“Draft” mode for document

Suppose you want to keep two versions of the same document: one where you highlight changes and one where you show the final result. How can I use a "debug" or "test" mode to turn on/off my \textbf commands? Example:

\documentclass[phd,testing]{nuthesis}
\begin{document}
This is old.
\if testing, \textbf{This is new.}
\end{document}


I would like the following when in testing:

This is old.
This is new.

And this when not in testing:

This is old.
This is new.

• \newif\iftesting and then \newcommand{\testing}[1]{\iftesting \textbf{#1}\else #1\fi}. Then you can turn it "on" with \testingtrue (the default is \testingfalse). It can be done mid-document. – jon Oct 14 '15 at 2:40
• Please read this useful information: Welcome to TeX.SX! and I've just been asked to write a minimal example, what is that?, to learn about and improve your way for writing questions on this site. – OSjerick Oct 14 '15 at 2:49
• You might also use \DeclareOption{testing}{\testingtrue} – John Kormylo Oct 14 '15 at 3:56
• ctan.org/topic/cond-comp – Fran Oct 14 '15 at 7:37