TDD插入到數據庫

Question

我一直在閱讀關於TDD的文章，並且我看到很多關於不做任何數據庫事務的文章，因爲「單獨的，沒有依賴關係的代碼塊」。

所以現在我有一點兩難 - 我希望能夠測試我的服務層方法AddNewStudent實際上是否有效。此方法進入我的DbContext，然後向數據庫中添加一條新記錄。如果數據庫操作不建議用於TDD，那麼除了僅僅在瀏覽器上測試我的應用程序外，我還可以測試AddNewStudent方法嗎？

public class StudentManager : ManagerBase 
{ 
    internal StudentManager() { } 

    public Student AddNewStudent(string fName, string lName, DateTime dob) 
    { 
     // Create a student model instance using factory 
     var record = Factories.StudentFac.CreateOne(fName, lName, dob); 

     DbContext.Students.Add(record); 
     DbContext.SaveChanges(); 

     return record; 
    } 
} 

而且我的測試看起來像這樣

[TestMethod] 
public void StudentManager_AddNewStudent_Test() 
{ 
    var fName = "Ryan"; 
    var lName = "Rigil"; 
    var dob = DateTime.Parse("3/1/2006"); 

    var student = Managers.StudentManager.AddNewStudent(fName, lName, dob); 

    Assert.AreEqual(fName, student.FirstName); 
    Assert.AreEqual(lName, student.LastName); 
    Assert.AreEqual(dob.ToShortDateString(), student.DoB.ToShortDateString()); 
} 

Answer 1

你StudentManager具有內部埋藏的依賴，使其難以測試。考慮重構您的設計以實現更好的可測試性。

望着StudentManager以下假設，推導出...

//An assumed abstraction of the ManagerBase 
public abstract class ManagerBase { 
    public ManagerBase(IDbContext dbContext, IFactory factories) { 
     DbContext = dbContext; 
     Factories = factories; 
    } 
    public IDbContext DbContext { get; private set; } 
    public IFactory Factories { get; private set; } 
} 

//An abstraction of what the unit of work would look like 
public interface IDbContext { 
    //student repository 
    DbSet<Student> Students { get; } 
    //...other repositories 
    int SaveChanges(); 
} 

//Just an example of the Student Factory. 
public interface IModelFactory<T> where T : class, new() { 
    T Create(Action<T> configuration); 
} 

public interface IFactory { 
    IModelFactory<Student> StudentFac { get; } 
    //...other factories. Should try to make your factories Generic 
} 

與目標類refactors到...

public class StudentManager : ManagerBase { 
    public StudentManager(IDbContext dbContext, IFactory factories) : base(dbContext, factories) { } 

    public Student AddNewStudent(string fName, string lName, DateTime dob) { 
     // Create a student model instance using factory 
     var record = Factories.StudentFac.Create(r => { 
      r.FirstName = fName; 
      r.LastName = lName; 
      r.DoB = dob; 
     }); 

     base.DbContext.Students.Add(record); 
     base.DbContext.SaveChanges(); 

     return record; 
    } 
} 

雖然它可能看起來不起眼，將大大有助於代碼的可測試性。

像Moq嘲弄的框架，現在可以用於創建數據庫訪問和工廠仿版...

[TestMethod] 
public void StudentManager_Should_AddNewStudent() { 
    //Arrange: setup/initialize the dependencies of the test 
    var fName = "Ryan"; 
    var lName = "Rigil"; 
    var dob = DateTime.Parse("3006-01-03"); 

    //using Moq to create mocks/fake of dependencies 
    var dbContextMock = new Mock<IDbContext>(); 

    //Extension method used to create a mock of DbSet<T> 
    var dbSetMock = new List<Student>().AsDbSetMock(); 
    dbContextMock.Setup(x => x.Students).Returns(dbSetMock.Object); 

    var factoryMock = new Mock<IFactory>(); 
    factoryMock 
     .Setup(x => x.StudentFac.Create(It.IsAny<Action<Student>>())) 
     .Returns<Action<Student>>(a => { 
      var s = new Student(); 
      a(s); 
      return s; 
     }); 

    //this is the system/class under test. 
    //while this is being created manually, you should look into 
    //using DI/IoC container to manage Dependency Injection 
    var studentManager = new StudentManager(dbContextMock.Object, factoryMock.Object); 

    //Act: here we actually test the method 
    var student = studentManager.AddNewStudent(fName, lName, dob); 

    //Assert: and check that it executed as expected 
    Assert.AreEqual(fName, student.FirstName); 
    Assert.AreEqual(lName, student.LastName); 
    Assert.AreEqual(dob.ToShortDateString(), student.DoB.ToShortDateString()); 
} 

對於生產，你可以創建接口的正確實施，並將其注入到類這取決於他們。此答案完全基於您在帖子中提供的示例。花點時間瞭解使用的概念，並在網上做更多的研究。隨着您在TDD中的進展，您可以將這些概念與您項目的其餘部分一起應用。