4-实体框架单元测试层

在单元测试层中，我们通常测试业务层功能。为了做到这一点，我们将删除数据层（实体框架）依赖项。

现在的问题是：如何删除实体框架依赖关系以便对业务层功能进行单元测试？

答案很简单：我们将为 IDbRepository 接口提供一个假实现，然后我们可以进行单元测试

4-1 实现基本接口（假实现）

class FakeDbRepository : IDbRepository
{
    #region Protected Members

    protected Hashtable _dbContext;
    protected int _numberOfRowsAffected;
    protected Hashtable _contextFunctionsResults;

    #endregion Protected Members

    #region Constractors

    public FakeDbRepository(Hashtable contextFunctionsResults = null)
    {
        _dbContext = new Hashtable();
        _numberOfRowsAffected = 0;
        _contextFunctionsResults = contextFunctionsResults;
    }

    #endregion Constractors

    #region IRepository Implementation

    #region Tables and Views functions

    public IQueryable<TResult> GetAll<TResult>(bool noTracking = true) where TResult : class
    {
        return GetDbSet<TResult>().AsQueryable();
    }

    public TEntity Add<TEntity>(TEntity entity) where TEntity : class
    {
        GetDbSet<TEntity>().Add(entity);
        ++_numberOfRowsAffected;
        return entity;
    }

    public TEntity Delete<TEntity>(TEntity entity) where TEntity : class
    {
        GetDbSet<TEntity>().Remove(entity);
        ++_numberOfRowsAffected;
        return entity;
    }

    public TEntity Attach<TEntity>(TEntity entity) where TEntity : class
    {
        return Add(entity);
    }

    public TEntity AttachIfNot<TEntity>(TEntity entity) where TEntity : class
    {
        if (!GetDbSet<TEntity>().Contains(entity))
            return Attach(entity);

        return entity;
    }

    #endregion Tables and Views functions

    #region Transactions Functions

    
    public virtual int Commit()
    {
        var numberOfRowsAffected = _numberOfRowsAffected;
        _numberOfRowsAffected = 0;
        return numberOfRowsAffected;
    }

    public virtual Task<int> CommitAsync(CancellationToken cancellationToken = default(CancellationToken))
    {
        var numberOfRowsAffected = _numberOfRowsAffected;
        _numberOfRowsAffected = 0;
        return new Task<int>(() => numberOfRowsAffected);
    }

    #endregion Transactions Functions

    #region Database Procedures and Functions

    public virtual TResult Execute<TResult>(string functionName, params object[] parameters)
    {
        if (_contextFunctionsResults != null && _contextFunctionsResults.Contains(functionName))
            return (TResult)_contextFunctionsResults[functionName];

        throw new NotImplementedException();
    }

    #endregion Database Procedures and Functions

    #endregion IRepository Implementation

    #region IDisposable Implementation

    public void Dispose()
    {

    }

    #endregion IDisposable Implementation

    #region Private Functions

    private List<TEntity> GetDbSet<TEntity>() where TEntity : class
    {
        if (!_dbContext.Contains(typeof(TEntity)))
            _dbContext.Add(typeof(TEntity), new List<TEntity>());

        return (List<TEntity>)_dbContext[typeof(TEntity)]; 
    }

    #endregion Private Functions
}

4-2 运行单元测试

[TestClass]
public class ProductUnitTest
{
    [TestMethod]
    public void TestInsertForNewCategory()
    {
        // Initialize repositories
        FakeDbRepository _dbRepository = new FakeDbRepository();

        // Initialize Business object
        IProductBusiness productBusiness = new ProductBusiness(_dbRepository);

        // Process test method
        productBusiness.InsertForNewCategory("Test Product", "Test Category");

        int _productCount = _dbRepository.GetAll<Product>().Count();
        int _categoryCount = _dbRepository.GetAll<Category>().Count();

        Assert.AreEqual<int>(1, _productCount);
        Assert.AreEqual<int>(1, _categoryCount);
    }

    [TestMethod]
    public void TestProceduresFunctionsCall()
    {
        // Initialize Procedures / Functions result
        Hashtable _contextFunctionsResults = new Hashtable();
        _contextFunctionsResults.Add("GetProductsCategory", new List<GetProductsCategory_Result> { 
            new GetProductsCategory_Result() { ProductName = "Product 1", ProductID = 1, CategoryName = "Category 1" },
            new GetProductsCategory_Result() { ProductName = "Product 2", ProductID = 2, CategoryName = "Category 1" },
            new GetProductsCategory_Result() { ProductName = "Product 3", ProductID = 3, CategoryName = "Category 1" }});

        // Initialize repositories
        FakeDbRepository _dbRepository = new FakeDbRepository(_contextFunctionsResults);

        // Initialize Business object
        IProductBusiness productBusiness = new ProductBusiness(_dbRepository);

        // Process test method
        var results = productBusiness.GetProductsCategory(1);

        Assert.AreEqual<int>(3, results.Count());
    }
}