public async Task FinishRentalOnGet_WhenEntityExistsAndIsRented_ReturnsRedirectToIndex()
{
//Arrange
TestDbSeeder.Initialize(_db);
TestDbSeeder.SeedBooks(_db);
TestDbSeeder.SeedRentals(_db);
//Act
var bookId = 1;
var result = await _controller.FinishRental(bookId);
//Assert
var book = await _db.Books.Include(b => b.Rentals).FirstOrDefaultAsync(b => b.Id == bookId);
Assert.NotNull(book);
Assert.Equal(Status.Available, book.Status);
var lastRental = await _db.Rentals
.Where(r => r.BookId == bookId)
.OrderByDescending(r => r.BeginDate)
.FirstOrDefaultAsync();
Assert.NotNull(lastRental);
Assert.NotNull(lastRental.EndDate);
var redirectToActionResult = Assert.IsType <RedirectToActionResult>(result);
Assert.Null(redirectToActionResult.ControllerName);
Assert.Equal(nameof(RentalsController.AvailableBooks), redirectToActionResult.ActionName);
}