public void ShouldApplyOperatorSuccefully()
{
CalculatorContainer container = new CalculatorContainer();
CalculatorExecutor executor = new CalculatorExecutor();
container.PushItem(5);
container.PushItem(7);
container.PushItem(8);
executor.ApplyOperator(container, "+");
Assert.AreEqual("5;15", container.PrettyDisplay());
container.PushItem(10);
executor.ApplyOperator(container, "-");
Assert.AreEqual("5;-5", container.PrettyDisplay());
executor.ApplyOperator(container, "*");
Assert.AreEqual("-25", container.PrettyDisplay());
}
public void ShouldApplyOperatorRaiseExceptionWhenOperatorInvalid()
{
CalculatorContainer container = new CalculatorContainer();
CalculatorExecutor executor = new CalculatorExecutor();
container.PushItem(5);
container.PushItem(5);
container.PushItem(5);
InvalidOperationException ex = Assert.Throws <InvalidOperationException>(() => executor.ApplyOperator(container, ":"));
Assert.That(ex.Message, Is.EqualTo("The symbol ':' is not recognised as a valid operator. Accepted operators are: (+, -, *, /)"));
}
public void ShouldApplyOperatorRaiseExceptionWhenStackEmpty()
{
CalculatorContainer container = new CalculatorContainer();
CalculatorExecutor executor = new CalculatorExecutor();
container.PushItem(5);
InvalidOperationException ex = Assert.Throws <InvalidOperationException>(() => executor.ApplyOperator(container, "+"));
Assert.That(ex.Message, Is.EqualTo("The stack must have at least two items to apply an operator"));
}
