Remove file-based seeding for Cosmos DB functional tests

[JoasE]

File based seeding was very slow and used manual serialization. As far as I could see, it was only necessary for 1 test that could be rewritten. This approach, leveraging EF's batching SaveChangesAsync, is much faster. This is a remnant from: #37766 and is related to modernizing our serialization setup, removing the dependency on netwonsoft json. If file based seeding is still desired for some other reason, I will close this and publish a separate PR refactoring this to use STJ. Let me know which direction is wanted

[roji]

LGTM - I've never quite understand why we seed northwind from a file (including in relational).

But leaving to @AndriySvyryd to approve as he may have more context/insight.

[AndriySvyryd]

I've never quite understand why we seed northwind from a file (including in relational).

To test the query pipeline independently of the update pipeline

[roji]

So you think that's something we need to keep doing?

[AndriySvyryd]

So you think that's something we need to keep doing?

Not necessarily

[AndriySvyryd]

If the creation is fast now, we don't need to share and preserve the database. Let it uniquify it.

[JoasE]

to be clear: it's a lot faster, but still takes ~4 seconds. I've removed the _reservedNames and delete the database after each test now

[Copilot]

Pull request overview

This PR removes the legacy file-based Northwind seeding path used by EFCore.Cosmos functional tests, shifting seeding to the normal EF-based pipeline (batched SaveChangesAsync) to improve performance and reduce reliance on manual JSON serialization.

Changes:

• Removed file-based seeding support (and the associated Newtonsoft-based implementation) from CosmosTestStore.
• Deleted the specialized CosmosNorthwindTestStoreFactory and switched the Northwind Cosmos fixture to the standard CosmosTestStoreFactory.
• Updated the affected FromSql test and removed Northwind.json output-copy configuration from the test project.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/EFCore.Cosmos.FunctionalTests/TestUtilities/CosmosTestStore.cs	Removes file-based seeding path; introduces reserved-name handling adjustments.
test/EFCore.Cosmos.FunctionalTests/TestUtilities/CosmosNorthwindTestStoreFactory.cs	Deletes the Northwind-specific factory previously used for file seeding.
test/EFCore.Cosmos.FunctionalTests/Query/NorthwindQueryCosmosFixture.cs	Uses the default Cosmos test store factory rather than the deleted Northwind-specific one.
test/EFCore.Cosmos.FunctionalTests/Query/FromSqlQueryCosmosTest.cs	Adjusts the raw Cosmos SQL predicate/expected results to align with EF-seeded data shape.
test/EFCore.Cosmos.FunctionalTests/EFCore.Cosmos.FunctionalTests.csproj	Stops copying Northwind.json to output.

Comments suppressed due to low confidence (1)

test/EFCore.Cosmos.FunctionalTests/TestUtilities/CosmosTestStore.cs:485

• DisposeAsync now skips both RemoveShared and EnsureDeletedAsync for any store whose Name is in _reservedNames (Northwind/Northwind2/Northwind3). Previously, only the file-seeded store avoided deletion; with this change, the standard Northwind stores will no longer be cleaned up, which can leak Cosmos databases/containers (especially when running against a real Cosmos account) and can leave stale data between runs. Consider restoring deletion/removal for Northwind/Northwind2 (or restricting the non-deletion behavior to the one store that truly needs to persist) so that reserved naming doesn’t implicitly mean “never delete.”

    public override async ValueTask DisposeAsync()
    {
        if (_initialized
            && !_reservedNames.Contains(Name))
        {
            if (_connectionAvailable == false)
            {
                return;
            }

            if (Shared)
            {
                GetTestStoreIndex(ServiceProvider).RemoveShared(GetType().Name + Name);
            }

            await EnsureDeletedAsync(_storeContext).ConfigureAwait(false);

[JoasE]

To test the query pipeline independently of the update pipeline

@AndriySvyryd That is a good point! But from the context I gather that you don't think it's needed anymore. I could spend some timer refactor/improve/speed up the file based seeding via a CosmosClient aswell if you think it's worth it let me know. Otherwise you can go ahead and merge this

[AndriySvyryd]

Thanks for your contribution!