I am new to using Mock test in .Net.
I am testing out a financial transaction which is of the following nature:

int  amt =20;
//sets all the props and func and returns a FinaceAccount.
//Note I did not SetUp the amt of the account.
var account =GetFinanceAccount() 


//service layer to be tested
_financeService.tranx(account,amt);

//checks if the amt was added to the account.amt
//here the amt comes out same as that set in GetFinanceAccount.
Assert.AreEqual(account.amt ,amt)  

I know that the function tranx works correctly but there is an issue with the test. Are there any GOOD reference material on Mocking in .Net