[XeTeX] fontspec error (maybe?), but only in class file

[Patrick Carr]

Pertaining to these two minimal files:

-----

Minimal testing.cls file:

\ProvidesClass{testing}
\RequirePackage{fontspec}
\LoadClass{article}

-----

Minimal tex file:

\documentclass{testing}
%\usepackage{fontspec}
\begin{document}
This is a test.\\
\end{document}

-----

When run as above, I get this error:

This is XeTeX, Version 3.14159265-2.6-0.99992 (TeX Live 2015)
(preloaded format=xelatex)
 restricted \write18 enabled.
entering extended mode
(./Sans-titre.tex
LaTeX2e <2016/03/31>
Babel <3.9q> and hyphenation patterns for 81 language(s) loaded.
(/Users/pat/Library/texmf/tex/latex/testing.cls
Document Class: testing
(/usr/local/texlive/2015/texmf-dist/tex/latex/fontspec/fontspec.sty
(/usr/local/texlive/2015/texmf-dist/tex/latex/l3kernel/expl3.sty
(/usr/local/texlive/2015/texmf-dist/tex/latex/l3kernel/expl3-code.tex)
(/usr/local/texlive/2015/texmf-dist/tex/latex/l3kernel/l3xdvipdfmx.def))
(/usr/local/texlive/2015/texmf-dist/tex/latex/l3packages/xparse/xparse.sty)
(/usr/local/texlive/2015/texmf-dist/tex/latex/fontspec/fontspec-xetex.sty
(/usr/local/texlive/2015/texmf-dist/tex/latex/base/fontenc.sty
(/usr/local/texlive/2015/texmf-dist/tex/latex/euenc/eu1enc.def)
(/usr/local/texlive/2015/texmf-dist/tex/latex/euenc/eu1lmr.fd))

! LaTeX Error: The font size command \normalsize is not defined:
               there is probably something wrong with the class file.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.293 \normalsize
                  % to overcome the encoding changing the current font size
?

-----

When run with the call to fontspec in the class file commented out and
uncommented in the tex file, it runs fine. That's line 293 from
fontspec-xetex.sty; in the method that runs correctly it loads
xunicode and moves on.

The fontspec files are dated 1 february 2016, which I think is
current. I'm editing the tex files in TeXShop and the class files in
emacs, if it's some source file encoding issue, but I'm doing it the
same for both. Xunicode is of course from 2011.

Did I just miss or screw up an update or something? I tried searching
on the errors and the best I could describe it here, on stack
exchange, and the googles, but maybe I was searching for the wrong
thing?

Thanks,

Pat Carr