EntityFramework Core 6 upgrade Could not load type IAsyncQueryProvider

Question

I've updated my .NET Core 3.1 application to .NET 6 and one step was to also update EntityFramwork Core to version 6.0.2.

Unfortunately, many of my unit tests are now failing with the exception:

System.TypeLoadException: Could not load type 'Microsoft.EntityFrameworkCore.Query.Internal.IAsyncQueryProvider' from assembly 'Microsoft.EntityFrameworkCore, Version=6.0.2.0,

I'm not really sure why this is happening. I've gone through the migration guide (https://docs.microsoft.com/en-us/aspnet/core/migration/31-to-60?view=aspnetcore-6.0&tabs=visual-studio) and haven't seen anything like this mentioned.

Here is one example of a unit test that fails with this exception:

[TestMethod]
public async Task IsPrivatKundeAsync_WithMatchingCriteria_ReturnsTrue()
{
    var data = new[] {
        new MyEntity { Partnernr = "1", Geburtstag = new DateTime(2000, 1, 1), Plz = "8000" },
        new MyEntity { Partnernr = "2", Geburtstag = new DateTime(2001, 2, 2), Plz = "8001" },
        new MyEntity { Partnernr = "3", Geburtstag = new DateTime(2002, 3, 3), Plz = "8002" },
    };

    var builder = new DbContextOptionsBuilder<MyDbContext>().UseInMemoryDatabase(Guid.NewGuid().ToString());
    var db = new Mock<MyDbContext>(builder.Options);
    db.Setup(x => x.MyEntity).Returns(data.AsQueryable().BuildMockDbSet().Object);

    IPartner partner = new Partner(db.Object);
    var result = await partner.IsPrivatKundeAsync(data[1].Partnernr, data[1].Geburtstag.Value, data[1].Plz);

    Assert.IsTrue(result);
}

These tests have been working before the update.

Thanks for any insights :-)

Answer 1

The issue most likely is in one of the packages that you use for testing.

EF Core changed the namespace of this class from Microsoft.EntityFrameworkCore.Query.Internal.IAsyncQueryProvider to Microsoft.EntityFrameworkCore.Query.IAsyncQueryProvider between ef core versions 3 to 5 and it means that one of the test packages either needs to be updated or changed. In my case it was MockQueryable.Moq package.