public async Task CheckIfOwnerOfBook_WhenBookIdHasValueAndSubscriptionIdIsNull_ShouldReturnTrue()
        {
            //arrange
            var expectedData = new List <UserBook>
            {
                new UserBook
                {
                    BookId         = Guid.Parse("484c2b84-2644-4b55-8f64-27d643286b7a"),
                    SubscriptionId = null,
                    UserId         = Guid.Parse("a7ec27ee-ac75-47f3-b4b9-9e76bcdc9c39")
                }
            };

            _bookUSerSubscriptionService.Setup(x => x.QueryAsync(It.IsAny <Expression <Func <UserBook, bool> > >(), It.IsAny <string[]>())).ReturnsAsync(expectedData);

            // Act
            var result = await _bookController.CheckIfOwnerOfBook(It.IsAny <Guid>()) as ObjectResult;

            //assert
            Assert.That(result.Value, Is.True);
        }