使用 Moq 模拟惰性接口

问题描述

我想要模拟惰性接口，但我得到 object reference not set to an instance of an object 异常.

‌这是正在测试的课程:

公共类 ProductServiceService : IProductServiceService{私有只读 Lazy<IProductServiceRepository>_存储库；私有只读 Lazy<IProductPackageRepository>_productPackageRepository；公共产品服务服务(懒惰的<IProductServiceRepository>存储库，懒惰的<IProductPackageRepository>productPackageRepository){_repository = 存储库；_productPackageRepository = productPackageRepository;}公共异步任务<OperationResult>ValidateServiceAsync(ProductServiceEntity 服务){var 错误 = 新列表<ValidationResult>();if (!await _productPackageRepository.Value.AnyAsync(p => p.Id == service.PackageId))errors.Add(new ValidationResult(string.Format(NameMessageResource.NotFoundError, NameMessageResource.ProductPackage)));...返回错误.Any()?OperationResult.Failed(errors.ToArray()): OperationResult.Success();}}

这里是测试类

[Fact, Trait("Category", "Product")]公共异步任务 Create_Service_With_Null_Financial_ContactPerson_Should_Fail(){//安排var entity = ObjectFactory.Service.CreateService(packageId: 1);var fakeProductServiceRepository = new Mock<Lazy<IProductServiceRepository>>();var repo=new Mock<IProductPackageRepository>();repo.Setup(repository => repository.AnyAsync(It.IsAny<Expression<Func<ProductPackageEntity, bool>>>()));var fakeProductPackageRepository = new Lazy<IProductPackageRepository>(() => repo.Object);var sut = new ProductServiceService(fakeProductServiceRepository.Object, fakeProductPackageRepository);//行为var 结果 = 等待 sut.AddServiceAsync(service);//断言断言.假(结果.成功)；Assert.Contains(result.ErrorMessages, error => error.Contains(string.Format(NameMessageResource.NotFoundError, NameMessageResource.ProductPackage)));}

fakeProductPackageRepository 始终为空.我关注了这篇博文，但仍然收到空引用异常.

这是您示例的重构版本:

[Fact, Trait("Category", "Product")]公共异步任务 Create_Service_With_Null_Financial_ContactPerson_Should_Fail() {//安排var entity = ObjectFactory.Service.CreateService(packageId = 1);var productServiceRepositoryMock = new Mock();var productPackageRepositoryMock = new Mock();productPackageRepositoryMock.Setup(repository => repository.AnyAsync(It.IsAny<Expression<Func<ProductPackageEntity, bool>>>())).ReturnsAsync(false);//利用 Lazy<T>(Func<T>()) 构造函数返回模拟实例var lazyProductPackageRepository = new Lazy<IProductPackageRepository>(() => productPackageRepositoryMock.Object);var lazyProductServiceRepository = new Lazy<IProductServiceRepository>(() => productServiceRepositoryMock.Object);var sut = new ProductServiceService(lazyProductServiceRepository,lazyProductPackageRepository);//行为var 结果 = 等待 sut.AddServiceAsync(service);//断言断言.假(结果.成功)；Assert.Contains(result.ErrorMessages, error => error.Contains(string.Format(NameMessageResource.NotFoundError, NameMessageResource.ProductPackage)));}

更新

以下最小、完整和可验证的示例在测试时通过.

[TestClass]公共类 MockLazyOfTWithMoqTest {[测试方法]公共异步任务 Method_Under_Test_Should_Return_True() {//安排var productServiceRepositoryMock = new Mock();var productPackageRepositoryMock = new Mock();productPackageRepositoryMock.Setup(repository => repository.AnyAsync()).ReturnsAsync(false);//利用 Lazy<T>(Func<T>()) 构造函数返回模拟实例var lazyProductPackageRepository = new Lazy<IProductPackageRepository>(() => productPackageRepositoryMock.Object);var lazyProductServiceRepository = new Lazy<IProductServiceRepository>(() => productServiceRepositoryMock.Object);var sut = new ProductServiceService(lazyProductServiceRepository,lazyProductPackageRepository);//行为var 结果 = 等待 sut.MethodUnderTest();//断言断言.IsTrue(结果);}公共接口 IProductServiceService { }公共接口 IProductServiceRepository { }公共接口 IProductPackageRepository { 任务<bool>任何异步()；}公共类 ProductServiceService : IProductServiceService {私有只读 Lazy<IProductServiceRepository>_存储库；私有只读 Lazy<IProductPackageRepository>_productPackageRepository；公共产品服务服务(懒惰的<IProductServiceRepository>存储库，懒惰的<IProductPackageRepository>productPackageRepository) {_repository = 存储库；_productPackageRepository = productPackageRepository;}公共异步任务<bool>MethodUnderTest() {var 错误 = 新列表<ValidationResult>();if (!await _productPackageRepository.Value.AnyAsync())errors.Add(new ValidationResult("error"));返回错误.Any();}}}

I want mock lazy interface but I got object reference not set to an instance of an object exception.

