Implement unit tests for Test2::Harness infrastructure (27 files)

[Koan-Bot]

Context

The t/unit/Test2/Harness/ directory contains 27 test stubs for the inter-process infrastructure — collectors, IPC protocols, schedulers, preloading, reloading, resource management, and plugins. These form the plumbing of yath 2.0's distributed test execution.

Modules to test

Collector (9 files):

• Collector.t, Collector/Auditor.t, Collector/Auditor/Job.t, Collector/Auditor/Run.t, Collector/Child.t, Collector/IOParser.t, Collector/IOParser/Stream.t, Collector/Preloaded.t, Collector/TapParser.t

IPC (8 files):

• IPC/Connection.t, IPC/Protocol.t, IPC/Util.t
• IPC/Protocol/AtomicPipe.t, IPC/Protocol/AtomicPipe/Connection.t
• IPC/Protocol/IPSocket.t, IPC/Protocol/IPSocket/Connection.t
• IPC/Protocol/UnixSocket.t, IPC/Protocol/UnixSocket/Connection.t

Scheduler (2 files):

• Scheduler.t, Scheduler/Run.t

Other infrastructure (8 files):

• Plugin.t, Preload/Stage.t, Reloader.t, Reloader/Inotify2.t, Reloader/Stat.t, Resource.t, Resource/JobCount.t

Suggested test scenarios

Collector

• Collector.pm: finish() completion, event generation from test output
• Auditor: test result auditing — pass/fail/skip/todo counting, subtest tracking
• Auditor::Job: per-job auditing, BAIL_OUT handling
• Auditor::Run: run-level auditing, aggregation
• IOParser/Stream: streaming event parsing from test process stdout
• TapParser: TAP protocol parsing, plan detection, diagnostic handling
• Child: child process collector lifecycle
• Preloaded: preloaded test collection mode

IPC protocols

• Protocol base: start() / connect(), send_message() / get_message(), send_response() / get_request(), active() / health_check(), refuse_new_connections()
• AtomicPipe: file-based atomic pipe communication
• IPSocket: TCP socket IPC
• UnixSocket: Unix domain socket IPC
• Connection classes: per-connection state, message framing, reconnection

Scheduler

• start(ipcs) — scheduling initialization
• advance() — next-batch processing, job ordering by duration/priority
• terminate(reason) — graceful shutdown
• overall_status() / process_list() — status reporting
• Run management: add/remove runs, job state transitions
• abort() — marks runs halted, kills job PIDs

Other

• Plugin base: plugin interface contract
• Preload::Stage: preload stage definition and module grouping
• Reloader: file change detection and module reloading
• Reloader::Stat: stat-based change detection (polling)
• Reloader::Inotify2: inotify-based change detection (Linux)
• Resource/JobCount: job slot counting and allocation

Notes

IPC tests should cover all three transport protocols. Use AtomicPipe for CI-friendly tests (no port allocation needed). Test message ordering, concurrent sends, and connection failure recovery.

The Scheduler has known complexity around abort/halt handling — see abort_on_bail flag on runs. Test the BAIL_OUT → halt → abort cascade.

[atoomic]

@Koan-Bot fix