Cast to string if field has maxlength value, closes #989

lib/capybara/rack_test/node.rb

@@ -153,7 +153,7 @@ private
     if text_or_password? && attribute_is_not_blank?(:maxlength)
       # Browser behavior for maxlength="0" is inconsistent, so we stick with
       # Firefox, allowing no input
-      value = value[0...self[:maxlength].to_i]
+      value = value.to_s[0...self[:maxlength].to_i]
     end
     if Array === value #Assert multiple attribute is present
       value.each do |v|

lib/capybara/spec/session/fill_in_spec.rb

@@ -109,6 +109,12 @@ Capybara::SpecHelper.spec "#fill_in" do
     extract_results(@session)['first_name'].should == 'Harry'
   end
 
+  it "casts to string if field has maxlength", :focus => true do
+    @session.fill_in(:'form_zipcode', :with => 1234567)
+    @session.click_button('awesome')
+    extract_results(@session)['zipcode'].should == '12345'
+  end
+
   context 'on a pre-populated textfield with a reformatting onchange', :requires => [:js] do
     it 'should only trigger onchange once' do
       @session.visit('/with_js')