Deprecation warning for auto-require of template engines

compat/helper.rb

@@ -1,10 +1,6 @@
 require 'rubygems'
 require 'mocha'
 
-require 'haml'
-require 'sass'
-require 'builder'
-
 # disable warnings in compat specs.
 $VERBOSE = nil
 

lib/sinatra/base.rb

@@ -223,19 +223,27 @@ module Sinatra
   #                 in the template
   module Templates
     def erb(template, options={}, locals={})
+      require_warn('ERB') unless defined?(::ERB)
+
       render :erb, template, options, locals
     end
 
     def haml(template, options={}, locals={})
+      require_warn('Haml') unless defined?(::Haml::Engine)
+
       render :haml, template, options, locals
     end
 
     def sass(template, options={}, locals={})
+      require_warn('Sass') unless defined?(::Sass::Engine)
+
       options[:layout] = false
       render :sass, template, options, locals
     end
 
     def builder(template=nil, options={}, locals={}, &block)
+      require_warn('Builder') unless defined?(::Builder)
+
       options, template = template, nil if template.is_a?(Hash)
       template = lambda { block } if template.nil?
       render :builder, template, options, locals
@@ -331,6 +339,11 @@ module Sinatra
       end
       xml.target!
     end
+
+    def require_warn(engine)
+      warn "Auto-require of #{engine} is deprecated; add require '#{engine}' to your app."
+      require engine.downcase
+    end
   end
 
   # Base class for all Sinatra applications and middleware.

test/builder_test.rb

@@ -1,4 +1,5 @@
 require File.dirname(__FILE__) + '/helper'
+require 'builder'
 
 class BuilderTest < Test::Unit::TestCase
   def builder_app(&block)

test/helper.rb

@@ -16,10 +16,6 @@ $LOAD_PATH.unshift libdir unless $LOAD_PATH.include?(libdir)
 require 'contest'
 require 'sinatra/test'
 
-require 'haml'
-require 'sass'
-require 'builder'
-
 class Sinatra::Base
   # Allow assertions in request context
   include Test::Unit::Assertions

test/sass_test.rb

@@ -1,4 +1,5 @@
 require File.dirname(__FILE__) + '/helper'
+require 'sass'
 
 class SassTest < Test::Unit::TestCase
   def sass_app(&block)