diff --git a/tests/README.md b/tests/README.md
index d55945f..b7e3450 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -39,6 +39,25 @@ which is automatically cleaned up after the test exits. For example:
       "1 21 command" # bar/testing-issue-228
     )
 
+
+Writing new tests
+-----------------
+
+An experimental tool is available to generate test files:
+
+    zsh -f tests/generate.zsh 'ls -x' \
+      | sed s/YYYY/$(date +%Y)/ \
+      > highlighters/main/test-data/foo.zsh
+    git add -N $_
+
+This generates a test file based on the current highlighting of the given `$BUFFER`
+(in this case, `ls -x`).
+
+_This tool is experimental._  Its interface may change.  In particular it may
+grow ways to set `$PREBUFFER` and/or `$ZSH_HIGHLIGHT_HIGHLIGHTERS` or to
+inject free-form code into the generated file.
+
+
 Highlighting test
 -----------------
 
diff --git a/tests/generate.zsh b/tests/generate.zsh
new file mode 100755
index 0000000..3fc0ebc
--- /dev/null
+++ b/tests/generate.zsh
@@ -0,0 +1,83 @@
+#!/usr/bin/env zsh
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2016 zsh-syntax-highlighting contributors
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without modification, are permitted
+# provided that the following conditions are met:
+#
+#  * Redistributions of source code must retain the above copyright notice, this list of conditions
+#    and the following disclaimer.
+#  * Redistributions in binary form must reproduce the above copyright notice, this list of
+#    conditions and the following disclaimer in the documentation and/or other materials provided
+#    with the distribution.
+#  * Neither the name of the zsh-syntax-highlighting contributors nor the names of its contributors
+#    may be used to endorse or promote products derived from this software without specific prior
+#    written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+# FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
+# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# -------------------------------------------------------------------------------------------------
+# -*- mode: zsh; sh-indentation: 2; indent-tabs-mode: nil; sh-basic-offset: 2; -*-
+# vim: ft=zsh sw=2 ts=2 et
+# -------------------------------------------------------------------------------------------------
+
+emulate -LR zsh
+
+# Argument parsing.
+if (( $# != 1 )) || [[ $1 == -* ]]; then
+  print -r -- >&2 "$0: usage: $0 BUFFER"
+  print -r -- >&2 ""
+  print -r -- >&2 "This tool generates a test file, suitable for highlighters/*/test-data/."
+  exit 1
+fi
+buffer=$1
+
+# Load the main script.
+. ${0:A:h:h}/zsh-syntax-highlighting.zsh
+
+# Overwrite _zsh_highlight_add_highlight so we get the key itself instead of the style
+_zsh_highlight_add_highlight()
+{
+  region_highlight+=("$1 $2 $3")
+}
+
+# Copyright block
+<$0 sed -n -e '1,/^$/p' | sed -e 's/2[0-9][0-9][0-9]/YYYY/'
+echo ""
+
+# Buffer
+print -n 'BUFFER='
+print -r -- ${(qq)buffer}
+echo ""
+
+# Expectations
+print 'expected_region_highlight=('
+() {
+  local i
+  local PREBUFFER
+  local BUFFER
+  
+  PREBUFFER=""
+  BUFFER="$buffer"
+  region_highlight=()
+  _zsh_highlight
+
+  for ((i=1; i<=${#region_highlight}; i++)); do
+    local -a highlight_zone; highlight_zone=( ${(z)region_highlight[$i]} )
+    integer start=$highlight_zone[1] end=$highlight_zone[2]
+    if (( start < end )) # region_highlight ranges are half-open
+    then
+      (( --end )) # convert to closed range, like expected_region_highlight
+      (( ++start, ++end )) # region_highlight is 0-indexed; expected_region_highlight is 1-indexed
+    fi
+    printf "  %s # %s\n" ${(qq):-"$start $end $highlight_zone[3]"} $BUFFER[start,end]
+  done
+}
+print ')'