EF Moq Unit Test, unsure verify

I am totally new to unit tests. I read many "tutorials" from different people and I decided to use msdn solutions.

I use this https://msdn.microsoft.com/en-us/library/dn314429(v=vs.113).aspx as my test, I am interested in "Testing non-query scenarios" there.

According to this article, I tried to test my simple CRUD's Create() action.

Here's my code (FinancialAssistantEntities is my DbContext (EF Database First)):

Context:

public partial class FinancialAssistantEntities : DbContext
{
    public FinancialAssistantEntities()
        : base("name=FinancialAssistantEntities")
    {
    }
    .
    .
    .
    public virtual DbSet<FAWallet> FAWallet { get; set; }
}

Repository method: (I commented out my transaction's using, because running it from test method causes the error "No connection string named 'FinancialAssistantEntities' could be found in the application config file."),

public async Task<bool> CreateWallet(FAWallet model)
{
    using (var context = Context)
    {
        // transaction with IsolationLevel
        //using (var tran = context.Database.BeginTransaction(IsolationLevel.ReadUncommitted))
        {
            try
            {                       
                context.FAWallet.Add(model);
                //context.SaveChanges();
                await context.SaveChangesAsync();
                //tran.Commit();
                return true;
            }
            catch (Exception ex)
            {
                //tran.Rollback();
                throw ex;
            }
        }
    }
}

TestMethod:

[TestMethod]
public void CreateWalletTest()
{
    var wallet = new FAWallet()
    {
        WalletId = Guid.NewGuid(),
        //WalletName = StringHelper.GenerateRandomString(12),
        // admin ID
        WalletUserId = "e6888245-1d9b-431c-a068-aa62932e47ec",
        WalletCreateDate = DateTime.Now,
        WalletEnabled = true
    };

    var mockSet = new Mock<DbSet<FAWallet>>();

    var mockContext = new Mock<FinancialAssistantEntities>();
    mockContext.Setup(x => x.FAWallet).Returns(mockSet.Object);

    var walletRepository = new FAWalletRepository(mockContext.Object);
    walletRepository.CreateWallet(wallet).Wait();

    mockSet.Verify(x => x.Add(It.IsAny<FAWallet>()), Times.Once());
    mockContext.Verify(x => x.SaveChangesAsync(), Times.Once()); 
}

First of all, I don't know if commenting transaction's using out is good idea, though I don't know much about testing yet.

Secondly, my test always passes. I even commented out the WalletName property's set, since this field is not-nullable, so it seems I made sth wrong.