Only set default charset for specific mime type. Fixes #111.

lib/sinatra/base.rb

@@ -130,8 +130,12 @@ module Sinatra
     def content_type(type, params={})
       mime_type = mime_type(type)
       fail "Unknown media type: %p" % type if mime_type.nil?
-      params[:charset] ||= params.delete('charset') || settings.default_encoding
-      response['Content-Type'] = "#{mime_type};#{params.map { |kv| kv.join('=') }.join(', ')}"
+      mime_type = mime_type.dup
+      unless params.include? :charset or settings.add_charset.all? { |p| not p === mime_type }
+        params[:charset] = params.delete('charset') || settings.default_encoding
+      end
+      mime_type << ";#{params.map { |kv| kv.join('=') }.join(', ')}" unless params.empty?
+      response['Content-Type'] = mime_type
     end
 
     # Set the Content-Disposition to "attachment" with the specified filename,
@@ -1238,6 +1242,7 @@ module Sinatra
     set :logging, false
     set :method_override, false
     set :default_encoding, "utf-8"
+    set :add_charset, [/^text\//, 'application/javascript', 'application/xml', 'application/xhtml+xml']
 
     class << self
       alias_method :methodoverride?, :method_override?

test/helpers_test.rb

@@ -320,7 +320,7 @@ class HelpersTest < Test::Unit::TestCase
 
       get '/foo.xml'
       assert ok?
-      assert_equal 'application/foo;charset=utf-8', response['Content-Type']
+      assert_equal 'application/foo', response['Content-Type']
       assert_equal 'I AM FOO', body
     end
 
@@ -334,6 +334,32 @@ class HelpersTest < Test::Unit::TestCase
 
       assert_raise(RuntimeError) { get '/foo.xml' }
     end
+
+    it 'only sets default charset for specific mime types' do
+      tests_ran = false
+      mock_app do
+        mime_type :foo, 'text/foo'
+        mime_type :bar, 'application/bar'
+        mime_type :baz, 'application/baz'
+        add_charset << mime_type(:baz)
+        get '/' do
+          assert_equal content_type(:txt),    'text/plain;charset=utf-8'
+          assert_equal content_type(:css),    'text/css;charset=utf-8'
+          assert_equal content_type(:html),   'text/html;charset=utf-8'
+          assert_equal content_type(:foo),    'text/foo;charset=utf-8'
+          assert_equal content_type(:xml),    'application/xml;charset=utf-8'
+          assert_equal content_type(:xhtml),  'application/xhtml+xml;charset=utf-8'
+          assert_equal content_type(:js),     'application/javascript;charset=utf-8'
+          assert_equal content_type(:bar),    'application/bar'
+          assert_equal content_type(:png),    'image/png'
+          assert_equal content_type(:baz),    'application/baz;charset=utf-8'
+          tests_ran = true
+          "done"
+        end
+      end
+      get '/'
+      assert tests_ran
+    end
   end
 
   describe 'send_file' do
@@ -378,7 +404,7 @@ class HelpersTest < Test::Unit::TestCase
     it 'sets the Content-Type response header if type option is set to a mime type' do
       send_file_app :type => 'application/octet-stream'
       get '/file.txt'
-      assert_equal 'application/octet-stream;charset=utf-8', response['Content-Type']
+      assert_equal 'application/octet-stream', response['Content-Type']
     end
 
     it 'sets the Content-Length response header' do