In send_file: Do not override Content-Type if already set and no explicit type

is given.

Fixes #130.

lib/sinatra/base.rb

@@ -166,8 +166,9 @@ module Sinatra
       stat = File.stat(path)
       last_modified stat.mtime
 
-      content_type opts[:type] || File.extname(path),
-        :default => response['Content-Type'] || 'application/octet-stream'
+      if opts[:type] or not response['Content-Type']
+        content_type opts[:type] || File.extname(path), :default => 'application/octet-stream'
+      end
 
       if opts[:disposition] == 'attachment' || opts[:filename]
         attachment opts[:filename] || path

test/helpers_test.rb

@@ -454,6 +454,30 @@ class HelpersTest < Test::Unit::TestCase
       get '/file.txt'
       assert_equal 'application/octet-stream', response['Content-Type']
     end
+
+    it "does not override Content-Type if already set and no explicit type is given" do
+      path = @file
+      mock_app do
+        get '/' do
+          content_type :png
+          send_file path
+        end
+      end
+      get '/'
+      assert_equal 'image/png', response['Content-Type']
+    end
+
+    it "does override Content-Type even if already set, if explicit type is given" do
+      path = @file
+      mock_app do
+        get '/' do
+          content_type :png
+          send_file path, :type => :gif
+        end
+      end
+      get '/'
+      assert_equal 'image/gif', response['Content-Type']
+    end
   end
 
   describe 'cache_control' do