Rake task check syntax in a Rails app.

gistfile1.txt

namespace :syntax do

  desc 'Checks the syntax of ERB files'
  task :erb do
    require 'action_view'
    puts "Start check ERB files: "

    errors = []
    Dir['app/views/**/*.erb'].each do |file|
      template = File.read(file)

      begin
        ActionView::Template::Handlers::Erubis \
          .new(template, :filename => file) \
          .result

        print '.'
      # ERB syntax errors.
      rescue SyntaxError => error
        print 'F'
        errors << error.message
      # Calls to undefined methods, etc. We only care about the syntax.
      rescue Exception => error
        print '.'
      end
    end

    if errors.blank?
      puts "\nERB OK!\n"
    else
      puts "\nErrors: \n"
      errors.each do |e|
        puts e
      end
    end
  end

  desc 'Checks the syntax of HAML files'
  task :haml do
    begin
      require 'haml'
      puts "Start check HAML files: "

      errors = []
      Dir['app/views/**/*.haml'].each do |file|
        template = File.read(file)

        begin
          Haml::Engine.new(template, :filename => file)

          print '.'
        rescue Haml::SyntaxError, Haml::Error => error
          line = error.backtrace[0].match(/(\d+)$/)[1]
          print 'F'
          errors << "#{file}: line ##{line}: #{error.message}"
        end
      end

      if errors.blank?
        puts "\nHAML OK!\n"
      else
        puts "\nErrors: \n"
        errors.each do |e|
          puts e
        end
      end
    rescue LoadError => e
    end
  end

  desc 'Checks the syntax of SLIM files'
  task :slim do
    begin
      require 'slim'
      puts "Start check SLIM files: "

      errors = []
      Dir['app/views/**/*.slim'].each do |file|
        begin
          Slim::Template.new(file)

          print '.'
        rescue Slim::Parser::SyntaxError => error
          line = error.backtrace[0].match(/(\d+)$/)[1]
          print 'F'
          errors << "#{file}: line ##{line}: #{error.message}"
        end
      end

      if errors.blank?
        puts "\nSLIM OK!\n"
      else
        puts "\nErrors: \n"
        errors.each do |e|
          puts e
        end
      end
    rescue LoadError => e
    end
  end

  desc 'Checks the syntax of YAML files'
  task :yaml do
    require 'yaml'
    puts "Start check YAML files: "

    errors = []
    Dir['./**/*.{yml,yaml}'].each do |file|
      begin
        YAML.load_file(file)

        print '.'
      rescue => error
        print 'F'
        errors << "#{file}: #{error.message}"
      end
    end

    if errors.blank?
      puts "\nYAML OK!\n"
    else
      puts "\nErrors: \n"
      errors.each do |e|
        puts e
      end
    end
  end

  desc 'Checks the syntax of ruby files'
  task :ruby do
    require 'open3'
    puts "Start check ruby files: "
    errors = []
    Dir['./**/*.rb'].each do |file|
      cmd = "ruby -c #{file} | grep 'syntax error'"
      Open3.popen3(cmd) do |stdin, stdout, stderr, wait_thr|
        msg = stderr.read
        if msg.blank?
          print '.'
        else
          trace_msg = msg.split("\n")[0]
          print "F"
          puts "\n#{trace_msg}\n"
          errors << trace_msg
        end
      end
    end

    if errors.blank?
      puts "\nRuby OK!\n"
    else
      puts "\nErrors: \n"
      errors.each do |e|
        puts e
      end
    end
  end
end

# desc 'Checks the syntax of various files'
task :syntax => ['syntax:erb', 'syntax:yaml', 'syntax:haml', 'syntax:slim', 'syntax:ruby']

# How run??
# rake syntax:erb syntax:ruby syntax:yaml syntax:haml syntax:slim
# rake syntax