public void Should_valldate_input()
{
var validator = new ValidatorSpy();
var m = new MultiplierProgram(validator);
Assert.Throws <Exception>(() => m.Process("abc"));
Assert.That(validator.WasCalled, Is.True);
}
public void Should_validate_input()
{
var validatorSpy = new ValidatorSpy();
var a = new AdderProgram(validatorSpy);
var ex = Assert.Throws <Exception>(() => a.Process("a"));
Assert.That(validatorSpy.WasCalled, Is.True);
Assert.That(ex.Message, Does.Contain("Invalid input: must be comma separated list of numbers"));
}