JAASAuthenticator auth = spy(new JAASAuthenticator());
        // Avoid real JAAS by stubbing getSubject
        doReturn(new Subject()).when(auth).getSubject();

        // Act
        CredentialsInternal result = auth.renew();

        // Assert interaction and return value
        assertSame(auth, result);
        verify(auth, times(1)).getSubject();
    }

        // Destination has guard space to verify non-overwritten regions.
        byte[] dst = new byte[dstIndex + len + 5];
        Arrays.fill(dst, (byte) 0x55);

        // Act
        int written = enc.encode(dst, dstIndex);

        // Assert: reported written bytes matches size() and requested len.
        assertEquals(len, enc.size(), "size() must equal provided length");

    void enumUsedWithCollaboratorHasNoSideEffects() {
        // Arrange: pick a value and a mocked consumer
        RequestParam rp = RequestParam.NO_RETRY;

        // Act: pass to the collaborator
        consumer.accept(rp);

        // Assert: interaction happened exactly once with correct argument; no other calls
        verify(consumer, times(1)).accept(RequestParam.NO_RETRY);

            }
            resp.received();
            return resp;
        });

        DirFileEntryEnumIterator1 it = new DirFileEntryEnumIterator1(tree, parent, "*", null, 0);

        // Act & Assert: entries a, b, c (dot entries filtered) then end
        assertTrue(it.hasNext());
        assertEquals("a", it.next().getName());
        assertTrue(it.hasNext());
        assertEquals("b", it.next().getName());

        when(peek.getReadDataAvailable()).thenReturn(7);
        when(ioResp.getOutputData()).thenReturn(peek);

        when(tree.send(any(Smb2IoctlRequest.class), eq(RequestParam.NO_RETRY))).thenReturn(ioResp);

        // Act
        int available = stream.available();

        // Assert
        assertEquals(7, available, "Should return available bytes reported by server");

        void testDcerpcUuidSyntaxNdr() {
            // Arrange
            String expectedUuid = "8a885d04-1ceb-11c9-9fe8-08002b104860";

            // Act
            String actualUuid = DcerpcConstants.DCERPC_UUID_SYNTAX_NDR.toString().toLowerCase();

            // Assert
            assertNotNull(DcerpcConstants.DCERPC_UUID_SYNTAX_NDR, "DCERPC_UUID_SYNTAX_NDR should not be null");

            }
        }
        return pipeIn;
    }

    /**
     * Return the <code>OutputStream</code> used to write
     * information to this pipe instance. The act of writing data
     * to this stream will result in response data recieved in the
     * <code>InputStream</code> associated with this Named Pipe

        // Arrange: first ensureTreeConnected comes from pipe
        when(pipe.ensureTreeConnected()).thenReturn(tree);
        when(tree.acquire()).thenReturn(tree); // method returns itself per implementation

        // Act: call twice
        try (SmbTreeHandleImpl t1 = target.ensureTreeConnected(); SmbTreeHandleImpl t2 = target.ensureTreeConnected()) {
            assertSame(tree, t1);
            assertSame(tree, t2);
        }

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