public void ShouldChangeBalanceAmount() { // Arrange SalesService salesService = new SalesService( this.operationTableRepository, this.balanceTableRepository, this.blockedMoneyTableRepository, this.sharesNumberTableRepository, this.blockedSharesNumberTableRepository); var testBalance = new BalanceEntity() { Id = 10, Amount = 30000.00M, Client = new ClientEntity() { Id = 10 }, Status = true }; decimal newAmount = 35000.00M; // Act bool flag = salesService.ChangeBalance(testBalance, newAmount); // Assert this.balanceTableRepository.Received(1).ChangeAmount(testBalance.Id, newAmount); this.balanceTableRepository.Received(1).SaveChanges(); if (!flag) { throw new ArgumentException("The flag is false"); } }