show any diagnostics that might come out of bats tests.

also adds comment about diagnostic messages in bats.

utils/tests.sh

@@ -6,4 +6,7 @@ set -e
 
 # Running all the bats-tests in a dir with spaces:
 cd "${SECRET_PROJECT_ROOT}"; rm -rf 'tempdir with spaces'; mkdir 'tempdir with spaces'; cd 'tempdir with spaces';
-bats "${SECRET_PROJECT_ROOT}/tests"
+
+# bats expects diagnostic lines to be sent to fd 3, matching reges '^ #' (IE, like: echo "# message here")
+# 3>&1 shows diagnostic output when errors occur.
+bats --tap "${SECRET_PROJECT_ROOT}/tests/" 3>&1