test failure would not be reflected by the exit code of 'make'.
Setting a shell parameter in the left-hand side of a pipe is not visible to
commands after the pipe, because the left-hand side forks. (That's true both
in 'sh' used by 'make' and in 'zsh' that runs tests/test-highlighting.zsh, at
least on my system.) Therefore, move the colorizing hook to where it doesn't
interfere with setting the $something_failed (in tests/test-highlighting.zsh)
and $result (in Makefile) parameters.
All these files should be sourced, not executed; and Debian's lintian complains:
W: zsh-syntax-highlighting: script-not-executable usr/share/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh
* Don't override user defined styles
* Better modularisation of highlighters
* Allow to define which highlighters are activated
* Allow to define the order in which they are defined
* Minor performance optimizations
* Fixed some variables leak
* Improve documentation
* Brackets highlighter: use ZSH_HIGHLIGHT_STYLES instead of a specific array