Constructor by type not found error in PrivateObject

Question

I am writing unit test to calculate software. In the test case, I used " PrivateObject" to access the private method " sendNumberToCalculation()", but I get an error constructor of a type that was not found.

    public class CalculationTest
{
    [TestMethod]
    public void sendNumberToCalculationTest()
    {

        // -- Act
        PrivateObject obj = new PrivateObject(typeof(Calculation));
        Tokenization token = new Tokenization("5*10-18/(3+19)");
        PolishNotation polish = new PolishNotation(token.MathExpressionParser());

        double expected = 49.19;

        // -- Actual
        double actual = Convert.ToDouble(obj.Invoke("sendNumberToCalculation", polish));

        // -- Assert
        Assert.AreEqual(expected, actual);
    }
}

    public class Calculation
{

    private Tokenization token;

    private PolishNotation polish;
    private Stack<double> numbers = new Stack<double>();
    private Stack<string> operators = new Stack<string>();

    public Calculation(string expression)
    {
        token = new Tokenization(expression);
        polish = new PolishNotation(token.MathExpressionParser());
    }

    private double sendNumberToCalculation()
    {
        int number;
        int number1 = 0;
        int number2 = 0;
        string operatorName = "";
        int counter = 1;
        foreach (var item in polish.InfixToPostfix())
        {
            numbers.Push(Convert.ToDouble(item));
            if (!int.TryParse(item, out number))
            {
                operators.Push(item);
                while (counter <= 2 && numbers.Count > 1)
                {
                    if (counter == 1)
                    {
                        number2 = Convert.ToInt32(numbers.Pop());
                    }
                    else if (counter == 2 && operators.Count > 0)
                    {
                        number1 = Convert.ToInt32(numbers.Pop());
                        operatorName = operators.Pop();
                    }
                }
            }
            operatorDetect(number1, number2, operatorName);
        }
        var result = numbers.Pop();

        return result;
    }

    private void operatorDetect(int number1, int number2, string operatorName)
    {
        switch (operatorName)
        {
            case "+":
                Add(number1, number2);
                break;

            case "*":
                Multipy(number1, number2);
                break;

            case "/":
                Divide(number1, number2);
                break;

            case "-":
                Subtract(number1, number2);
                break;
        }
    }

    private void Add(int number1, int number2)
    {
        double number = number1 + number2;
        numbers.Push(number);
    }

    private void Multipy(int number1, int number2)
    {
        double number = number1 * number2;
        numbers.Push(number);
    }

    private void Subtract(int number1, int number2)
    {
        double number = number1 / number2;
        numbers.Push(number);
    }

    private void Divide(int number1, int number2)
    {
        double number = number1 - number2;
        numbers.Push(number);
    }
}

Answer 1

The calculation class does not contain a constructor without parameters. pass constructor parameters constructor PrivateObject:

string expression = "5*10-18/(3+19)";

PrivateObject obj = new PrivateObject(
    typeof(Calculation),      // The type of the object to create
    new[] { typeof(string) }, // The type of each parameter
    new[] { expression });    // The value for each parameter

to call the sendNumberToCalculation method with one parameter of type PolishNotation, but this method has no parameters. to remove the second argument from the Invoke call:

double actual = Convert.ToDouble(obj.Invoke("sendNumberToCalculation"));

Answer 2

, , PrivateObject, .