public void BeAbleToAddItsEarningsToExistingEarningsValueGivenFromAndToDates() { IDictionary <Provider, double> earningsPerProvider = new Dictionary <Provider, double>(); Payment newPayment = CreatePayment(); double expectedValue = 2000; double overallValue = 0; newPayment.AddThisPaymentsEarningsToOverallValue(ref overallValue, DateTime.Today, DateTime.Today); Assert.AreEqual(expectedValue, overallValue); }