Checking the syntax of various Ruby related files in a Rails project.

syntax.rake

namespace :syntax do
  desc 'Checks the syntax of ERB files'
  task :erb do
    require 'action_view'

    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
        puts 'F'
        puts error.message
        exit 1

      # Calls to undefined methods, etc. We only care about the syntax.
      rescue Exception => error
        print '.'
      end
    end

    puts
    puts 'ERB OK!'
  end

  desc 'Checks the syntax of HAML files'
  task :haml do
    require 'haml'

    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]

        puts 'F'
        puts "#{file}: line ##{line}: #{error.message}"
        exit 1
      end
    end

    puts
    puts 'HAML OK!'
  end

  desc 'Checks the syntax of YAML files'
  task :yaml do
    require 'yaml'

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

        print '.'
      rescue => error
        puts 'F'
        puts "#{file}: #{error.message}"
        exit 1
      end
    end

    puts
    puts 'YAML OK!'
  end
end

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