Clean up button test on iOS

Author: bootstraponline

ios_tests/lib/ios/specs/ios/element/button.rb

@@ -29,8 +29,9 @@ def gray
 
   t 'buttons' do
     exp = ['Back', 'Back', 'Gray', 'Right pointing arrow']
-    buttons('a').map { |e| e.name }.must_equal exp
-    buttons('a').length.must_equal exp.length
+    target_buttons = buttons('a')
+    target_buttons.map { |e| e.name }.must_equal exp
+    target_buttons.length.must_equal exp.length
   end
 
   t 'first_button' do
@@ -52,4 +53,4 @@ def gray
   t 'after_last' do
     after_last
   end
-end
+end