@Test
public void testNumber() {

    assertEquals(9999, new FourDigitNumber(mockSlot, 9, 9, 9, 9).getNumber());
    assertEquals(999, new FourDigitNumber(mockSlot, 0, 9, 9, 9).getNumber());
    assertEquals(99, new FourDigitNumber(mockSlot, 0, 0, 9, 9).getNumber());
    assertEquals(9, new FourDigitNumber(mockSlot, 0, 0, 0, 9).getNumber());
    assertEquals(1111, new FourDigitNumber(mockSlot, 1, 1, 1, 1).getNumber());
    assertEquals(111, new FourDigitNumber(mockSlot, 0, 1, 1, 1).getNumber());
    assertEquals(11, new FourDigitNumber(mockSlot, 0, 0, 1, 1).getNumber());
    assertEquals(1, new FourDigitNumber(mockSlot, 0, 0, 0, 1).getNumber());
    assertEquals(0, new FourDigitNumber(mockSlot, 0, 0, 0, 0).getNumber());
}