Test Adapters: Always use the last output for score runs

* This prevents learners from cheating by printing the required status line themselves

lib/r_script_adapter.rb

@@ -9,11 +9,11 @@ class RScriptAdapter < TestingFrameworkAdapter
   end
 
   def parse_output(output)
-    captures = REGEXP.match(output[:stdout]).captures.map(&:to_i)
+    captures = output[:stdout].scan(REGEXP).try(:last).map(&:to_i)
     count = captures.first
     passed = captures.second
     failed = count - passed
-    assertion_error_matches = output[:stdout].scan(ASSERTION_ERROR_REGEXP).flatten || []
-    {count: count, failed: failed, error_messages: assertion_error_matches}
+    assertion_error_matches = output[:stdout].scan(ASSERTION_ERROR_REGEXP) || []
+    {count: count, failed: failed, error_messages: assertion_error_matches.flatten.reject(&:blank?)}
   end
 end