make #provides respect Content-Type. fixes #408.

CHANGES

@@ -5,6 +5,9 @@
 
  * Add :status option support to send_file. (Konstantin Haase)
 
+ * The `provides` condition now respects an earlier set content type.
+   (Konstantin Haase)
+
  * Exception#code is only used when :use_code is enabled and displays a warning.
    Moreover, it will be ignored if the value is not between 400 and 599. You
    should use Exception#http_status instead. (Konstantin Haase)

lib/sinatra/base.rb

@@ -1163,7 +1163,9 @@ module Sinatra
         types.map! { |t| mime_types(t) }
         types.flatten!
         condition do
-          if type = request.preferred_type(types)
+          if type = response['Content-Type']
+            types.include? type or types.include? type[/^[^;]+/]
+          elsif type = request.preferred_type(types)
             content_type(type)
             true
           else

test/filter_test.rb

@@ -425,4 +425,15 @@ class AfterFilterTest < Test::Unit::TestCase
     get '/foo', {}, { 'HTTP_USER_AGENT' => 'foo' }
     assert ran
   end
+
+  it 'only triggeres provides condition if conforms with current Content-Type' do
+    mock_app do
+      before(:provides => :txt)  { @type = 'txt' }
+      before(:provides => :html) { @type = 'html' }
+      get('/') { @type }
+    end
+
+    get '/', {}, { 'HTTP_ACCEPT' => '*' }
+    assert_body 'txt'
+  end
 end

test/routing_test.rb

@@ -718,6 +718,31 @@ class RoutingTest < Test::Unit::TestCase
     assert !ok?
   end
 
+  it "filters by current Content-Type" do
+    mock_app do
+      before('/txt') { content_type :txt }
+      get('*', :provides => :txt) { 'txt' }
+
+      before('/html') { content_type :html }
+      get('*', :provides => :html) { 'html' }
+    end
+
+    get '/', {}, { 'HTTP_ACCEPT' => '*' }
+    assert ok?
+    assert_equal 'text/plain;charset=utf-8', response.headers['Content-Type']
+    assert_body 'txt'
+
+    get '/txt', {}, { 'HTTP_ACCEPT' => 'text/plain' }
+    assert ok?
+    assert_equal 'text/plain;charset=utf-8', response.headers['Content-Type']
+    assert_body 'txt'
+
+    get '/', {}, { 'HTTP_ACCEPT' => 'text/html' }
+    assert ok?
+    assert_equal 'text/html;charset=utf-8', response.headers['Content-Type']
+    assert_body 'html'
+  end
+
   it "allows multiple mime types for accept header" do
     types = ['image/jpeg', 'image/pjpeg']