Add a simple test for checkSpace.pl

This script is not expected to work on windows due to line-ending
issues, so I'm not making it get run on an automated basis.  We
should use it when editing checkSpace.pl.

Closes ticket 32613.

scripts/maint/checkSpaceTest.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+# Copyright 2019, The Tor Project, Inc.
+# See LICENSE for licensing information
+
+# Integration test for checkSpace.pl, which we want to rewrite.
+
+umask 077
+set -e
+
+# make a safe space for temporary files
+DATA_DIR=$(mktemp -d -t tor_checkspace_tests.XXXXXX)
+trap 'rm -rf "$DATA_DIR"' 0
+
+RECEIVED_FNAME="${DATA_DIR}/got.txt"
+
+cd "$(dirname "$0")/checkspace_tests"
+
+# we expect this to give an error code.
+../checkSpace.pl -C ./*.[ch] ./*/*.[ch] > "${RECEIVED_FNAME}" && exit 1
+
+diff -u expected.txt "${RECEIVED_FNAME}" || exit 1
+
+echo "OK"