public void Calc_Success() { var inputStack = new Stack <decimal>(); inputStack.Push(1); inputStack.Push(2); var(result, history, resultMemberCount) = _calculator.Calculate(inputStack); result.Count.Should().Be(1); result.First().Should().Be(-1); history.Count.Should().Be(2); history.First().Should().Be(1); history.Last().Should().Be(2); resultMemberCount.Should().Be(1); }