t0001: replace "test [-d|-f]" with test_path_is_* functions

Signed-off-by: Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0001-init.sh

@@ -6,7 +6,8 @@ TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 check_config () {
-	if test -d "$1" && test -f "$1/config" && test -d "$1/refs"
+	if test_path_is_dir "$1" &&
+	   test_path_is_file "$1/config" && test_path_is_dir "$1/refs"
 	then
 		: happy
 	else