‌Here is class under test:

public class ProductServiceService : IProductServiceService
{
    private readonly Lazy<IProductServiceRepository> _repository;
    private readonly Lazy<IProductPackageRepository> _productPackageRepository;

    public ProductServiceService(
        Lazy<IProductServiceRepository> repository,
        Lazy<IProductPackageRepository> productPackageRepository)
    {
        _repository = repository;
        _productPackageRepository = productPackageRepository;
    }

    public async Task<OperationResult> ValidateServiceAsync(ProductServiceEntity service)
    {
        var errors = new List<ValidationResult>();

        if (!await _productPackageRepository.Value.AnyAsync(p => p.Id == service.PackageId))
            errors.Add(new ValidationResult(string.Format(NameMessageResource.NotFoundError, NameMessageResource.ProductPackage)));

       .
       .
       .

        return errors.Any()
            ? OperationResult.Failed(errors.ToArray())
            : OperationResult.Success();
    }
}

and here is test class

[Fact, Trait("Category", "Product")]
public async Task Create_Service_With_Null_Financial_ContactPerson_Should_Fail()
{
    // Arrange
    var entity = ObjectFactory.Service.CreateService(packageId: 1);

    var fakeProductServiceRepository = new Mock<Lazy<IProductServiceRepository>>();

    var repo= new Mock<IProductPackageRepository>();
    repo.Setup(repository => repository.AnyAsync(It.IsAny<Expression<Func<ProductPackageEntity, bool>>>()));
    var fakeProductPackageRepository  = new Lazy<IProductPackageRepository>(() => repo.Object);

    var sut = new ProductServiceService(fakeProductServiceRepository.Object, fakeProductPackageRepository);

    // Act
    var result = await sut.AddServiceAsync(service);

    // Assert
    Assert.False(result.Succeeded);
    Assert.Contains(result.ErrorMessages, error => error.Contains(string.Format(NameMessageResource.NotFoundError, NameMessageResource.ProductPackage)));
}

fakeProductPackageRepository always is null. I followed this blog post but still I'm getting null reference exception.

How to mock lazy initialization of objects in C# unit tests using Moq

Update: here is a screen that indicates fakeProductPackageRepository is null.

Here is a refactored version of your example:

[Fact, Trait("Category", "Product")]
public async Task Create_Service_With_Null_Financial_ContactPerson_Should_Fail() {
    // Arrange
    var entity = ObjectFactory.Service.CreateService(packageId = 1);

    var productServiceRepositoryMock = new Mock<IProductServiceRepository>();

    var productPackageRepositoryMock = new Mock<IProductPackageRepository>();
    productPackageRepositoryMock
        .Setup(repository => repository.AnyAsync(It.IsAny<Expression<Func<ProductPackageEntity, bool>>>()))
        .ReturnsAsync(false);

    //Make use of the Lazy<T>(Func<T>()) constructor to return the mock instances
    var lazyProductPackageRepository = new Lazy<IProductPackageRepository>(() => productPackageRepositoryMock.Object);
    var lazyProductServiceRepository = new Lazy<IProductServiceRepository>(() => productServiceRepositoryMock.Object);

    var sut = new ProductServiceService(lazyProductServiceRepository, lazyProductPackageRepository);

    // Act
    var result = await sut.AddServiceAsync(service);

    // Assert
    Assert.False(result.Succeeded);
    Assert.Contains(result.ErrorMessages, error => error.Contains(string.Format(NameMessageResource.NotFoundError, NameMessageResource.ProductPackage)));
}

UPDATE

The following Minimal, Complete, and Verifiable example of your stated issue passes when tested.

[TestClass]
public class MockLazyOfTWithMoqTest {
    [TestMethod]
    public async Task Method_Under_Test_Should_Return_True() {
        // Arrange
        var productServiceRepositoryMock = new Mock<IProductServiceRepository>();

        var productPackageRepositoryMock = new Mock<IProductPackageRepository>();
        productPackageRepositoryMock
            .Setup(repository => repository.AnyAsync())
            .ReturnsAsync(false);

        //Make use of the Lazy<T>(Func<T>()) constructor to return the mock instances
        var lazyProductPackageRepository = new Lazy<IProductPackageRepository>(() => productPackageRepositoryMock.Object);
        var lazyProductServiceRepository = new Lazy<IProductServiceRepository>(() => productServiceRepositoryMock.Object);

        var sut = new ProductServiceService(lazyProductServiceRepository, lazyProductPackageRepository);

        // Act
        var result = await sut.MethodUnderTest();

        // Assert
        Assert.IsTrue(result);
    }

    public interface IProductServiceService { }
    public interface IProductServiceRepository { }
    public interface IProductPackageRepository { Task<bool> AnyAsync();}

    public class ProductServiceService : IProductServiceService {
        private readonly Lazy<IProductServiceRepository> _repository;
        private readonly Lazy<IProductPackageRepository> _productPackageRepository;

        public ProductServiceService(
            Lazy<IProductServiceRepository> repository,
            Lazy<IProductPackageRepository> productPackageRepository) {
            _repository = repository;
            _productPackageRepository = productPackageRepository;
        }

        public async Task<bool> MethodUnderTest() {
            var errors = new List<ValidationResult>();

            if (!await _productPackageRepository.Value.AnyAsync())
                errors.Add(new ValidationResult("error"));

            return errors.Any();
        }
    }
}

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