.Net 单元测试编译错误 - 类型或方法有 2 个通用参数，但提供了 1 个通用参数

Question

我们有一个泛型类，它包含一个使用外部类的泛型类型参数的私有(private)类。例子:

public class Foo<T>
{
  private class Bar : IGrouping<Guid,T>{


  }
}

问题是我们在一个单元测试项目中得到一个编译错误，它指出

"The Type or method has 2 generic parameter(s), but 1 generic argument(s) were provided. A generic argument must be provided for each generic parameter."

我提高了 MSBuild 的详细程度(工具 > 选项 > 项目和解决方案 > 构建和运行)。查看错误位置，它指向 Microsoft.TeamTest.targets 文件。我能够将其缩小到上面的这个类结构。如果我用类定义中的具体泛型参数替换私有(private)类 Bar(见下文)，则单元测试编译得很好:

private class Bar : IGrouping<Guid,int>{

}

我需要提供第二个泛型参数 generic 来接受外部类中的任何类型。对这个有想法吗？

为了澄清，编译错误在单元测试项目中，而不是上面列出的代码(编译得很好)。也许私有(private)访问器生成在 MS 单元测试基础架构中令人窒息？

这是[几乎]整个实际代码:

public class CategoryStorageService<T> : StorageServiceBase<T>, ICategoryStorageService<T> where T : IStorageContent, new()
{
    /// <summary>
    /// Returns a nested object graph of category-items
    /// </summary>
    /// <param name="categories"></param>
    /// <returns></returns>
    public IEnumerable<IGrouping<StorageCategory, T>> GetContent(params StorageCategory[] categories)
    {
        var results = this.GetContent(categories.Select(c => c.ID).ToArray());
        foreach (var result in results)
        {
            yield return new LocalNameGrouping(
                categories.First(c => c.ID == result.Key.ID),
                result);
        }
    }

    /// <summary>
    /// Returns a nested object graph of categories, each containing their items
    /// </summary>
    /// <param name="categories">The ID(s) of the category(ies) to fetch</param>
    /// <returns></returns>
    private IEnumerable<IGrouping<StorageCategory, T>> GetContent(params Guid[] categories)
    {

        // implementation removed

        return null;
    }      

    private class LocalNameGrouping : IGrouping<StorageCategory, T>
    {
        private IEnumerable<T> items;
        private StorageCategory category;

        public LocalNameGrouping(StorageCategory localCategory, IGrouping<StorageCategory, T> items)
        {
            this.items = items;
            string name = string.IsNullOrEmpty(localCategory.DisplayName) ? items.Key.DisplayName : localCategory.DisplayName;
            this.category = new StorageCategory { DisplayName = name, ID = items.Key.ID };
        }

        #region IGrouping<StorageCategory,T> Members

        public StorageCategory Key
        {
            get { return category; }
        }

        #endregion

        #region IEnumerable<T> Members

        public IEnumerator<T> GetEnumerator()
        {
            return items.GetEnumerator();
        }

        #endregion

        #region IEnumerable Members

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        {
            return this.GetEnumerator();
        }

        #endregion
    }

Answer 1

因此，私有(private)访问器处理对部分构造了泛型类定义的类型感到愤怒。例如，如果类声明如下:

private class LocalNameGrouping : IGrouping<StorageCategory, T> { 

}

然而，它对此很满意，仍然满足了需求(尽管有点俗气):

private class LocalNameGrouping<K> : IGrouping<K, T> where K: StorageCategory, new()
{

}