test

Adding the test to validate the fix for an object in motion coming to a rest where the interpolator has detected no additional state updates, reset itself, and then the object starts moving again (for longer than 3-10x the tick frequency) then the time between the first new state update and the second state update should not exceed the given tick frequency if both state updates happened sequentially (tick relative).

com.unity.netcode.gameobjects/Tests/Runtime/NetworkTransform/InterpolationStopAndStartMotionTest.cs

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+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using Unity.Netcode.Components;
+using Unity.Netcode.TestHelpers.Runtime;
+using UnityEngine;
+using UnityEngine.TestTools;
+
+namespace Unity.Netcode.RuntimeTests
+{
+    [TestFixture(HostOrServer.Host, NetworkTransform.InterpolationTypes.Lerp)]
+    [TestFixture(HostOrServer.Host, NetworkTransform.InterpolationTypes.SmoothDampening)]
+    [TestFixture(HostOrServer.DAHost, NetworkTransform.InterpolationTypes.Lerp)]
+    [TestFixture(HostOrServer.DAHost, NetworkTransform.InterpolationTypes.SmoothDampening)]
+    internal class InterpolationStopAndStartMotionTest : IntegrationTestWithApproximation
+    {
+        protected override int NumberOfClients => 2;
+
+        private GameObject m_TestPrefab;
+
+        private TestStartStopTransform m_AuthorityInstance;
+        private List<TestStartStopTransform> m_NonAuthorityInstances = new List<TestStartStopTransform>();
+
+        private NetworkTransform.InterpolationTypes m_InterpolationType;
+        private List<NetworkManager> m_NetworkManagers = new List<NetworkManager>();
+        private NetworkManager m_AuthorityNetworkManager;
+
+        private int m_NumberOfUpdates;
+        private Vector3 m_Direction;
+
+        public InterpolationStopAndStartMotionTest(HostOrServer hostOrServer, NetworkTransform.InterpolationTypes interpolationType) : base(hostOrServer)
+        {
+            m_InterpolationType = interpolationType;
+        }
+
+        protected override void OnServerAndClientsCreated()
+        {
+            m_TestPrefab = CreateNetworkObjectPrefab("TestObj");
+            var testStartStopTransform = m_TestPrefab.AddComponent<TestStartStopTransform>();
+            testStartStopTransform.PositionInterpolationType = m_InterpolationType;
+            base.OnServerAndClientsCreated();
+        }
+
+        private bool WaitForInstancesToSpawn()
+        {
+            foreach (var networkManager in m_NetworkManagers)
+            {
+                if (networkManager == m_AuthorityNetworkManager)
+                {
+                    continue;
+                }
+
+                if (!networkManager.SpawnManager.SpawnedObjects.ContainsKey(m_AuthorityInstance.NetworkObjectId))
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        private bool WaitForInstancesToFinishInterpolation()
+        {
+            m_NonAuthorityInstances.Clear();
+            foreach (var networkManager in m_NetworkManagers)
+            {
+                if (networkManager == m_AuthorityNetworkManager)
+                {
+                    continue;
+                }
+
+                if (!networkManager.SpawnManager.SpawnedObjects.ContainsKey(m_AuthorityInstance.NetworkObjectId))
+                {
+                    return false;
+                }
+
+                var nonAuthority = networkManager.SpawnManager.SpawnedObjects[m_AuthorityInstance.NetworkObjectId].GetComponent<TestStartStopTransform>();
+
+                // Each non-authority instance needs to have reached their final target and reset waiting for the
+                // object to start moving again.
+                var positionInterpolator = nonAuthority.GetPositionInterpolator();
+                if (positionInterpolator.InterpolateState.Target.HasValue)
+                {
+                    return false;
+                }
+
+                if (!Approximately(nonAuthority.transform.position, m_AuthorityInstance.transform.position))
+                {
+                    return false;
+                }
+
+                m_NonAuthorityInstances.Add(nonAuthority);
+            }
+            return true;
+        }
+
+        [UnityTest]
+        public IEnumerator StopAndStartMotion()
+        {
+            m_NetworkManagers.AddRange(m_ClientNetworkManagers);
+            if (!UseCMBService())
+            {
+                m_NetworkManagers.Insert(0, m_ServerNetworkManager);
+            }
+            m_AuthorityNetworkManager = m_NetworkManagers[0];
+
+            m_AuthorityInstance = SpawnObject(m_TestPrefab, m_AuthorityNetworkManager).GetComponent<TestStartStopTransform>();
+            // Wait for all clients to spawn the instance
+            yield return WaitForConditionOrTimeOut(WaitForInstancesToSpawn);
+            AssertOnTimeout($"Not all clients spawned {m_AuthorityInstance.name}!");
+
+            ////// Start Motion
+            // Have authority move in a direction for a short period of time
+            m_Direction = GetRandomVector3(-10, 10).normalized;
+            m_NumberOfUpdates = 0;
+            m_AuthorityNetworkManager.NetworkTickSystem.Tick += NetworkTickSystem_Tick;
+
+            yield return WaitForConditionOrTimeOut(() => m_NumberOfUpdates >= 10);
+            AssertOnTimeout($"Timed out waiting for all updates to be applied to the authority instance!");
+
+            ////// Finish interpolating and wait for each interpolator to detect a stop in the motion
