public void FieldAuth_WithPolicyAndRoles_DescriptorNull()
        {
            // arrange
            // act
            Action action = () =>
                            AuthorizeObjectFieldDescriptorExtensions
                            .Authorize(null, "MyPolicy", new[] { "MyRole" });

            // assert
            Assert.Throws <ArgumentNullException>(action);
        }
        public void FieldAuth_DefaultPolicy_DescriptorNull()
        {
            // arrange
            // act
            Action action = () =>
                            AuthorizeObjectFieldDescriptorExtensions
                            .Authorize(null);

            // assert
            Assert.Throws <ArgumentNullException>(action);
        }