MockQueryable.NSubstitute 8.0.0 Breaks .AsQueryable() calls on DbSet<TEntity>

[ristogod]

This test code here works fine in version 7.0.4-beta.

using Microsoft.EntityFrameworkCore;
using MockQueryable.NSubstitute;

namespace AsQueryableTest;

public class UnitTest1
{
    [Fact]
    public async Task Test1()
    {
        List<Item> items =
        [
            new () { Id = 1 },
            new () { Id = 2 },
            new () { Id = 3 }
        ];

        var itemDbSet = items.BuildMockDbSet();

        var result = await itemDbSet.AsQueryable()
                                    .Where(static item => item.Id == 1)
                                    .CountAsync();

        Assert.Equal(1, result);
    }

    public class Item
    {
        public int Id { get; set; }
    }
}

However, in version 8.0.0, we get this exception:

System.InvalidOperationException
The provider for the source 'IQueryable' doesn't implement 'IAsyncQueryProvider'. Only providers that implement 'IAsyncQueryProvider' can be used for Entity Framework asynchronous operations.
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ExecuteAsync[TSource,TResult](MethodInfo operatorMethodInfo, IQueryable`1 source, Expression expression, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ExecuteAsync[TSource,TResult](MethodInfo operatorMethodInfo, IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.CountAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at AsQueryableTest.UnitTest1.Test1() in ...AsQueryableTest\AsQueryableTestError\UnitTest1.cs:line 20
   at Xunit.Sdk.TestInvoker`1.<>c__DisplayClass47_0.<<InvokeTestMethodAsync>b__1>d.MoveNext() in /_/src/xunit.execution/Sdk/Frameworks/Runners/TestInvoker.cs:line 259
--- End of stack trace from previous location ---
   at Xunit.Sdk.ExecutionTimer.AggregateAsync(Func`1 asyncAction) in /_/src/xunit.execution/Sdk/Frameworks/ExecutionTimer.cs:line 48
   at Xunit.Sdk.ExceptionAggregator.RunAsync(Func`1 code) in /_/src/xunit.core/Sdk/ExceptionAggregator.cs:line 90

Yes, if I remove the .AsQueryable() it works. However, we have production code that makes use of .AsQueryable() from our DbContext.DbSet implementations because there might be ambiguity issues between IQueryable and IEnumerable extensions.

I wasn't sure if I was going to submit this, so I asked fellow developers their opinions and this was some of their thoughts:

"A likely cause is that in 7.0.4-beta, .AsQueryable() returned an instance of TestAsyncEnumerableEfCore, which implements IAsyncQueryProvider. In version 8.0.0, .AsQueryable() no longer returns this type, which results in the loss of IAsyncQueryProvider support.

Since a real DbSet supports AsQueryable() and the purpose of BuildMockDbSet is to mimic DbSet behavior, this is a regression from 7.0.4-beta. So I think this is a bug rather than an intentional design change."

[romantitov]

Fixed in v8.0.1