eaa4335c34
Since the _zsh_highlight_add_highlight that the tests use ignores ZSH_HIGHLIGHT_STYLES, we can test both an injective mapping and an empty mapping at once.
zsh-syntax-highlighting / highlighters
Navigate into the individual highlighters' documentation to see
what styles ($ZSH_HIGHLIGHT_STYLES
keys) each highlighter defines.
Refer to the documentation on highlighters for further information.