'make perf': Unbreak by porting over 'make test' harness changes.

In particular, tests were relying on the harness to provide a sandbox working
directory, but the perf harness wasn't providing that.

tests/test-perfs.zsh

@@ -1,6 +1,6 @@
 #!/usr/bin/env zsh
 # -------------------------------------------------------------------------------------------------
-# Copyright (c) 2010-2011 zsh-syntax-highlighting contributors
+# Copyright (c) 2010-2015 zsh-syntax-highlighting contributors
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without modification, are permitted
@@ -31,20 +31,20 @@
 
 # Check an highlighter was given as argument.
 [[ -n "$1" ]] || {
-  echo "You must provide the name of a valid highlighter as argument." >&2
-  exit 1
+  echo >&2 "Bail out! You must provide the name of a valid highlighter as argument."
+  exit 2
 }
 
 # Check the highlighter is valid.
 [[ -f ${0:h:h}/highlighters/$1/$1-highlighter.zsh ]] || {
-  echo "Could not find highlighter '$1'." >&2
-  exit 1
+  echo >&2 "Bail out! Could not find highlighter '$1'."
+  exit 2
 }
 
 # Check the highlighter has test data.
 [[ -d ${0:h:h}/highlighters/$1/test-data ]] || {
-  echo "Highlighter '$1' has no test data." >&2
-  exit 1
+  echo >&2 "Bail out! Highlighter '$1' has no test data."
+  exit 2
 }
 
 # Load the main script.
@@ -53,23 +53,49 @@
 # Activate the highlighter.
 ZSH_HIGHLIGHT_HIGHLIGHTERS=($1)
 
-# Process each test data file in test data directory.
-for data_file in ${0:h:h}/highlighters/$1/test-data/*; do
+# Runs a highlighting test
+# $1: data file
+run_test_internal() {
+  local -a highlight_zone
+  local unused_highlight='bg=red,underline' # a style unused by anything else, for tests to use
+
+  local tests_tempdir="$1"; shift
+  local srcdir="$PWD"
+  builtin cd -q -- "$tests_tempdir" || { echo >&2 "Bail out! cd failed: $?"; return 1 }
+
+  echo -n "# ${1:t:r}: "
 
   # Load the data and prepare checking it.
-  BUFFER=
-  echo -n "* ${data_file:t:r}: "
-  . $data_file
+  PREBUFFER= BUFFER= ;
+  . "$srcdir"/"$1"
 
-  # Check the data declares $BUFFER.
-  if [[ ${#BUFFER} -eq 0 ]]; then
-    echo "KO\n   - 'BUFFER' is not declared or blank."
-  else
+  # Check the data declares $PREBUFFER or $BUFFER.
+  [[ -z $PREBUFFER && -z $BUFFER ]] && { echo >&2 "Bail out! Either 'PREBUFFER' or 'BUFFER' must be declared and non-blank"; return 1; }
 
-    # Measure the time taken by _zsh_highlight.
-    TIMEFMT="%*Es"
-    time ( BUFFER="$BUFFER" && _zsh_highlight)
+  # Measure the time taken by _zsh_highlight.
+  TIMEFMT="%*Es"
+  time (BUFFER="$BUFFER" && _zsh_highlight)
+}
 
-  fi
+run_test() {
+  # Do not combine the declaration and initialization: «local x="$(false)"» does not set $?.
+  local __tests_tempdir
+  __tests_tempdir="$(mktemp -d)" && [[ -d $__tests_tempdir ]] || {
+    echo >&2 "Bail out! mktemp failed"; return 1
+  }
+  typeset -r __tests_tempdir # don't allow tests to override the variable that we will 'rm -rf' later on
 
+  {
+    (run_test_internal "$__tests_tempdir" "$@")
+  } always {
+    rm -rf -- "$__tests_tempdir"
+  }
+}
+
+# Process each test data file in test data directory.
+for data_file in ${0:h:h}/highlighters/$1/test-data/*.zsh; do
+  run_test "$data_file"
+  (( $pipestatus[1] )) && exit 2
 done
+
+exit 0