || "ltr"
+      @lint = lint
+      @warnings = []
 
       if @epub
         register_special_mime_types
       end
 
       initialize_dirs
-      create_output_dir_if_needed
+      create_output_dir_if_needed if !dry_run?
       initialize_markdown_renderer
     end
 
     def generate
       generate_guides
-      process_scss
-      copy_assets
-      generate_epub if @epub
+
+      if @lint && @warnings.any?
+        puts "#{@warnings.join("\n")}"
+        exit 1
+      end
+
+      if !dry_run?
+        process_scss
+        copy_assets
+        generate_epub if @epub
+      end
     end
 
     private
+      def dry_run?
+        [@lint].any?
+      end
+
       def register_special_mime_types
         Mime::Type.register_alias("application/xml", :opf, %w(opf))
         Mime::Type.register_alias("application/xml", :ncx, %w(ncx))
@@ -168,12 +183,15 @@ def generate_guide(guide, output_file)
             epub:    @epub
           ).render(body)
 
-          warn_about_broken_links(result)
+          broken = warn_about_broken_links(result)
+          if broken.any?
+            @warnings << "[WARN] BROKEN LINK(s): #{guide}: #{broken.join(", ")}"
+          end
         end
 
         File.open(output_path, "w") do |f|
           f.write(result)
-        end
+        end if !dry_run?
       end
 
       def warn_about_broken_links(html)
@@ -199,13 +217,18 @@ def extract_anchors(html)
       end
 
       def check_fragment_identifiers(html, anchors)
+        broken_links = []
+
         html.scan(/<a\s+href="#([^"]+)/).flatten.each do |fragment_identifier|
           next if fragment_identifier == "mainCol" # in layout, jumps to some DIV
           unless anchors.member?(CGI.unescape(fragment_identifier))
             guess = DidYouMean::SpellChecker.new(dictionary: anchors).correct(fragment_identifier).first
             puts "*** BROKEN LINK: ##{fragment_identifier}, perhaps you meant ##{guess}."
+            broken_links << "##{fragment_identifier}"
           end
         end
+
+        broken_links
       end
   end
 end