@Test
 public void multShouldWorkCorrect() {
   ComplexMatrix2x2 matrix = (ComplexMatrix2x2) context.getBean("zeroMatrix");
   ComplexNumber cN = ComplexMatrix2x2Util.getComplexNumber(0, 0);
   when(cN.add(any(ComplexNumber.class))).thenReturn(cN);
   when(cN.mult(any(ComplexNumber.class))).thenReturn(cN);
   ComplexNumber[][] complexNumbers = new ComplexNumber[][] {{cN, cN}, {cN, cN}};
   assertTrue(Arrays.deepEquals(matrix.mult(matrix).getMatrix(), complexNumbers));
 }