Question

我正在学习xUnit Test，并且在运行测试用例时遇到了此类错误：

System.NullReferenceException : Object reference not set to an instance of an object.

我在网上搜索，但似乎没有任何效果。以下是我的代码：

Controller

public class AuthorsController : ControllerBase
    {
        private readonly IRepositoryWrapper Wrapper;
        private readonly ILoggerManager Logger;

        public AuthorsController(ILoggerManager logger, IRepositoryWrapper wrapper)
        {
            Wrapper = wrapper;
            Logger = logger;
        }

        public AuthorsController(IRepositoryWrapper wrapper)
        {
            Wrapper = wrapper;
        }

        [HttpGet]
        public async Task<IActionResult> GetAuthors()
        {
            try
            {
                var authors = await Wrapper.Author.GetAllAuthorsAsync();
                Logger.LogInfo($"Returned all authors from database.");
                return Ok(authors);
            }
            catch (Exception ex)
            {
                Logger.LogError($"Error: {ex}");
                return StatusCode(500, "Internal server error");
            }
        }

        [HttpGet("{id}")]
        public async Task<IActionResult> GetAuthorByID(int id)
        {
            try
            {
                var author = await Wrapper.Author.GetAuthorByIdAsync(id);
                if (author == null)
                {
                    Logger.LogError($"Author with ID {id} NOT FOUND");
                    return NotFound();
                }
                else
                {
                    Logger.LogInfo($"Returned author with ID {id}");
                    return Ok(author);
                }
            }
            catch (Exception ex)
            {
                Logger.LogError($"Error: {ex}");
                return StatusCode(500, "Internal server error");
            }
        }
}

RepositoryWrapper Class包含2个存储库，分别是AuthorRepository和BookRepository，由于测试用例与作者有关，因此我只发布了AuthorRepository代码。

public AuthorRepository(RepositoryContext repositoryContext)
            : base(repositoryContext)
        { }

        public async Task<IEnumerable<Author>> GetAllAuthorsAsync()
        {
            var authors = await FindAll()
                                .OrderBy(a => a.AuthorName)
                                .Include(a => a.Books)
                                .ToListAsync();
            return authors;
        }

        public async Task<Author> GetAuthorByIdAsync(int AuthorID)
        {
            var author = await FindByCondition(b => b.AuthorID
                             .Equals(AuthorID))
                             .Include(a => a.Books)
                             .SingleOrDefaultAsync();
            return author;
        }

xUnit Test Case

public class AuthorsTest
    {
        //Arrange
        private readonly AuthorsController Controller;
        readonly RepositoryWrapper repository;

        public AuthorsTest()
        {
            Controller = new AuthorsController(repository);
        }

        //Test 1 - Return Ok Response when get authors
        [Fact]
        public void GetAuthors_OkResult()
        {
            //Act
            var okResult = Controller.GetAuthors().Result;

            //Assert
            Assert.IsType<OkObjectResult>(okResult);
        }

        //Test 2 - Return all authors when get authors
        [Fact]
        public void GetAuthors_ReturnsAll()
        {
            //Act
            var okResult = Controller.GetAuthors().Result as OkObjectResult;

            //Assert
            var authors = Assert.IsType<List<Author>>(okResult.Value);
            Assert.Equal(2, authors.Count());
        }

        //Test 3 - Return NotFound Response on invalid AuthorID
        [Fact]
        public void GetAuthorByID_ReturnNotFound()
        {
            //Act
            var notFoundResult = Controller.GetAuthorByID(10);

            //Assert
            Assert.IsType<NotFoundResult>(notFoundResult.Result);
        }

        //Test 4 - Return Ok Response when get author by ID
        [Fact]
        public void GetAuthorByID_ReturnOkResult()
        {
            //Act
            var okResult = Controller.GetAuthorByID(6);

            //Assert
            Assert.IsType<OkObjectResult>(okResult.Result);
        }

        //Test 5 - Return selected author when get author by ID
        [Fact]
        public void GetAuthorByID_ReturnAuthor()
        {
            //Act
            var okResult = Controller.GetAuthorByID(6).Result as OkObjectResult;

            //Assert
            Assert.IsType<Author>(okResult.Value);
            Assert.Equal(6, (okResult.Value as Author).AuthorID);
        }
}

请帮助解决错误，因为我不知道如何发生，因为我一直在遵循网络上的教程。谢谢。

.NET Core Web API上的xUnit测试错误：对象引用未设置为对象的实例

0 个答案: