Fix redirect/halt in before filters [#85]

lib/sinatra/base.rb

@@ -328,7 +328,7 @@ module Sinatra
 
   private
     def dispatch!
-      self.class.filters.each {|block| instance_eval(&block)}
+      self.class.filters.each { |block| invoke(block) }
       if routes = self.class.routes[@request.request_method]
         path = @request.path_info
         original_params = nested_params(@request.params)
@@ -382,6 +382,8 @@ module Sinatra
 
     def invoke(block)
       res = catch(:halt) { instance_eval(&block) }
+      return if res.nil?
+
       case
       when res.respond_to?(:to_str)
         @response.body = [res]
@@ -405,8 +407,6 @@ module Sinatra
         @response.body = res
       when (100...599) === res
         @response.status = res
-      when res.nil?
-        @response.body = []
       end
       res
     end
@@ -522,7 +522,7 @@ module Sinatra
       end
 
       def before(&block)
-        @filters << block
+        @filters << lambda { instance_eval(&block) ; nil }
       end
 
       def condition(&block)

test/filter_test.rb

@@ -32,4 +32,29 @@ describe "Filters" do
     assert ok?
     assert_equal 'bar', body
   end
+
+  it "allows redirects in filters" do
+    mock_app {
+      before { redirect '/bar' }
+      get('/foo') { 'ORLY?!' }
+    }
+
+    get '/foo'
+    assert redirect?
+    assert_equal '/bar', response['Location']
+  end
+
+  it "does not modify the response with its return value" do
+    mock_app {
+      before { 'Hello World!' }
+      get '/foo' do
+        assert_equal [], response.body
+        'cool'
+      end
+    }
+
+    get '/foo'
+    assert ok?
+    assert_equal 'cool', body
+  end
 end