code: @Test public void testQRCodeWriter() throws WriterException {
    int bigEnough=256;
    QRCodeWriter writer=new QRCodeWriter();
    BitMatrix matrix=writer.encode("http://www.google.com/",BarcodeFormat.QR_CODE,bigEnough,bigEnough,null);
    assertNotNull(matrix);
    assertEquals(bigEnough,matrix.getWidth());
    assertEquals(bigEnough,matrix.getHeight());
    int tooSmall=20;
    matrix=writer.encode("http://www.google.com/",BarcodeFormat.QR_CODE,tooSmall,tooSmall,null);
    assertNotNull(matrix);
    assertTrue(tooSmall < matrix.getWidth());
    assertTrue(tooSmall < matrix.getHeight());
    int strangeWidth=500;
    int strangeHeight=100;
    matrix=writer.encode("http://www.google.com/",BarcodeFormat.QR_CODE,strangeWidth,strangeHeight,null);
    assertNotNull(matrix);
    assertEquals(strangeWidth,matrix.getWidth());
    assertEquals(strangeHeight,matrix.getHeight());
  }
  