public void InvoiceBLLHasItemMethod() { //Arrange var data = new List <Items> { new Items() { Id = "1", Quantity = 12, OriginalPrice = 1, SalesPrice = 2, ProductName = "Pen", Status = "Factory New" } }.AsQueryable(); var mockSet = new Mock <DbSet <Items> >(); mockSet.As <IQueryable <Items> >().Setup(m => m.Provider).Returns(data.Provider); mockSet.As <IQueryable <Items> >().Setup(m => m.Expression).Returns(data.Expression); mockSet.As <IQueryable <Items> >().Setup(m => m.ElementType).Returns(data.ElementType); mockSet.As <IQueryable <Items> >().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator()); var mockContext = new Mock <OfficeStoreContext>(); mockContext.Setup(c => c.Items).Returns(mockSet.Object); InvoiceBLL invoiceBLL = new InvoiceBLL(mockContext.Object); // Act bool HasNotItem = invoiceBLL.HasNotItem("1"); //Assert Assert.IsFalse(HasNotItem); }