@Nested
    @DisplayName("Invalid constructor inputs")
    class InvalidInputs {
        @Test
        @DisplayName("Null delegate causes NullPointerException during construction")
        void nullDelegate_throwsNPE() throws Exception {
            SmbFile parent = newParent();
            assertThrows(NullPointerException.class, () -> new ShareEnumIterator(parent, null, null));
        }

        @Test