ensure no regex warnings about UTF-8 strings

This is a cherry-pick of 3dddbfcd776930910d065744517394565339ec2f

References #95

test/helper.rb

@@ -1,4 +1,5 @@
 require 'test/unit'
+require 'stringio'
 
 if ENV['LEFTRIGHT']
   begin
@@ -29,6 +30,16 @@ module Faraday
     def test_default
       assert true
     end unless defined? ::MiniTest
+
+    def capture_warnings
+      old, $stderr = $stderr, StringIO.new
+      begin
+        yield
+        $stderr.string
+      ensure
+        $stderr = old
+      end
+    end
   end
 end
 

test/request_middleware_test.rb

@@ -1,3 +1,4 @@
+# encoding: utf-8
 require File.expand_path(File.join(File.dirname(__FILE__), 'helper'))
 
 Faraday::CompositeReadIO.send :attr_reader, :ios
@@ -47,6 +48,14 @@ class RequestMiddlewareTest < Faraday::TestCase
     assert_equal expected, Faraday::Utils.parse_nested_query(response.body)
   end
 
+  def test_url_encoded_unicode
+    err = capture_warnings {
+      response = @conn.post('/echo', {:str => "eé cç aã aâ"})
+      assert_equal "str=e%C3%A9+c%C3%A7+a%C3%A3+a%C3%A2", response.body
+    }
+    assert err.empty?
+  end
+
   def test_multipart
     # assume params are out of order
     regexes = [