instructions.md

While working at Instruments of Texas, you are tasked to work on an experimental calculator written in C#. You are building a test harness to verify a number of calculator functions starting with multiplication. You will see that there is particular concern when the two operands of the multiplication are negative.

The Calculator class has been provided for you and should not be modified.

1. Complete the definition of the user-defined exception CalculationException

Complete the definition of the constructor of CalculationException which will need to store (wrap) any exception thrown by the calculator as well as the operands that are being processed at the time the exception is thrown.

2. Handle overflow conditions in the calculator and provide enhanced information to the caller

Implement the CalculatorTestHarness.Multiply() method, which should call the Calculator.Multiply() method of the Calculator instance passed to the constructor. passing in x and y integer values. If an overflow occurs in the Calculator.Multiply() method, it will throw an OverflowException. This exception should be caught in the CalculatorTestHarness.Multiply() method and wrapped in a CalculationException and the x and y values being passed around should be stored as the exception's operands. The newly created CalculationException object should be thrown. You can ignore the value returned by the Calculator.Multiply() method if it is successful.

var cth = new CalculatorTestHarness(new Calculator());
cth.Multiply(Int32.MaxValue, Int32.MaxValue);
// => throws an instance of CalculationException

var cth2 = new CalculatorTestHarness(new Calculator());
cth2.Multiply(3, 2);
// => silently exits

3. Test the multiplication operation for valid inputs

Implement the CalculatorTestHarness.TestMultiplication() method which takes two integers and calls the CalculatorTestHarness.Multiply() method. "Multiply succeeded" is returned.

var cth = new CalculatorTestHarness(new Calculator());
cth.Multiply(6, 7);
// => "Multiply succeeded"

4. Test the multiplication operation for negative inputs

Modify the CalculatorTestHarness.TestMultiplication() method so that "Multiply failed for negative operands. <INNER_EXCEPTION_MESSAGE>"is returned if both integer arguments are negative (less than zero).

The <INNER_EXCEPTION_MESSAGE> placeholder should be replaced with the CalculationException's inner exception's message.

var cth = new CalculatorTestHarness(new Calculator());
cth.TestMultiplication(-2, -Int32.MaxValue);
// => "Multiply failed for negative operands. " + innerException.Message

5. Test the multiplication operation for positive inputs

Modify the CalculatorTestHarness.TestMultiplication() method so that "Multiply failed for mixed or positive operands. <INNER_EXCEPTION_MESSAGE>" is returned if at least one of the integer arguments is not negative.

The <INNER_EXCEPTION_MESSAGE> placeholder should be replaced with the CalculationException's inner exception's message.

var cth = new CalculatorTestHarness(new Calculator());
cth.TestMultiplication(Int32.MaxValue, Int32.MaxValue);
// => "Multiply failed for mixed or positive operands. " + innerException.Message