checkNotNull(from);
    checkNotNull(to);
    char[] buf = new char[DEFAULT_BUF_SIZE];
    int nRead;
    long total = 0;
    while ((nRead = from.read(buf)) != -1) {
      to.append(buf, 0, nRead);
      total += nRead;
    }
    return total;
  }

  /**
   * Copies all characters between the {@link Reader} and {@link Writer} objects. Does not close or

}

func (r *checksumReader) Read(b []byte) (n int, err error) {
	if r.err != nil {
		return 0, r.err
	}
	n, err = r.rc.Read(b)
	r.hash.Write(b[:n])
	r.nread += uint64(n)
	if r.nread > r.f.UncompressedSize64 {
		return 0, ErrFormat
	}
	if err == nil {
		return
	}
	if err == io.EOF {
		if r.nread != r.f.UncompressedSize64 {
			return 0, io.ErrUnexpectedEOF
		}

		t.Errorf("Read error: got %T, want testError1", err)
	}
	if _, err := rb.TryRead([]byte{0}); err != (testError1{}) {
		t.Errorf("Read error: got %T, want testError1", err)
	}
	rb.CloseWithError(testError2{})
	if _, err := rb.Read(nil); err != (testError1{}) {
		t.Errorf("Read error: got %T, want testError1", err)
	}
	if _, err := rb.Read([]byte{0}); err != (testError1{}) {

     *
     * @param b the byte array to read data into
     * @return the number of bytes read, or -1 if end of file is reached
     * @throws SmbException if an I/O error occurs
     */
    public int read(final byte b[]) throws SmbException {
        return read(b, 0, b.length);
    }

    /**
     * Reads up to len bytes from the file into the specified byte array.
     *

      }
    }

    override fun read(
      sink: Buffer,
      byteCount: Long,
    ): Long {
      require(byteCount >= 0L) { "byteCount < 0: $byteCount" }
      check(!closed) { "closed" }
      if (bytesRemaining == 0L) return -1

      val read = super.read(sink, minOf(bytesRemaining, byteCount))
      if (read == -1L) {

        // Read first message
        assertEquals(1, sis.read());
        assertEquals(2, sis.read());

        // Read second message
        assertEquals(3, sis.read());
        assertEquals(4, sis.read());
        assertEquals(5, sis.read());

        // After all data is consumed, next read throws IOException
        assertThrows(IOException.class, () -> sis.read());
    }

    @Test

    // The stream reports no bytes... importantly, it doesn't read the byte at index 5 when it
    // should be reading the byte at index 10.
    // We could use a custom InputStream instead to make the read start at index 10, but since this
    // is a racy situation anyway, this behavior seems reasonable.
    assertEquals(-1, in.read());
  }

  private static class AppendableByteSource extends ByteSource {

    assertEquals(2, lin.available());
    int read = lin.read();
    assertEquals(big[0], read);
    assertEquals(1, lin.available());
    read = lin.read();
    assertEquals(big[1], read);
    assertEquals(0, lin.available());
    read = lin.read();
    assertEquals(-1, read);

    lin.reset();
    byte[] small = new byte[5];
    read = lin.read(small);
    assertEquals(2, read);
    assertEquals(big[0], small[0]);

    }

    @Test
    @DisplayName("readn should handle multiple read calls")
    void testReadnMultipleCalls() throws IOException {
        when(mockInputStream.read(any(byte[].class), anyInt(), anyInt())).thenReturn(2) // First read returns 2 bytes
                .thenReturn(2) // Second read returns 2 bytes
                .thenReturn(1); // Third read returns 1 byte

        byte[] buffer = new byte[10];

		Method: Deflate,
		Mode:   0755 | fs.ModeDevice | fs.ModeCharDevice,
	},
}

func TestWriter(t *testing.T) {
	largeData := make([]byte, 1<<17)
	if _, err := rand.Read(largeData); err != nil {
		t.Fatal("rand.Read failed:", err)
	}
	writeTests[1].Data = largeData
	defer func() {
		writeTests[1].Data = nil
	}()

	// write a zip file
	buf := new(bytes.Buffer)
	w := NewWriter(buf)