Add NotEqual acceptance test

Author: Milos

test/JsonApiDotNetCoreExampleTests/Acceptance/Spec/AttributeFilterTests.cs

@@ -105,5 +105,32 @@ public async Task Cannot_Filter_If_Explicitly_Forbidden()
             // assert
             Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
         }
+
+        [Fact]
+        public async Task Can_Filter_On_Not_Equal_Values()
+        {
+            // arrange
+            var context = _fixture.GetService<AppDbContext>();
+            var todoItems = _todoItemFaker.Generate(5); 
+            context.TodoItems.AddRange(todoItems);
+            await context.SaveChangesAsync();
+
+            var lastTodoItem = context.TodoItems.Last();
+            var httpMethod = new HttpMethod("GET");
+            var route = $"/api/v1/todo-items?filter[guid-property]=ne:{lastTodoItem.GuidProperty}";
+            var request = new HttpRequestMessage(httpMethod, route);
+
+            // act
+            var response = await _fixture.Client.SendAsync(request);
+            var body = await response.Content.ReadAsStringAsync();
+            var deserializedTodoItems = _fixture
+                .GetService<IJsonApiDeSerializer>()
+                .DeserializeList<TodoItem>(body);
+
+            // assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal(deserializedTodoItems.Count(), todoItems.Count() -1);
+            Assert.False(deserializedTodoItems.Any(i => i.GuidProperty == lastTodoItem.GuidProperty));
+        }
     }
 }