@Nested
    @DisplayName("Basic Constructor and Utility Tests")
    class BasicTests {

        @Test
        @DisplayName("Textual constructor happy path and toString consistency")
        void testTextualConstructorAndToString() throws Exception {
            // Arrange
            SID sid = new SID("S-1-5-21-1-2-3-1029");

            // Act & Assert
            // toString should reconstruct exact textual form