Full-host tests passed in isolation but failed 2-4/run under parallel execution on
Windows with 'the process cannot access the file ... because it is being used by
another process' (macOS never sees it — Unix deletes open files). Two shared-state
parallel collisions, discovered while verifying TST-08:
1. Self-signed cert generation. GatewayTlsBootstrapTests sets process-global
Kestrel/TLS env vars that GatewayApplication.Build reads; a parallel host-building
test inherits them mid-run and both generate a cert at the same path, racing on the
fixed-name '<path>.tmp'. Fixes:
- SelfSignedCertificateProvider: stage the PFX in a unique '<path>.<guid>.tmp' instead
of a fixed name, so concurrent/interrupted writers never collide on the temp file
(real robustness: two instances or a restart-during-write no longer clash). The
final atomic Move (last-writer-wins) still yields an equivalent cert.
- TestHostEnvironmentInitializer: default MxGateway__Tls__SelfSignedCertPath to a
per-process temp path so the suite never writes the shared ProgramData default or
fights the deployed service; first host-building test generates, the rest load it.
- GatewayTlsBootstrapTests: [Collection] with DisableParallelization so its global
env-var mutation cannot bleed into parallel tests (new GlobalEnvironmentCollection).
2. AuthStoreHealthCheckTests opened a real SQLite file; Microsoft.Data.Sqlite's
connection pool keeps the .db handle open after 'await using', so the finally
File.Delete threw. Reuse the existing TempDatabaseDirectory helper, which calls
SqliteConnection.ClearAllPools() before deleting.
Server build clean; affected classes 17/17 on macOS. Windows full-suite verified separately.
Joseph Doherty