IQueryable as List<T>

Question

I have a working service for retrieving books from a database, for which I am currently doing tests. The service looks like this:

public async Task<List<Book>> GetBooks()
{
   ........
   ........
   IQueryable results = repository.Query();
   var list = await Task.Factory.StartNew(() => results as List<Book>);
   return list
}

This code works great when the application is running.

During the test, I can check with the debugger that the results variable has the value I need. But list variable has null meaning. Here is the definition of my moq:

var books = new List<Book>();
for (int i = 1; i < 4; i++)
{
    books.Add(new Book
    {
        new Book { Id = i , Author = $"New Author {i}"}
    });
}

var mockBookRepository = new Mock<IBookRepository>();
mockBookRepository 
    .Setup(x => x.Query())
    .Returns(books.AsQueryable());

I need to do a test that will return values in a variable list . Changing the GetBooks () method is not valid

Answer 1

You're trying to do an invalid cast you should be materializing

public async Task<Object> GetBooks()
{
   //........
   return await repository.Query().ToListAsync()
}

PS

Make sure repository.Query() returns an IQueryable<Book> and not just IQueryable