public void InvoiceBLLCount()
{
var data = new List <Invoice>
{
new Invoice()
}.AsQueryable();
var mockSet = new Mock <DbSet <Invoice> >();
mockSet.As <IQueryable <Invoice> >().Setup(m => m.Provider).Returns(data.Provider);
mockSet.As <IQueryable <Invoice> >().Setup(m => m.Expression).Returns(data.Expression);
mockSet.As <IQueryable <Invoice> >().Setup(m => m.ElementType).Returns(data.ElementType);
mockSet.As <IQueryable <Invoice> >().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());
var mockContext = new Mock <OfficeStoreContext>();
mockContext.Setup(c => c.Invoice).Returns(mockSet.Object);
var service = new InvoiceBLL(mockContext.Object);
Assert.IsTrue(service.InvoiceCount() == 1);
}