Add comparison script

tests/syntax-tests/regression_test.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+set -eou pipefail
+
+script_directory="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+
+output_directory=$(mktemp -d --suffix=.bat-syntax-regression-test)
+
+"$script_directory"/create_highlighted_versions.py --output="$output_directory"
+
+echo
+
+"$script_directory"/compare_highlighted_versions.py \
+    "$script_directory/highlighted" \
+    "$output_directory"