如何通过 Wrapper 模拟上下文

Question

我有一种情况是通过包装器使用上下文。包装器用于服务层。问题是在这种情况下如何模拟上下文？

上下文

public class DbContext : System.Data.Entity.DbContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        ...

        base.OnModelCreating(modelBuilder);
    }

    public DbSet<Report> Reports { get; set; }
}

包装器

public interface IDbContextWrapper<out TContext> where TContext : System.Data.Entity.DbContext, new()
{
    T Call<T>(Func<TContext, T> func);

    void Call(Action<TContext> action);
}

包装器实现

public class DbContextWrapper<TContext> : IDbContextWrapper<TContext> where TContext : System.Data.Entity.DbContext, new()
{

    public virtual TContext BuildContext(bool enableChangeTracking = true, bool enableLazyLoading = false, bool enableProxyCreation = false)
    {
        var result = new TContext();
        result.Configuration.AutoDetectChangesEnabled = enableChangeTracking;
        result.Configuration.LazyLoadingEnabled = enableLazyLoading;
        result.Configuration.ProxyCreationEnabled = enableProxyCreation;
        return result;
    }

    public virtual T Call<T>(Func<TContext, T> func)
    {
        using (var context = BuildContext())
        {
            return func(context);
        }
    }

    public virtual void Call(Action<TContext> action)
    {
        using (var context = BuildContext())
        {
            action(context);
        }
    }
}

以及我需要使用 Mocks 进行单元测试的服务及其方法

public class ReportService : IReportService
{
    private readonly IDbContextWrapper<DbContext> _contextWrapper;

    public ReportService(IDbContextWrapper<DbContext> contextWrapper)
    {
        _contextWrapper = contextWrapper;
    }


    public Report GetPreviousReport(int currentReportId, int lineId)
    {
        return _contextWrapper.Call(
            context => context.Reports
                .Where(item => item.Id < currentReportId && item.LineId == lineId)
                .OrderBy(item => item.Id)
                .First());
    }

    public Report GetNextReport(int currentReportId, int lineId)
    {
        return _contextWrapper.Call(
            context => context.Reports
                .Where(item => item.Id > currentReportId && item.LineId == lineId)
                .OrderBy(item => item.Id)
                .First());
    }
}

Answer 1

在您的测试中，您可以创建 StubTContext 并将报告初始化为 return 测试数据。然后用 IDbContextWrapper 初始化您的被测系统 ReportService。

完成此准备后，使用 Moq 模拟 IDbContextWrapper，如下所示：

Mock<IDbContextWrapper<StubTContext>> mock = new Mock<IDbContextWrapper<StubTContext>>();

mock.Setup(m => m.Call(It.IsAny<Action<StubTContext>>())).Callback<Action<StubTContext>>(a => a.Invoke(new StubTContext()));

您还可以实现 StubTContext 以通过构造函数提供测试数据，然后仅在模型期间将测试数据传递给它。像这样：

public StubTContext : DbContext
{
   public StubTContex(DbSet<Report> reports)
   {
       Reports = reports;
   }
}

然后在模拟中

mock.Setup(m => m.Call(It.IsAny<Action<StubTContex>>())).Callback<Action<StubTContex>>(a => a.Invoke(new StubTContex(*YOUR REPORTS*)));

如何通过 Wrapper 模拟上下文

How to Mock Context through Wrapper

c#

unit-testing

mocking

wrapper

dbcontext