public async Task SubscribeTag_WithNoClientSecret() { var result = await realtime.CreateTag("csharp"); AssertMissingClientSecretUrlParameter(result); // This is where Instagram tries to call your callback, without implementing the pubhubsub implementatin that authenticates, it will fail try { var result2 = await realtime.CreateTag(""); } catch (Exception exception) { Assert.IsInstanceOfType(exception, typeof(ArgumentException)); } }