@Test
public void shouldReturnZeroIfOperationsAreCancelled() {
Calculator calculator = new Calculator();
calculator.cancel();
assertEquals(0.0, calculator.cancel(), 0.0001);
}
@Test
public void shouldReturnTheNumberIfTheNumberIsAddedAfterOperationsAreCancelled() {
Calculator calculator = new Calculator();
calculator.add(5.0);
calculator.cancel();
assertEquals(5.0, calculator.add(5.0), 0.0001);
}