+            // Wait for all non-authority instances to finish interpolating to the final destination point.
+            yield return WaitForConditionOrTimeOut(WaitForInstancesToFinishInterpolation);
+            AssertOnTimeout($"Not all clients finished interpolating {m_AuthorityInstance.name}!");
+
+            // Start recording the state updates on the non-authority instances
+            foreach (var testTransform in m_NonAuthorityInstances)
+            {
+                testTransform.CheckStateUpdates = true;
+            }
+
+            ////// Stop to Start motion begins here
+            m_Direction = GetRandomVector3(-10, 10).normalized;
+            m_NumberOfUpdates = 0;
+            m_AuthorityNetworkManager.NetworkTickSystem.Tick += NetworkTickSystem_Tick;
+
+            yield return WaitForConditionOrTimeOut(() => m_NumberOfUpdates >= 10);
+            AssertOnTimeout($"Timed out waiting for all updates to be applied to the authority instance!");
+
+            // Wait for all non-authority instances to finish interpolating to the final destination point.
+            yield return WaitForConditionOrTimeOut(WaitForInstancesToFinishInterpolation);
+            AssertOnTimeout($"Not all clients finished interpolating {m_AuthorityInstance.name}!");
+
+            // Checks that the time between the first and second state update is approximately the tick frequency
+            foreach (var testTransform in m_NonAuthorityInstances)
+            {
+                var deltaVariance = testTransform.GetTimeDeltaVarience();
+                Assert.True(Approximately(deltaVariance, s_DefaultWaitForTick.waitTime), $"{testTransform.name}'s delta variance was {deltaVariance} when it should have been approximately {s_DefaultWaitForTick.waitTime}!");
+            }
+        }
+
+        /// <summary>
+        /// Moves the authority instance once per tick to simulate a change in transform state that occurs
+        /// every tick.
+        /// </summary>
+        private void NetworkTickSystem_Tick()
+        {
+            m_NumberOfUpdates++;
+            m_AuthorityInstance.transform.position = m_AuthorityInstance.transform.position + m_Direction * 2;
+            if (m_NumberOfUpdates >= 10)
+            {
+                m_AuthorityNetworkManager.NetworkTickSystem.Tick -= NetworkTickSystem_Tick;
+            }
+        }
+
+        internal class TestStartStopTransform : NetworkTransform
+        {
+
+            public bool CheckStateUpdates;
+
+            private BufferedLinearInterpolatorVector3 m_PosInterpolator;
+
+            private Dictionary<int, StateEntry> m_StatesProcessed = new Dictionary<int, StateEntry>();
+
+            public struct StateEntry
+            {
+                public float TimeAdded;
+                public BufferedLinearInterpolator<Vector3>.CurrentState State;
+            }
+
+            protected override void Awake()
+            {
+                base.Awake();
+                m_PosInterpolator = GetPositionInterpolator();
+            }
+
+            /// <summary>
+            /// Checks the time that passed between the first and second state updates.
+            /// </summary>
+            /// <returns>time passed as a float</returns>
+            public float GetTimeDeltaVarience()
+            {
+                var stateKeys = m_StatesProcessed.Keys.ToList();
+                var firstState = m_StatesProcessed[stateKeys[0]];
+                var secondState = m_StatesProcessed[stateKeys[1]];
+
+                var firstAndSecondTimeDelta = secondState.TimeAdded - firstState.TimeAdded;
+
+                // Get the delta time between the two times of both the first and second state.
+                // Then add the time it should have taken to get to the second state, and this should be the total time to interpolate
+                // from the current position to the target position of the second state update.
+                var stateDelta = (float)(secondState.State.Target.Value.TimeSent - firstState.State.Target.Value.TimeSent + secondState.State.TimeToTargetValue);
+                // Return the time detla between the time that passed and the time that should have passed processing the states.
+                return Mathf.Abs(stateDelta - firstAndSecondTimeDelta);
+            }
+
+            public override void OnUpdate()
+            {
+                base.OnUpdate();
+
+                // If we are checking the state updates, then we want to track each unique state update
+                if (CheckStateUpdates)
+                {
+                    // Make sure we have a valid target
+                    if (m_PosInterpolator.InterpolateState.Target.HasValue)
+                    {
+                        // If the state update's identifier is different
+                        var itemId = m_PosInterpolator.InterpolateState.Target.Value.ItemId;
+                        if (!m_StatesProcessed.ContainsKey(itemId))
+                        {
+                            // Add it to the table of state updates
+                            var stateEntry = new StateEntry()
+                            {
+                                TimeAdded = Time.realtimeSinceStartup,
+                                State = m_PosInterpolator.InterpolateState,
+                            };
+
+                            m_StatesProcessed.Add(itemId, stateEntry);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}