fix: attribute registration to the app, not the extension that registered for it (#601)

[jeremydmiller]

Fixes #601.

Stacked on #602. Both change the same walk, so this PR targets gh600/skip-test-runner-assemblies rather than main. Review #602 first; this diff is the second commit only. Retarget to main once #602 merges.

The defect

Follow-up to #600 — same function, different failure mode. Where #600 was about the walk landing on a test runner, this is about it landing on an intermediate Critter Stack assembly.

UseWolverine() and AddMarten() both call services.AddJasperFx() from inside their own assembly (Wolverine/HostBuilderExtensions.cs:109, Marten/MartenServiceCollectionExtensions.cs:210,331), so the first frame outside JasperFx belongs to the extension, not the application.

Reproduced, not taken on faith

The issue measured Wolverine's twin of this logic and noted JasperFx's own walk had not been instrumented directly. It has now. A stand-in extension assembly that calls AddJasperFx() on the app's behalf, in a real host:

RegistrationCallingAssembly = Wolverine.StackWalkStandIn   <- the extension
ApplicationAssembly         = CoreTests                    <- correct
Warning                     = FIRED                        <- on a host where nothing is wrong

That inverts the warning's whole value. It trains readers to ignore it, and its absence stops being evidence — on JasperFx/wolverine#3776, "zero occurrences of the warning in the failing logs" was explicitly recorded as grounds for ruling out an application-assembly problem, and that was exactly the bug.

It is more than warning noise

The same stack walk seeds the process-wide RememberedApplicationAssembly in AddJasperFx. Where IHostEnvironment.ApplicationName is empty, establishApplicationAssembly falls through to that pin — so the extension assembly became the assembly type discovery scans. Measured on a bare ServiceCollection:

RegistrationCallingAssembly=Widgets1 | Remembered=Widgets1 | ApplicationAssembly=Widgets1 | Warning=none

Note Warning=none there: registered and adopted agree, because both are wrong the same way. The divergence check is silent in exactly the case where it is most needed.

The fix

Skip Critter Stack framework assemblies in the walk, alongside the runners:

if (assemblyName.StartsWith("System") || assemblyName.StartsWith("Microsoft") ||
    IsTestRunnerAssembly(assemblyName) || IsCritterStackAssembly(assemblyName))
{
    continue;
}

Two guards against the risk the issue flags — "it must not skip a legitimate application assembly that happens to be named for a product":

1. Exact name or dotted prefix, never a bare StartsWith. Wolverine and Wolverine.SqlServer match; WolverineDemo, MartenPlayground and JasperFxSamples do not.
2. Never a *.Tests / *.Testing assembly. Wolverine.RabbitMQ.Tests and Marten.Testing ARE the application as far as discovery is concerned — their handlers and documents are the types under test. Skipping those would reintroduce DetermineCallingAssembly adopts the test-runner assembly, so type discovery scans a runner instead of the test assembly #600 from the other direction.

List: JasperFx · Wolverine · WolverineFx · Marten · Weasel · Polecat · CritterWatch · Oakton.

Tests

src/ExtensionStandIn is a project whose only purpose is its assembly name — Wolverine.StackWalkStandIn — with an extension method that calls AddJasperFx() on the caller's behalf. Same trick as TestRunnerStandIn in #602.

• registration_is_attributed_to_the_app_not_the_extension_that_registered_for_it — real host; asserts RegistrationCallingAssembly is the test assembly and that the divergence warning stays quiet.
• an_extension_registration_does_not_pin_the_extension_as_the_application_assembly — the no-ApplicationName path; asserts neither ApplicationAssembly nor the process-wide pin becomes the extension.
• Predicate theories covering the framework names, the look-alike application names, and the in-repo test suites.

Both behaviour tests fail without the fix and pass with it. Full CoreTests green (539 passed, 1 skipped).

Not done here

The issue's option 2 — capturing the registering assembly at the outermost public entry point instead of re-deriving it from a stack walk — is the structurally better answer and is unaffected by this change. This is the version that needs no downstream work in Wolverine or Marten to take effect.

🤖 Generated with Claude Code

[jeremydmiller]

Auto-closed by GitHub when its stacked base branch (gh600/skip-test-runner-assemblies) was deleted on merge of #602, and it will not reopen. Superseded by #606 — same branch, same commit, rebased onto main.