public void AcceptCoins_HavingZeroCurrentAndTotalCoins_GivenUnknown_AddUnknownToReturnCoinsAndReturnsInsertCoinMessage() { // Arrange var unknown = new Coin(.99M, .99M); // Act var result = _sut.AcceptCoins(unknown); // Assert Assert.AreEqual(decimal.Zero, SessionHelper.CurrentCoins.TotalValue()); Assert.AreEqual(decimal.Zero, SessionHelper.TotalCoins.TotalValue()); Assert.AreEqual(1, SessionHelper.ReturnCoins[Denominations.Unknown]); Assert.IsNotNull(result); Assert.AreEqual(MessageConstants.InsertCoin, result); }