public void It_should_add_numbers()
{
var calculator = new CalculatorInternal();
calculator.Add(2);
calculator.Add(2);
Assert.AreEqual(4, calculator.Total);
}
public void It_should_add_two_calculators_together()
{
var calculatorA = new CalculatorInternal();
calculatorA.Add(2);
var calculatorB = Substitute.For <ICalculator>();
calculatorB.Total.Returns(2);
calculatorA.Add(calculatorB);
Assert.AreEqual(4, calculatorA.Total);
}