Fix infinite loop with usage()

test/runtests

@@ -8,6 +8,11 @@ export LC_ALL=C
 
 export TF_PROJDIR="$PWD"
 
+usage() {
+    echo "usage: $(basename $0) [-c] [-t tests_re] [-s subtest_re] [-p binpath] [-v] [-d]" >&2
+    exit 2
+}
+
 while true; do case "$1" in
     -c|--collect)           export TF_COLLECT=always; shift ;;
     -t|--filter-test)       export TF_FILTER_TEST="$2"; shift 2 ;;
@@ -16,6 +21,7 @@ while true; do case "$1" in
     -d|--debug)             export TF_DEBUG=true; shift ;;
     -v|--verbose)           export TF_VERBOSE=true; shift ;;
     "") break ;;
+    *)  usage ;;
 esac done
 
 time tf_run_tests