yield the MockRequest to the block before invoking the app [sinatra#111]

sr commented this out during some refactoring but I'd like
to leave it in for now.

lib/sinatra/test.rb

@@ -33,7 +33,7 @@ def make_request(verb, path, data=nil, h=nil)
         options[:input] = data
       end
 
-      # TODO: yield @request if block_given?
+      yield @request if block_given?
       @response = @request.request(verb, path, options)
     end
 

test/test_test.rb

@@ -101,6 +101,15 @@ def request_params
     assert_equal 'text/plain', request['CONTENT_TYPE']
   end
 
+  it 'yields the request object to the block before invoking the application' do
+    called = false
+    get '/' do |req|
+      called = true
+      assert req.kind_of?(Rack::MockRequest)
+    end
+    assert called
+  end
+
   def test_TestHarness
     session  = Sinatra::TestHarness.new(@app)
     response = session.get('/')