zsh older than workers/28418 (zsh revision 23bdfc7fd2)
doesn't support the «${name:offset:length}» syntax.  Therefore, use the older
«$name[start,end]» syntax instead.

Followup to 3cb58fd7d7b9e42067ffcf24892114dc2c9b26e4, "Optimization: -1 is
extra computation of string length internally".

Fixes zsh-users/zsh-syntax-highlighting#279.

While here, also add a test for the '!' reserved word (which is highlighted
since c216242b).

This is a continuation of 451665cb2a which did
the same for the $PS3 prompt.

Reported-by: Sebastian Gniazdowski

./parse.zsh "zplugin.zsh" > out_norm.txt 106,17s user 7,84s system 98% cpu 1:55,85 total

./parse.zsh "zplugin.zsh" > out_opt.txt 51,91s user 7,44s system 99% cpu 59,912 total

% wc -l zplugin.zsh
3188 zplugin.zsh

The input to the $PS3 prompt is not commands, so the 'main' highlighter is
not applicable to it.

Fixes zsh-users/zsh-syntax-highlighting#268.

This fixes fd's specified by a (single) digit.  The named fd syntax remains an XFail.

The default for [redirection] is 'none', so it wasn't actually being tested.

The important part of this change is removing the second conjunct from the
condition; the remainder of the change gives one example of when that matters.

At this time, no user-visible consequences are known.

Done in c30301d474 and
c687bddea3 for other tests.

Fixes zsh-users/zsh-syntax-highlighting#101.

This builds upon the test harness auto-cleaned-up directories work (c01533920).

There's simply no reason to use such names, now that the filename is no longer
itself test data.

Fixes zsh-users/zsh-syntax-highlighting#182.
Prerequisite for testing issue #228.

* tests/test-highlighting.zsh
  (run_test): Move functionality to run_test_internal; make run_test be a wrapper
    that handles creating and cleaning up the tempdir.

* tests/README.md: Document the new feature.

* "highlighters/main/test-data/path-space- .zsh"
* highlighters/main/test-data/path-tilde-named.zsh
* highlighters/main/test-data/path.zsh
    Change test data to not depend on being run from the source directory.

Followup to c0dafd1d850e582291b41d693369794d1ea31343, which changed the highlight of
those ')'s from <nothing> to [reserved-word].

Followup to 0d1bfbcbfa.

Reported-by: Antony Lee

The following warnings are issued by zsh as of zsh-workers/37018 (commit
de9effbce601 to zsh itself):

_zsh_highlight_main_highlighter_highlight_dollar_string:17: array parameter match created globally in function _zsh_highlight_main_highlighter_highlight_dollar_string
_zsh_highlight_main_highlighter_highlight_dollar_string:17: array parameter mbegin created globally in function _zsh_highlight_main_highlighter_highlight_dollar_string
_zsh_highlight_main_highlighter_highlight_dollar_string:17: array parameter mend created globally in function _zsh_highlight_main_highlighter_highlight_dollar_string
_zsh_highlight_main_highlighter_highlight_dollar_string:17: numeric parameter parameter MBEGIN created globally in function _zsh_highlight_main_highlighter_highlight_dollar_string
_zsh_highlight_main_highlighter_highlight_dollar_string:17: numeric parameter parameter MEND created globally in function _zsh_highlight_main_highlighter_highlight_dollar_string
_zsh_highlight_main_highlighter_highlight_dollar_string:17: scalar parameter MATCH created globally in function _zsh_highlight_main_highlighter_highlight_dollar_string
_zsh_highlight_main_highlighter_highlight_string:11: array parameter match created globally in function _zsh_highlight_main_highlighter_highlight_string
_zsh_highlight_main_highlighter_highlight_string:11: array parameter mbegin created globally in function _zsh_highlight_main_highlighter_highlight_string
_zsh_highlight_main_highlighter_highlight_string:11: array parameter mend created globally in function _zsh_highlight_main_highlighter_highlight_string
_zsh_highlight_main_highlighter_highlight_string:11: numeric parameter parameter MBEGIN created globally in function _zsh_highlight_main_highlighter_highlight_string
_zsh_highlight_main_highlighter_highlight_string:11: numeric parameter parameter MEND created globally in function _zsh_highlight_main_highlighter_highlight_string
_zsh_highlight_main_highlighter_highlight_string:11: scalar parameter MATCH created globally in function _zsh_highlight_main_highlighter_highlight_string

zsh prior to workers/32609 (commit 9d47e8398d)
does not support the (-n)-less «[[ $var ]]» syntax.

Fixes zsh-users/zsh-syntax-highlighting#225.

This is already done for commands prematurely terminated by ";".