Unity TestRunner批量运行测试失败，单独运行正常问题求助

使用Unity 2020.3.11f1版本，SpawnMultipleBlocks测试用例单独运行时可正常通过，但通过TestRunner点击“Run All”批量运行时始终失败。该测试负责在场景中按随机间隔生成方块。

报错信息 #

SpawnMultipleBlocks (0.020s)
---
Unhandled log message: '[Exception] NullReferenceException: Object reference not set to an instance of an object'. Use UnityEngine.TestTools.LogAssert.Expect
---
BlockSpawner+<SpawnedBlocks>d__14.MoveNext () (at Assets/Scripts/BlockSpawner.cs:69)
UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) (at <127e81e1cb3441cc97d26b1910daae77>:0)
UnityEngine.MonoBehaviour:StartCoroutine(IEnumerator)
BlockSpawner:Start() (at Assets/Scripts/BlockSpawner.cs:24)
---
topPos is null
Generate at top : 0
NullReferenceException: Object reference not set to an instance of an object
topPos is null
Generate at top : 0
NullReferenceException: Object reference not set to an instance of an object
topPos is null
Generate at top : 0
NullReferenceException: Object reference not set to an instance of an object

测试类代码（BlockSpawnerTests.cs） #

using System.Collections;
using NUnit.Framework;
using UnityEditor;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.TestTools;

namespace Tests
{

    public class BlockSpawnerTests : MonoBehaviour
    {
        private static string resourceDirPath = "Tests/Block";

        [Test]
        public void SpawnBlock()
        {
            // Arrange
            var spawner = new GameObject().AddComponent<BlockSpawner>();
            spawner.setBlockReference(Resources.Load<GameObject>(resourceDirPath));

            // Act
            spawner.SpawnBlock(Vector3.zero);

            // Assert
            Assert.IsNotNull(spawner.getSpawnedBlock());
        }

        [Test]
        public void SpawnBlockAtPosition()
        {
            // Arrange
            var spawner = new GameObject().AddComponent<BlockSpawner>();
            spawner.setBlockReference(Resources.Load<GameObject>("Tests/Block"));

            // Act
            spawner.SpawnBlock(Vector3.one);

            // Assert
            Assert.AreEqual(spawner.getSpawnedBlock().transform.position, Vector3.one);
        }

        [Test]
        public void SpawnBlockSpeed()
        {
            // Arrange
            var spawner = new GameObject().AddComponent<BlockSpawner>();
            spawner.setBlockReference(Resources.Load<GameObject>("Tests/Block"));

            // Act
            spawner.SpawnBlock(Vector3.zero);

            // Assert
            Assert.IsTrue(spawner.getSpawnedBlock().GetComponent<Block>().GetSpeed() >= -10
                && spawner.getSpawnedBlock().GetComponent<Block>().GetSpeed() <= -4);
        }

        [Test]
        public void WhenBlockComponentIsNullShouldLog()
        {
            // Arrange
            var spawner = new GameObject().AddComponent<BlockSpawner>();
            spawner.setBlockReference(new GameObject("EmptyObject"));

            // Act
            spawner.SpawnBlock(Vector3.zero);

            // Assert
            LogAssert.Expect(LogType.Log, "Spawned block doesn't have a Block component");
            LogAssert.NoUnexpectedReceived();
            Destroy(spawner);
        }

        [UnityTest]
        public IEnumerator SpawnMultipleBlocks()
        {
            Debug.Log("block spawner create");
            var spawner = new GameObject();
            var blockSpawner = spawner.AddComponent<BlockSpawner>();
            Debug.Log("set top bottom middle");
            blockSpawner.SetTopPos(new GameObject().transform);
            blockSpawner.SetBottomPos(new GameObject().transform);
            blockSpawner.SetMiddlePos(new GameObject().transform);

            blockSpawner.SetWaitForSpawnLow(1);
            blockSpawner.SetWaitForSpawnHigh(2);
            blockSpawner.setBlockReference(Resources.Load<GameObject>("Tests/Block"));
            yield return new WaitForSeconds(1);
            blockSpawner.Start();

