public void BookControllerTest()
{
var repository = new Mock <IBookRepository>();
var controller = new BookController(repository.Object);
controller.Book();
repository.Verify(repo => repo.GetAll(), Times.Once);
var result = controller.Book();
// Assert
var viewResult = Assert.IsType <ViewResult>(result);
var model = Assert.IsAssignableFrom <IEnumerable <BookVM> >(viewResult.ViewData.Model);
}