// Act & Assert
        assertThrows(NullPointerException.class, () -> handler.openConnection(null), "Null URL should throw NPE");
        verify(mockCtx, never()).getConfig(); // no interaction expected on failure before construction
    }

    @Test
    @DisplayName("openConnection uses SingletonContext when no context provided")
    void testOpenConnection_UsesSingletonContext() throws Exception {
        // Arrange

 *
 * <p><b>Warning:</b> {@code ArrayTable} is rarely the {@link Table} implementation you want. First,
 * it requires that the complete universe of rows and columns be specified at construction time.
 * Second, it is always backed by an array large enough to hold a value for every possible
 * combination of row and column keys. (This is rarely optimal unless the table is extremely dense.)

    MemoizingSupplier(Supplier<T> delegate) {
      this.delegate = checkNotNull(delegate);
    }

    @Override
    @ParametricNullness
    // We set the field only once (during construction or deserialization).
    @SuppressWarnings("SynchronizeOnNonFinalField")
    public T get() {
      // A 2-field variant of Double Checked Locking.
      if (!initialized) {
        synchronized (lock) {

    }

    @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));
        }

        when(cfg.getMaximumBufferSize()).thenReturn(5);

        BufferCacheImpl impl = new BufferCacheImpl(cfg);

        // Verify interactions happen exactly once during construction
        verify(cfg, times(1)).getBufferCacheSize();
        verify(cfg, times(1)).getMaximumBufferSize();
        verifyNoMoreInteractions(cfg);

    }

    // Test constructor
    public void test_constructor_withValidParameters() {
        // Test normal construction
        assertNotNull(securityResourceProvider);

        // Verify fields are set correctly
        InvertibleCryptographer providedInvertible = securityResourceProvider.providePrimaryInvertibleCryptographer();

        AppConfigurationEntry[] entries = cfg.getAppConfigurationEntry("ignored");
        Map<String, ?> returned = entries[0].getOptions();

        // Assert: sanity check and verify that no mutating calls were made after construction
        assertEquals("true", returned.get("refreshKrb5Config"));
        verify(spyOpts, never()).put(any(), any());
        verify(spyOpts, never()).remove(any());
        verify(spyOpts, never()).clear();
    }

            // Then
            assertNotNull(newResponse);
            // Verify the response was created successfully with the configuration
            // The constructor doesn't actually call any methods on the config during construction
        }
    }

    @Nested
    @DisplayName("Edge case tests")
    class EdgeCaseTests {

        @Test
        @DisplayName("Should handle maximum buffer index")

   * will never throw {@link ConcurrentModificationException}, and guarantees to traverse elements
   * as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect
   * any modifications subsequent to construction.
   *
   * @return an iterator over the elements in this queue
   */
  @CanIgnoreReturnValue // pushed down from class to method
  @Override

        when(this.mechContext.getFlags()).thenReturn(0x1234);
        when(this.mechContext.initSecContext(any(byte[].class), eq(0), eq(0))).thenReturn(new byte[] { 0x01, 0x02 });

        // Act: len==0 triggers initial token construction
        byte[] out = ctx.initSecContext(null, 0, 0);

        // Assert: returns a SPNEGO token (opaque here but non-null/non-empty)
        assertNotNull(out);
        assertTrue(out.length > 0);