c# - 模拟 Entity Framework 长LINQ查询

有一个LINQ查询表达式（如下），该表达式要测试模拟实体框架。为了模拟，我使用代码：Entity Framework Testing with a Mocking Framework这适用于其他查询，但不适用于此var query = from vwPs in _reportingDbContext.VwAccountNumberjoin ps in _reportingDbContext.PaymentSummary on new { Key1 = vwPs.Id, Key2 = vwPs.AccountNumber, Key3 = true, Key4 = true } equals new { Key1 = ps.Id, Key2 = ps.AccountNumber, Key3 = ps.PaymentDate >= fromDateTime, Key4 = ps.PaymentDate < toDateTime } into viewJoinPaymentfrom ps in viewJoinPayment.DefaultIfEmpty()join prg in generatedReportIds on ps.PaymentRef equals prg into paymentJoinGeneratedfrom prgRow in paymentJoinGenerated.DefaultIfEmpty()where vwPs.Id == Idselect new{ vwPs.AccountNumber, Payments = ps, ReportGenerated = prgRow};执行查询时，此时代码中的“ _inner”中的值internal class TestDbAsyncEnumerator<T> : IDbAsyncEnumerator<T> { //... public Task<bool> MoveNextAsync(CancellationToken cancellationToken) { return Task.FromResult(_inner.MoveNext()); } //...}  ？ _内  {System.Linq.Enumerable.WhereSelectEnumerableIterator f__AnonymousType11 f__AnonymousType10 f__AnonymousType9 f__AnonymousType7>，LL.Core.DataAccess.Models.PaymentSummaryEntity>，System.Collections.Generic.IEnumerable>， > f__AnonymousType12>}      当前：null      结果视图：展开结果视图将枚举IEnumerable并且在执行MoveNext（）时获取异常  ？ _inner.MoveNext（）  '_inner.MoveNext（）'引发了类型'System.NullReferenceException'的异常      数据：{System.Collections.ListDictionaryInternal}      结果：-2147467261      帮助链接：null      InnerException：null      消息：“对象引用未设置为对象的实例。”      来源：“匿名托管的DynamicMethods程序集”      StackTrace：“位于lambda_method（Closure， f__AnonymousType9 2 )\r\n at System.Linq.Enumerable.<GroupJoinIterator>d__40 4.MoveNext（）\ r \ n位于      System.Linq.Enumerable.d__22 3.MoveNext()\r\n at System.Linq.Enumerable.WhereSelectEnumerableIterator 2.MoveNext（）“      TargetSite：{Int32 lambda_method（System.Runtime.CompilerServices.Closure，       f__AnonymousType9 2[<>f__AnonymousType7 2 [LL.Core.DataAccess.Models.VwAccountNumberEnt      ity，System.Collections.Generic.IEnumerable`1 [LL.Core.DataAccess.Models.PaymentSummaryEntity]] ,, LL.Core.DataAccess.Models.PaymentSummaryEntity]）}尝试了一些更改，包括此处建议的更改DbSet mock, no results while calling ToList secondly但仍然遇到相同的问题。拜托，有人可以给点儿光吗？不能选择使用集成测试来验证查询的实现，因为老板希望像其他所有查询一样在单元测试级别对此进行测试。更新：感谢@Eduard Malakhov，这是尝试过的方法。如果同时删除两个“ DefaultIfEmpty”并运行查询，则不会引发异常。但是如何避免DefaultIfEmpty的异常？我如何修改模拟代码以检查这种情况，因为未模拟调用不会发生异常？var query = from vwPs in _charityReportingDbContext.VwCharityAccountNumberjoin ps in _charityReportingDbContext.PaymentSummary on new { Key1 = vwPs.CharityId, Key2 = vwPs.AccountNumber, Key3 = true, Key4 = true } equals new { Key1 = ps.CharityId, Key2 = ps.AccountNumber, Key3 = ps.PaymentDate >= fromDateTime, Key4 = ps.PaymentDate < toDateTime } into viewJoinPaymentselect new{ vwPs.AccountNumber,}; (adsbygoogle = window.adsbygoogle || []).push({}); 最佳答案 我骇人听闻的“解决方案”（星期五，想回家:)。删除异常，但不幸的是，没有给出正确的结果。public Task<bool> MoveNextAsync(CancellationToken cancellationToken){try{ return Task.FromResult(_inner.MoveNext());}catch (Exception ex){ return Task.FromResult(false);}} (adsbygoogle = window.adsbygoogle || []).push({});