fix escaping Unicode characters in Ruby 1.8.7

In Ruby 1.8, when you are operating with unicode encoding, \w includes
UTF-8 characters such as ☃. Faraday therefore does not escape these
correctly.

Closes #245

lib/faraday/parameters.rb

@@ -1,6 +1,6 @@
 module Faraday
   module NestedParamsEncoder
-    ESCAPE_RE = /[^\w .~-]+/
+    ESCAPE_RE = /[^a-zA-Z0-9 .~_-]/
 
     def self.escape(s)
       return s.to_s.gsub(ESCAPE_RE) {
@@ -117,7 +117,7 @@ def self.decode(query)
   end
 
   module FlatParamsEncoder
-    ESCAPE_RE = /[^\w .~-]+/
+    ESCAPE_RE = /[^a-zA-Z0-9 .~_-]/
 
     def self.escape(s)
       return s.to_s.gsub(ESCAPE_RE) {

lib/faraday/utils.rb

@@ -155,7 +155,7 @@ def build_nested_query(params)
       NestedParamsEncoder.encode(params)
     end
 
-    ESCAPE_RE = /[^\w .~-]+/
+    ESCAPE_RE = /[^a-zA-Z0-9 .~_-]/
 
     def escape(s)
       s.to_s.gsub(ESCAPE_RE) {

test/request_middleware_test.rb

@@ -17,6 +17,20 @@ def setup
     end
   end
 
+  def with_utf8
+    if defined?(RUBY_VERSION) && RUBY_VERSION.match(/1.8.\d/)
+      begin
+        previous_kcode = $KCODE
+        $KCODE = "UTF8"
+        yield
+      ensure
+        $KCODE = previous_kcode
+      end
+    else
+      yield
+    end
+  end
+
   def test_does_nothing_without_payload
     response = @conn.post('/echo')
     assert_nil response.headers['Content-Type']
@@ -66,6 +80,16 @@ def test_url_encoded_unicode
     assert err.empty?
   end
 
+  def test_url_encoded_unicode_with_kcode_set
+    with_utf8 do
+      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
+  end
+
   def test_url_encoded_nested_keys
     response = @conn.post('/echo', {'a'=>{'b'=>{'c'=>['d']}}})
     assert_equal "a%5Bb%5D%5Bc%5D%5B%5D=d", response.body