Integration test suite: ThreadPoolExecutor through TraverseRuntime (spec 047)

[enricopiovesan]

Summary

Write integration tests that wire `ThreadPoolExecutor` through the full `TraverseRuntime` stack — registry, router, placement, trace — and verify end-to-end correctness under concurrent load. These tests live in `crates/traverse-runtime/tests/thread_pool_integration.rs`.

Governing Spec

• `047-thread-pool-executor`

Blocked by

• Unit test suite: ThreadPoolExecutor (spec 047) #506 (unit tests must pass before integration layer is tested)

Test inventory

Drop-in replacement

Test name	What it proves
`native_executor_and_thread_pool_produce_identical_output`	Same capability, same input — `NativeExecutor` and `ThreadPoolExecutor` return byte-identical `Value` output
`thread_pool_executor_satisfies_capability_executor_trait_object`	`Box` can hold a `ThreadPoolExecutor` — compiles and executes

Router integration

Test name	What it proves
`router_routes_to_thread_pool_executor`	A capability registered with `ArtifactType::Native` and resolved through the placement router executes correctly via pool
`router_concurrent_requests_to_same_capability`	8 concurrent `execute_capability()` calls through the router — all return correct results, no deadlock
`router_concurrent_requests_to_different_capabilities`	4 concurrent calls to 4 distinct capabilities — each receives its own correct output

Trace correctness

Test name	What it proves
`concurrent_executions_produce_isolated_traces`	4 concurrent executions produce 4 distinct trace entries — no cross-contamination in `TraceStore`
`trace_capability_id_matches_executed_capability`	Trace entry `capability_id` matches the dispatched capability for each concurrent call
`failed_execution_recorded_in_trace`	A capability that returns `ExecutorError` produces a trace entry with failure status

Event broker integration

Test name	What it proves
`event_published_by_pool_thread_reaches_broker`	A capability executing on a pool thread can publish an event; the broker records it
`concurrent_event_publishers_no_broker_corruption`	4 capabilities each publishing 3 events concurrently — broker contains all 12, no duplicates, no data races

Workflow traversal

Test name	What it proves
`workflow_with_thread_pool_executor_completes_all_steps`	A 3-step workflow using `ThreadPoolExecutor` for native capabilities completes with correct final output
`workflow_step_failure_halts_traversal`	A workflow step returning error halts traversal at that step — subsequent steps not executed

WASM path unchanged

Test name	What it proves
`wasm_capability_bypasses_thread_pool`	A WASM capability registered alongside native capabilities executes via `WasmExecutor` — `ThreadPoolExecutor` is not invoked for it

Definition of Done

• All 13 tests above exist in `crates/traverse-runtime/tests/thread_pool_integration.rs`
• All tests pass with `cargo test -p traverse-runtime --test thread_pool_integration`
• No test uses `unwrap()` or `expect()` in assertion paths
• Concurrent tests use `std::thread::scope` or equivalent — no `unsafe` thread spawning
• Trace correctness tests inspect `TraceStore` contents directly after execution
• WASM path test uses the expedition example WASM binary from `examples/expedition/`
• `bash scripts/ci/spec_alignment_check.sh` passes
• PR body declares ````047-thread-pool-executor```` in `## Governing Spec`