fix(testing): add retry logic for testing token fetch on 429/5xx

[jacekradko]

Summary

• Adds retry with exponential backoff to the testing token fetch in @clerk/testing
• Retries up to 5 times on transient HTTP errors (408, 429, 500, 502, 503, 504) with exponential backoff + jitter
• Retries on network-level errors (ECONNREFUSED, ECONNRESET, ENOTFOUND, ETIMEDOUT, EAI_AGAIN)
• Respects Retry-After headers when provided, with all delays capped at 30s
• Retry attempts emit warning logs with status/error code, attempt count, and wait time
• Adds unit tests for the retry logic covering all retry/non-retry paths

Why

fetchEnvVars calls testingTokens.createTestingToken() without retry handling, causing E2E test failures when FAPI returns 429 (Too Many Requests) under concurrent test workers or when transient network issues occur against staging.

Test plan

• @clerk/testing builds successfully
• 19 unit tests covering retryable HTTP statuses, network errors, max retries, retryAfter handling, non-retryable errors, and existing token bypass
• Run E2E tests with concurrent workers to confirm 429s are retried instead of failing immediately

[changeset-bot]

🦋 Changeset detected

Latest commit: e27ba1a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@clerk/testing	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
clerk-js-sandbox	Ready	Preview, Comment	Mar 31, 2026 0:39am

[pkg-pr-new]

Open in StackBlitz

@clerk/agent-toolkit

npm i https://pkg.pr.new/@clerk/agent-toolkit@8138

@clerk/astro

npm i https://pkg.pr.new/@clerk/astro@8138

@clerk/backend

npm i https://pkg.pr.new/@clerk/backend@8138

@clerk/chrome-extension

npm i https://pkg.pr.new/@clerk/chrome-extension@8138

@clerk/clerk-js

npm i https://pkg.pr.new/@clerk/clerk-js@8138

@clerk/dev-cli

npm i https://pkg.pr.new/@clerk/dev-cli@8138

@clerk/expo

npm i https://pkg.pr.new/@clerk/expo@8138

@clerk/expo-passkeys

npm i https://pkg.pr.new/@clerk/expo-passkeys@8138

@clerk/express

npm i https://pkg.pr.new/@clerk/express@8138

@clerk/fastify

npm i https://pkg.pr.new/@clerk/fastify@8138

@clerk/hono

npm i https://pkg.pr.new/@clerk/hono@8138

@clerk/localizations

npm i https://pkg.pr.new/@clerk/localizations@8138

@clerk/nextjs

npm i https://pkg.pr.new/@clerk/nextjs@8138

@clerk/nuxt

npm i https://pkg.pr.new/@clerk/nuxt@8138

@clerk/react

npm i https://pkg.pr.new/@clerk/react@8138

@clerk/react-router

npm i https://pkg.pr.new/@clerk/react-router@8138

@clerk/shared

npm i https://pkg.pr.new/@clerk/shared@8138

@clerk/tanstack-react-start

npm i https://pkg.pr.new/@clerk/tanstack-react-start@8138

@clerk/testing

npm i https://pkg.pr.new/@clerk/testing@8138

@clerk/ui

npm i https://pkg.pr.new/@clerk/ui@8138

@clerk/upgrade

npm i https://pkg.pr.new/@clerk/upgrade@8138

@clerk/vue

npm i https://pkg.pr.new/@clerk/vue@8138

commit: e27ba1a

[coderabbitai]

Note

Reviews paused

It looks like this branch is under active development. To avoid overwhelming you with review comments due to an influx of new commits, CodeRabbit has automatically paused this review. You can configure this behavior by changing the reviews.auto_review.auto_pause_after_reviewed_commits setting.

Use the following commands to manage reviews:

• @coderabbitai resume to resume automatic reviews.
• @coderabbitai review to trigger a single review.

Use the checkboxes below for quick actions:

• ▶️ Resume reviews
• 🔍 Trigger review

📝 Walkthrough

Walkthrough

Added a generic fetchWithRetry(fn, label) wrapper and an isClerkAPIResponseError type guard. fetchWithRetry retries failed async operations up to MAX_RETRIES + 1 attempts when the error is a Clerk API response with status in {408, 429, 500, 502, 503, 504} or a network-like error with code in {ECONNREFUSED, ECONNRESET, ENOTFOUND, ETIMEDOUT, EAI_AGAIN}. Retry delay uses error.retryAfter (seconds→ms, capped) for Clerk errors or exponential backoff with jitter (capped) otherwise. Each retry logs a console.warn; non-retryable errors or exhausted attempts rethrow the error.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: adding retry logic for testing token fetch on 429/5xx errors. It directly matches the changeset's primary objective.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/testing/src/common/setup.ts`:
- Around line 8-45: Add unit tests for fetchWithRetry and isNetworkError: write
tests that assert isNetworkError returns true for errors with codes in
RETRYABLE_NETWORK_ERRORS and false otherwise; for fetchWithRetry, mock fn to
throw retryable API errors (status in RETRYABLE_STATUS_CODES) and network errors
to verify retries occur up to MAX_RETRIES and that the final error is thrown
when exhausted, verify that when an API error includes retryAfter (seconds) the
delay uses Math.min(retryAfter*1000, MAX_RETRY_DELAY_MS), and assert
non-retryable errors are rethrown immediately; also include a test to ensure
backoff increases (exponential + jitter) and that the console.warn message
includes the label and attempt info. Use mocks/timers to control setTimeout and
deterministic delays.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository YAML (base), Organization UI (inherited)

Review profile: ASSERTIVE

Plan: Pro

Run ID: 3001f82a-b12a-46fa-b95b-76b3b0471f86

📥 Commits

Reviewing files that changed from the base of the PR and between 058d27f and 4cf7693.

📒 Files selected for processing (1)

• packages/testing/src/common/setup.ts