            // wait for at least 1 block to be spawned
            yield return new WaitForSeconds(1);
            Assert.GreaterOrEqual(blockSpawner.GetSpawnedBlocks().Count, 1);

            // wait for at least 2 block to be spawned
            yield return new WaitForSeconds(1);
            Assert.GreaterOrEqual(blockSpawner.GetSpawnedBlocks().Count, 2);
        }
    }
}

核心原因 #

1. 临时对象被提前回收：批量运行时，Unity测试的场景清理机制会自动回收未被持有引用的临时GameObject，SpawnMultipleBlocks中创建的top/bottom/middle定位对象没有被保存引用，导致topPos等变量变为null，触发空引用异常。单独运行时测试环境的生命周期管理更宽松，临时对象能保持到测试结束。
2. 测试类不必要的继承：测试类继承MonoBehaviour是多余的，NUnit测试类不需要该继承，反而可能干扰测试的生命周期管理逻辑。
3. 测试间状态污染：没有统一的测试清理逻辑，前序测试生成的对象可能影响后续测试的运行环境。

修复步骤 #

1. 移除测试类的MonoBehaviour继承
   修改测试类定义，去掉不必要的继承：

   public class BlockSpawnerTests // 移除: MonoBehaviour
   

2. 保留临时定位对象的引用
   在SpawnMultipleBlocks中保存定位对象的引用，防止被自动回收，并在测试结束后手动清理：

   [UnityTest]
   public IEnumerator SpawnMultipleBlocks()
   {
       Debug.Log("block spawner create");
       var spawner = new GameObject();
       var blockSpawner = spawner.AddComponent<BlockSpawner>();
       Debug.Log("set top bottom middle");
       
       // 保存临时对象引用，避免被自动回收
       var topObj = new GameObject();
       var bottomObj = new GameObject();
       var middleObj = new GameObject();
       
       blockSpawner.SetTopPos(topObj.transform);
       blockSpawner.SetBottomPos(bottomObj.transform);
       blockSpawner.SetMiddlePos(middleObj.transform);
   
       blockSpawner.SetWaitForSpawnLow(1);
       blockSpawner.SetWaitForSpawnHigh(2);
       blockSpawner.setBlockReference(Resources.Load<GameObject>("Tests/Block"));
       yield return new WaitForSeconds(1);
       blockSpawner.Start();
   
       // 等待至少1个方块生成
       yield return new WaitForSeconds(1);
       Assert.GreaterOrEqual(blockSpawner.GetSpawnedBlocks().Count, 1);
   
       // 等待至少2个方块生成
       yield return new WaitForSeconds(1);
       Assert.GreaterOrEqual(blockSpawner.GetSpawnedBlocks().Count, 2);
   
       // 测试结束后手动清理所有对象
       Destroy(spawner);
       Destroy(topObj);
       Destroy(bottomObj);
       Destroy(middleObj);
   }
   

3. 添加统一测试清理逻辑
   新增TearDown方法，确保每个测试结束后清理场景中的测试对象，避免状态污染：

   [TearDown]
   public void TearDown()
   {
       // 销毁所有测试生成的BlockSpawner
       foreach (var spawner in Object.FindObjectsOfType<BlockSpawner>())
       {
           Destroy(spawner.gameObject);
       }
       // 销毁所有生成的方块
       foreach (var block in Object.FindObjectsOfType<Block>())
       {
           Destroy(block.gameObject);
       }
   }
   

4. 优化BlockSpawner的启动逻辑
   若BlockSpawner的Start方法是默认MonoBehaviour生命周期方法，建议将生成逻辑移到单独的公共方法（如StartSpawning），避免测试初始化完成前自动执行导致空引用：

   // 在BlockSpawner中新增方法
   public void StartSpawning()
   {
       StartCoroutine(SpawnedBlocks());
   }
   // 测试中调用该方法代替Start()
   blockSpawner.StartSpawning();
   

内容的提问来源于stack exchange，提问作者Chathuranga Jayanath