[utest] fix libc issue
@@ -50,8 +50,8 @@ void utest_assert_buf(const char *a, const char *b, rt_size_t sz, rt_bool_t equa
*/
#define uassert_true(value) __utest_assert(value, "(" #value ") is false")
#define uassert_false(value) __utest_assert(!(value), "(" #value ") is true")
-#define uassert_null(value) __utest_assert((const char *)(value) == NULL, "(" #value ") is not null")
-#define uassert_not_null(value) __utest_assert((const char *)(value) != NULL, "(" #value ") is null")
+#define uassert_null(value) __utest_assert((const char *)(value) == RT_NULL, "(" #value ") is not null")
+#define uassert_not_null(value) __utest_assert((const char *)(value) != RT_NULL, "(" #value ") is null")
#define uassert_int_equal(a, b) __utest_assert((a) == (b), "(" #a ") not equal to (" #b ")")
#define uassert_int_not_equal(a, b) __utest_assert((a) != (b), "(" #a ") equal to (" #b ")")
