Visual Studio 2022 - Getting 'Object reference not set to an instance of an object' Error When Running Unit Tests with Moq
I'm migrating some code and I've been struggling with this for a few days now and could really use some help..... I'm encountering an 'Object reference not set to an instance of an object' error when trying to run unit tests using Moq in Visual Studio 2022. The tests are written for a service that interacts with a repository, and I'm mocking the repository interface. Here's a snippet of my code: ```csharp public interface IRepository { Task<MyEntity> GetEntityAsync(int id); } public class MyService { private readonly IRepository _repository; public MyService(IRepository repository) { _repository = repository; } public async Task<MyEntity> GetEntity(int id) { return await _repository.GetEntityAsync(id); } } [TestClass] public class MyServiceTests { private Mock<IRepository> _mockRepo; private MyService _service; [TestInitialize] public void Setup() { _mockRepo = new Mock<IRepository>(); _service = new MyService(_mockRepo.Object); } [TestMethod] public async Task GetEntity_ReturnsEntity_WhenIdIsValid() { // Arrange var entity = new MyEntity { Id = 1, Name = "Test Entity" }; _mockRepo.Setup(repo => repo.GetEntityAsync(1)).ReturnsAsync(entity); // Act var result = await _service.GetEntity(1); // Assert Assert.IsNotNull(result); Assert.AreEqual(entity.Name, result.Name); } } ``` When I run the tests, I get the error on the line where I'm setting up the mock. I've confirmed that the repository is properly mocked and that the method is being set up correctly. I've also ensured that the test initialization is running as expected. This issue seems to arise only in certain test cases, specifically when the `GetEntityAsync` method is being called. I've tried cleaning and rebuilding the solution, and I've also checked if there are any null reference issues in the `MyEntity` class. The Moq version I'm using is 4.16.1, and I've verified that all dependencies are updated to their latest versions. Is there something I'm missing or a best practice I should follow when working with mocks in this context? This is happening in both development and production on macOS. Is this even possible?