[APPS-2792] Add: local-execution resilience tests

[tyffical]

Motivation

• Local-execution resilience testing milestone from the Local Node Execution Kickoff doc.
  • Renamed/descoped from "Chaos-engineering resilience testing" since domains/chaos-engineering targets Datadog-owned Kubernetes clusters — a mismatch for this in-process, customer-dev-server model.
• Two targeted checks, not fixes:
  • Empirically confirm the RFC's "no process isolation" decision has the failure modes it assumes, rather than leave them unverified.

Architecture

• The process.exit() test can't call runScriptLocally directly in the main Jest process — exiting would kill the whole test run.
• It spawns the fixture as a child process instead, and asserts on the child's exit behavior:

Jest test process
  └─ spawns ──▶ local-execution.process-exit.fixture.ts (child process)
                  runScriptLocally() → customer fn calls process.exit()
                  → child terminates immediately
  └─ asserts on the child's exit code

Changes

4 changes across 5 files

What changed	File
New test confirming a synchronous CPU-bound loop starves the event loop, so the current Promise.race timeout never fires — it can only settle once the loop finishes on its own.	local-execution.resilience.test.ts
New test confirming process.exit() inside the customer function terminates the whole process immediately, bypassing runScriptLocally's try/finally cleanup — spawns a dedicated fixture as its own Jest process (since process.exit() can't safely run inside this Jest process) so the observed behavior is the real executeScriptLocally/runScriptLocally code path, not a hand-rolled emulation of it.	local-execution.resilience.test.ts, local-execution.process-exit.fixture.ts
The spawned fixture's --globalSetup is overridden to a new no-op, since it doesn't touch the fixtures directory and doesn't need the real globalSetup.ts's yarn install + git init/config cost.	noopGlobalSetup.ts, local-execution.resilience.test.ts
Extracted the identical func/stubExecuteAction fixture data — previously declared separately in this file, the resilience test, and the spawned fixture — into a new shared module, since the fixture already proves shared imports work fine in its spawned process (it already imports mockLogger/moduleResolverFor from a shared helpers module).	local-execution.fixtures.ts, local-execution.test.ts, local-execution.resilience.test.ts, local-execution.process-exit.fixture.ts

• The third checklist item ("the queue survives a rejected execution and keeps running") is already covered by an existing test in local-execution.test.ts.

QA Instructions

• Test-only change with no HTTP surface — verified via the unit test commands below, not a live endpoint.

yarn workspace @dd/tests test:unit packages/plugins/apps/src/vite/local-execution.resilience.test.ts
# Expected: 2 passed ✅ VERIFIED

yarn build:all && yarn test:unit
# Full, unscoped suite — a scoped run can't catch a process-wide guard leaking into
# an unrelated package's tests via a shared Jest worker (see the Confluence QA guide).
# Expected: Test Suites: 89 passed / Tests: 2152 passed, 1 skipped ✅ VERIFIED

yarn workspace @dd/apps-plugin run typecheck
# Expected: clean exit ✅ VERIFIED

Blast Radius

• Test-only change; no production code touched.
• Risk: low.

Out of Scope / Follow-ups

1 item deferred

Item	Status	Next step
Whether to pursue real process/thread isolation (e.g. pooled worker_threads) to close the confirmed sync-hang and process.exit() gaps	deferred	These tests exist to inform that decision with real data — a follow-up design discussion, not blocking this PR.

Documentation

• RFC: Local Node execution for High Code Apps backend functions — "Run in-process instead of forking an isolated child process" trade-off this milestone verifies.
• QA guide: Confluence page 7100498075 — exact local/staging QA commands for this repo.

[datadog-datadog-prod-us1]

✅ All CI checks and tests passed.

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 9d778b3 | Docs | View more details | Give us feedback!}

[tyffical]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-02T22:58:35.639644Z	3b7dbea	Manual request

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[Copilot]

🟡 Changes recommended

The process-exit test relies on Jest-buffered output that may be lost during immediate termination.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Friend, this PR adds resilience tests documenting known limitations of in-process local execution.

Changes:

• Tests CPU-bound timeout starvation and process.exit() behavior.
• Adds a child-process Jest fixture.
• Extracts shared local-execution fixtures.

File summaries

File	Description
local-execution.test.ts	Reuses shared fixtures and strengthens cleanup.
local-execution.resilience.test.ts	Adds resilience tests.
local-execution.process-exit.fixture.ts	Exercises process termination safely.
local-execution.fixtures.ts	Centralizes test data.

Review details

Suppressed comments (1)

packages/plugins/apps/src/vite/local-execution.process-exit.fixture.ts:24

• The inline resolver construction hides fixture setup inside the execution under test. Create a named resolver first and pass it to executeScriptLocally so setup and execution remain separate.

        moduleResolverFor(func, {

• Files reviewed: 4/4 changed files
• Comments generated: 3
• Review effort level: Balanced

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 🚀

Reviewed commit: 3b7dbea94d

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• Mark a draft as ready
• Comment "@codex review".

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