public void TestMockingSumService()
{
var value1 = 10;
var value2 = 10;
var operation = Operation.Sum;
// Here the expected value is different from the sum between value1 and value2 just to show
// Sum() will not be called actually. The mocked object will return a preprogramed value.
var expectedValue = -1;
_calculatorService = new CalculatorService(_mockedSumService, _subtractionService);
// For any values received as parameter, Sum() will return the expectedValue.
_mockedSumService.Sum(Arg.Any <int>(), Arg.Any <int>())
.ReturnsForAnyArgs(expectedValue);
var result = _calculatorService.ProcessOperation(value1, value2, operation);
result.ShouldBe(expectedValue, $"Wrong answer! Result should be {expectedValue}, {result} was found.");
// Asserts Sum() was called once.
_mockedSumService.Received(1).Sum(Arg.Any <int>(), Arg.Any <int>());
}
