@Test
  public void shouldCalculateSquare() {
    ComplexNumber number1 = new ComplexNumber(2, 3);
    assertEquals(-5, number1.getSquare().getReal(), 0);
    assertEquals(12, number1.getSquare().getImaginary(), 0);

    ComplexNumber number2 = new ComplexNumber(4, 2);
    assertEquals(12, number2.getSquare().getReal(), 0);
    assertEquals(16, number2.getSquare().getImaginary(), 0);
  }
 @Test
 public void shouldCalculateSquareWithNegativeRealAndImaginary() {
   ComplexNumber number = new ComplexNumber(-5, -3);
   assertEquals(16, number.getSquare().getReal(), 0);
   assertEquals(30, number.getSquare().getImaginary(), 0);
 }
 @Test
 public void shouldCalculateSquareWithNegativeImaginary() {
   ComplexNumber number = new ComplexNumber(3, -2);
   assertEquals(5, number.getSquare().getReal(), 0);
   assertEquals(-12, number.getSquare().getImaginary(), 0);
 }