@DisplayName("Edge: calling renew() on a null reference throws NPE")
    void renewOnNullReferenceThrowsNPE() {
        // Arrange: null reference to the interface
        SmbRenewableCredentials creds = null;

        // Act + Assert: invoking renew() on null triggers NullPointerException
        assertThrows(NullPointerException.class, () -> {
            // Intentional NPE through dereference of a null interface reference

    /** Constructor for use by subclasses. */
    public StandardKeySet() {
      super(ForwardingSortedMap.this);
    }
  }

  // unsafe, but worst case is a CCE or NPE is thrown, which callers will be expecting
  @SuppressWarnings({"unchecked", "nullness"})
  static int unsafeCompare(
      @Nullable Comparator<?> comparator, @Nullable Object o1, @Nullable Object o2) {

        // This method directly calls a superclass method (readResourceRecordWireFormat).
        // We need to setup fields to avoid NPE when parsing

        // Set recordName for parsing
        Field recordNameField = NameServicePacket.class.getDeclaredField("recordName");
        recordNameField.setAccessible(true);

        verify(mockDir, times(3)).getPath();
        verifyNoMoreInteractions(mockDir);
    }

    /**
     * Defensive behavior: implementation throws NPE on null inputs by design.
     */
    @Test
    @DisplayName("implementation explicitly rejects nulls with NPE")
    void implementationRejectsNulls() {
        SmbFilenameFilter filter = (dir, name) -> {
            if (dir == null || name == null) {

        // Arrange
        Handler handler = newHandlerWith(mockCtx);

        // 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")

        }));
    }

    @ParameterizedTest(name = "Invalid usage causes NPE: {0}")
    @MethodSource("npePublicGetters")
    void getters_withoutTree_throwNPE(String name, org.junit.jupiter.api.function.Executable call) {
        // Each call is invalid without a held tree and should throw NPE
        assertThrows(NullPointerException.class, call);
    }

     * {@link NullPointerException}. This test is defensive; in real code it
     * would likely be handled elsewhere.
     */
    @Test
    @DisplayName("calling getters on null reference throws NPE")
    void testNullReference() {
        AllocInfo nullRef = null;
        assertThrows(NullPointerException.class, () -> nullRef.getCapacity());
        assertThrows(NullPointerException.class, () -> nullRef.getFree());
    }

            assertEquals("smb1://", new SmbFile("smb1://server/").getParent());
            // Test parent of root - currently throws NPE due to bug in SmbFile.getParent()
            // when authority is null. This is a known issue in the legacy implementation.
            // For now, we expect the NPE to maintain backward compatibility
            assertThrows(NullPointerException.class, () -> new SmbFile("smb1://").getParent());
        }

        assertThrows(NoSuchMethodException.class, () -> SessionSetupHandler.class.getDeclaredConstructor());
    }

    @Test
    @DisplayName("Invalid: resolving class by null name throws NPE")
    void testClassForNameWithNull() {
        // Intent: demonstrate defensive behavior with null when resolving this type by name
        assertThrows(NullPointerException.class, () -> Class.forName(null));
    }

    }

    @Test
    @DisplayName("initSecContext with null buffer and non-zero len throws NPE")
    void testInitSecContextNullBufferNonZeroLen() throws Exception {
        SpnegoContext ctx = newContext();
        // A null buffer with non-zero len leads to NPE while slicing input
        assertThrows(NullPointerException.class, () -> ctx.initSecContext(null, 0, 1));