Stabilize Mocha outbox registration test against EF provider warning

[glen-84]

Summary

• OutboxServiceRegistrationTests built its DbContext without suppressing EF Core's ManyServiceProvidersCreatedWarning, unlike the sibling integration test classes in the same assembly. EF Core escalates that warning to an exception once more than 20 internal service providers accumulate in its process-wide cache, so the test threw non-deterministically depending on test ordering and parallelism (it failed one CI run, then passed on re-run).
• Add .ConfigureWarnings(w => w.Ignore(CoreEventId.ManyServiceProvidersCreatedWarning)) to the test's AddDbContext call, matching the pattern already used by PostgresOutboxIntegrationTests and PostgresSchedulingIntegrationTests.

Test plan

• dotnet build src/Mocha/test/Mocha.EntityFrameworkCore.Postgres.Tests → 0 warnings, 0 errors
• dotnet test --filter-class ...OutboxServiceRegistrationTests → 4/4 passed

[Copilot]

Pull request overview

Stabilizes Mocha’s Postgres outbox service registration tests by aligning EF Core DbContext configuration with the existing integration tests to avoid nondeterministic failures caused by EF Core’s internal service provider cache warning being escalated to an exception.

Changes:

• Suppress EF Core ManyServiceProvidersCreatedWarning in OutboxServiceRegistrationTests by configuring EF warnings on the DbContext registration.
• Add the required EF Core diagnostics import to reference CoreEventId.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-code-quality]

Code Coverage Overview

Languages: C#

C# / code-coverage/dotnet

The overall coverage in the gai/stabilize-mocha-... branch remains at 49%, unchanged from the main branch.

Show a code coverage summary of the most impacted files.

File	main 3440480	gai/stabilize-mocha-... a5c69b2	+/-
/home/runner/wo...gerMessage.g.cs	19%	15%	-4%
/home/runner/wo...PromiseCache.cs	81%	78%	-3%
/home/runner/wo...geDispatcher.cs	77%	75%	-2%
/home/runner/wo...tocolHandler.cs	81%	82%	+1%
/home/runner/wo...DefaultTopic.cs	89%	90%	+1%
/home/runner/wo...tor/Mediator.cs	89%	91%	+2%
/home/runner/wo.../PingPongJob.cs	80%	83%	+3%
/home/runner/wo...entsListener.cs	62%	66%	+4%
/home/runner/wo...ewareFactory.cs	95%	100%	+5%
/home/runner/wo...gerMessage.g.cs	19%	28%	+9%

---

_{Updated June 17, 2026 10:58 UTC
Code Coverage is in Public Preview. Learn more and provide us with your feedback.}