test: implement extra features on top of existing NetworkUpdateLoopTests to cover other test cases (#559)

* implement extra features on top of existing tests to cover other test cases too

* minor update

Author: 0xFA11

com.unity.multiplayer.mlapi/Tests/Runtime/NetworkUpdateLoopTests.cs

@@ -224,6 +224,14 @@ private void Awake()
                 this.RegisterNetworkUpdate(NetworkUpdateStage.FixedUpdate);
                 this.RegisterNetworkUpdate(NetworkUpdateStage.PreUpdate);
                 this.RegisterNetworkUpdate(NetworkUpdateStage.PreLateUpdate);
+                this.RegisterNetworkUpdate(NetworkUpdateStage.PostLateUpdate);
+
+                // intentionally try to register for 'PreUpdate' stage twice
+                // it should be ignored and the instance should not be registered twice
+                // otherwise test would fail because it would call 'OnPreUpdate()' twice
+                // which would ultimately increment 'netUpdates[idx]' integer twice
+                // and cause 'Assert.AreEqual()' to fail the test
+                this.RegisterNetworkUpdate(NetworkUpdateStage.PreUpdate);
             }
 
             public void NetworkUpdate(NetworkUpdateStage updateStage)
@@ -239,6 +247,9 @@ public void NetworkUpdate(NetworkUpdateStage updateStage)
                     case NetworkUpdateStage.PreLateUpdate:
                         UpdateCallbacks.OnPreLateUpdate();
                         break;
+                    case NetworkUpdateStage.PostLateUpdate:
+                        UpdateCallbacks.OnPostLateUpdate();
+                        break;
                 }
             }
 
@@ -269,7 +280,8 @@ public IEnumerator UpdateStagesMixed()
             const int kNetFixedUpdateIndex = 0;
             const int kNetPreUpdateIndex = 1;
             const int kNetPreLateUpdateIndex = 2;
-            int[] netUpdates = new int[3];
+            const int kNetPostLateUpdateIndex = 3;
+            int[] netUpdates = new int[4];
             const int kMonoFixedUpdateIndex = 0;
             const int kMonoUpdateIndex = 1;
             const int kMonoLateUpdateIndex = 2;
@@ -304,6 +316,14 @@ public IEnumerator UpdateStagesMixed()
                             netUpdates[kNetPreLateUpdateIndex]++;
                             Assert.AreEqual(monoUpdates[kMonoLateUpdateIndex] + 1, netUpdates[kNetPreLateUpdateIndex]);
                         }
+                    },
+                    OnPostLateUpdate = () =>
+                    {
+                        if (isTesting)
+                        {
+                            netUpdates[kNetPostLateUpdateIndex]++;
+                            Assert.AreEqual(netUpdates[kNetPostLateUpdateIndex], netUpdates[kNetPreLateUpdateIndex]);
+                        }
                     }
                 };
                 gameScript.BehaviourCallbacks = new MonoBehaviourCallbacks