Fix UserStoreTest

[MackinnonBuck]

No description provided.

[MackinnonBuck]

Worked once, but this is a flaky test. Re-running to validate that this is really fixed.

[MackinnonBuck]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[BrennanConroy]

Worked once, but this is a flaky test. Re-running to validate that this is really fixed.

Is it flaky locally? Try adding [Repeat(1000)] to the test and seeing if it fails.

[MackinnonBuck]

Worked once, but this is a flaky test. Re-running to validate that this is really fixed.

Is it flaky locally? Try adding [Repeat(1000)] to the test and seeing if it fails.

I haven't been able to reproduce the failure consistently locally, even with "Run until failure". I think I've only seen it fail locally one time.

[Copilot]

Pull Request Overview

This PR fixes the UserStoreTest class by introducing a dedicated test-specific DbContext class to replace direct usage of the generic IdentityDbContext. The changes ensure proper type safety and consistency throughout the test suite.

• Introduces UserStoreTestDbContext as a dedicated test context class
• Replaces all IdentityDbContext references with the new UserStoreTestDbContext
• Updates method signatures and generic type parameters consistently

[MackinnonBuck]

I believe the culprit was that EF Core caches compiled models per DbContext type. Multiple test classes were using the base IdentityDbContext type with different IdentitySchemaVersions configurations (including UserStoreTest). When tests ran in parallel, the first test would cache a model with its schema version, and subsequent tests would reuse that model regardless of their configuration. If a test with the default schema (Version1, no passkey support) ran first, later tests expecting Version3 would fail. I fixed this by using a UserStoreTestDbContext type instead of the shared IdentityDbContext, which matches the pattern already used by some of the other test files.

[ilonatommy]

Is it ready? Before I noticed this fix attempt, I opened #64056, #64055 to quarantine them because they blocks the pipeline.

[MackinnonBuck]

@ilonatommy this PR is ready. Just needs an approval.