C# 解耦EntityFramework进行单元测试

1. 首先ef的repository需要抽象的行为提到接口中。

例如 ：

public interface IXXXContext : IDisposable
    {
        IXXXContext NewInstance();
// db sets
        DbSet aaa { get; set; }
...
// common 
Database Database { get; }
        DbContextConfiguration Configuration { get; }
        int SaveChanges();


        Task SaveChangesAsync();


	// store pros
...
        IStorePro1 StorePro1 { get; }
	...
}

然后就可以使用DataContext和TestDataContext实现这个接口。其中TestDataContext是在UT中使用的，DataContext是自动生成的。

TestDataContext还需要以下几个类进行模拟。
 

 public class TestDbSet : DbSet, IQueryable, IEnumerable, IDbAsyncEnumerable
         where TEntity : class
    {
        ObservableCollection _data;
        IQueryable _query;


        public TestDbSet()
        {
            _data = new ObservableCollection();
            _query = _data.AsQueryable();
        }


        public override TEntity Add(TEntity item)
        {
            _data.Add(item);
            return item;
        }


        public override TEntity Remove(TEntity item)
        {
            _data.Remove(item);
            return item;
        }


        public override TEntity Attach(TEntity item)
        {
            _data.Add(item);
            return item;
        }


        public override TEntity Create()
        {
            return Activator.CreateInstance();
        }


        public override TDerivedEntity Create()
        {
            return Activator.CreateInstance();
        }


        public override ObservableCollection Local
        {
            get { return _data; }
        }


        Type IQueryable.ElementType
        {
            get { return _query.ElementType; }
        }


        Expression IQueryable.Expression
        {
            get { return _query.Expression; }
        }


        IQueryProvider IQueryable.Provider
        {
            get { return new TestDbAsyncQueryProvider(_query.Provider); }
        }


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


        IEnumerator IEnumerable.GetEnumerator()
        {
            return _data.GetEnumerator();
        }


        IDbAsyncEnumerator IDbAsyncEnumerable.GetAsyncEnumerator()
        {
            return new TestDbAsyncEnumerator(_data.GetEnumerator());
        }
    }


    internal class TestDbAsyncQueryProvider : IDbAsyncQueryProvider
    {
        private readonly IQueryProvider _inner;


        internal TestDbAsyncQueryProvider(IQueryProvider inner)
        {
            _inner = inner;
        }


        public IQueryable CreateQuery(Expression expression)
        {
            return new TestDbAsyncEnumerable(expression);
        }


        public IQueryable CreateQuery(Expression expression)
        {
            return new TestDbAsyncEnumerable(expression);
        }


        public object Execute(Expression expression)
        {
            return _inner.Execute(expression);
        }


        public TResult Execute(Expression expression)
        {
            return _inner.Execute(expression);
        }


        public Task