#nil? or :undef

gistfile1.txt

@@ -14,10 +14,10 @@ server {
   ssl_protocols             <%= @ssl_protocols %>;
   ssl_ciphers               <%= @ssl_ciphers %>;
   ssl_prefer_server_ciphers on;
-<% if @auth_basic != :undef -%>
+<% unless @auth_basic.nil? -%>
   auth_basic                "<%= @auth_basic %>";
 <% end -%>
-<% if @auth_basic_user_file != :undef -%>
+<% unless @auth_basic_user_file.nil? -%>
   auth_basic_user_file      <%= @auth_basic_user_file %>;
 <% end -%>