String literals may be shared by the compiler, so the test string
needs to be copied before adding properties to it. For single
properties, just use a string literal with properties.
* test/lisp/emacs-lisp/faceup-tests/faceup-test-basics.el
(faceup-markup): Split into...
(faceup-markup-basics, faceup-markup-escaping, faceup-markup-plain)
(faceup-markup-plain-full-text, faceup-markup-anonymous-face)
(faceup-markup-anonymous-face-2keys, faceup-markup-anonymous-nested)
(faceup-markup-nested, faceup-markup-overlapping)
(faceup-markup-multi-face, faceup-markup-multi-property): New tests.
dbe410d9ad