}

    public void test_getFilteredEnvMap_emptyKey() {
        envMap.put("", "value");
        envMap.put("VALID_KEY", "valid_value");

        final Map<String, String> filtered = systemHelper.getFilteredEnvMap(".*");
        assertEquals(1, filtered.size());
        assertEquals("valid_value", filtered.get("VALID_KEY"));
    }

    public void test_normalizeConfigPath_edgeCases() {