test: added validation regex argument to test

In this change, I've added the regex pattern to the assert.throws()
in order to provide the validation argument for the call.

PR-URL: https://github.com/nodejs/node/pull/9918


Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>