### Question:
Calculator implements ICalculator { @Override public String add(int... values) { int sum = 0; for (int value : values) { sum += value; } return format(sum); }  @Override String add(int... values); @Override String multiply(int... values); @Override String evaluate(String value);  }### Answer:
@Test public void testAdd() { assertEquals("3", mCalculator.evaluate(Matchers.anyString())); final String result = mCalculator.add(1,2); assertEquals("3", result); when(mCalculator.evaluate(Matchers.anyString())).thenReturn("5"); assertEquals("5", mCalculator.evaluate(Matchers.anyString())); }