public void Returns2CatalogItemsWithSameBrandAndTypeId()
    {
        var spec = new eShopWeb.ApplicationCore.Specifications.CatalogFilterPaginatedSpecification(0, 10, 1, 1);

        var result = GetTestCollection()
                     .AsQueryable()
                     .Where(spec.WhereExpressions.FirstOrDefault().Filter);

        Assert.NotNull(result);
        Assert.Equal(2, result.ToList().Count);
    }
        public void ReturnsAllCatalogItems()
        {
            var spec = new eShopWeb.ApplicationCore.Specifications.CatalogFilterPaginatedSpecification(0, 10, null, null);

            var result = GetTestCollection()
                         .AsQueryable()
                         .Where(spec.WhereExpressions.FirstOrDefault());

            Assert.NotNull(result);
            Assert.Equal(4, result.ToList().Count);
        }