--- name: emulate-seed description: "Generate emulate seed configs for stateful API emulation. Wraps Vercel's emulate tool for GitHub, Vercel, Google OAuth, Slack, Apple Auth, Microsoft Entra, AWS (S3/SQS/IAM), Okta, Resend, Stripe, and MongoDB Atlas APIs. Not mocks — full state machines where create-a-PR-and-it-appears-in-the-list, send-an-email-and-retrieve-from-local-inbox. Use when setting up test environments, CI pipelines, integration tests, or offline development." tags: [emulate, testing, api-emulation, github, vercel, google, stripe, resend, okta, mongodb, seed, ci, stateful-testing] version: 1.2.0 author: OrchestKit user-invocable: false disable-model-invocation: false complexity: medium context: inherit persuasion-type: guidance agent: emulate-engineer metadata: category: testing upstream-package: emulate upstream-version-tested: "0.4.1" --- # Emulate Seed Configs Generate and manage seed configs for [emulate](https://github.com/vercel-labs/emulate) (Apache-2.0) — Vercel Labs' stateful API emulation tool. Each category has individual rule files in `rules/` loaded on-demand. > **Paired agent:** This skill pairs with the [`emulate-engineer`](../../agents/emulate-engineer.md) subagent (`subagent_type: "emulate-engineer"`). When a task involves generating a full emulate config from scratch, webhook HMAC setup, CI pipeline integration, or parallel-worker port isolation, spawn the agent rather than handling it inline — it has the full 12-emulator service-port matrix and seed-rules in context. **Not mocks.** Emulate provides full state machines with cascading deletes, cursor pagination, webhook delivery, and HMAC signature verification. Create a PR via the API and it appears in `GET /repos/:owner/:repo/pulls`. Delete a repo and its issues, PRs, and webhooks cascade-delete. ## New in 2026-04 (emulate 0.4.x) - **Modular `@emulators/*` packages** — each service is its own package (`@emulators/github`, `@emulators/stripe`, etc.); top-level `emulate` re-exports `createEmulator` and the CLI. - **4 new services** (12 total): `mongoatlas:4007`, `okta:4008`, `resend:4009`, `stripe:4010` with drop-in seed YAML blocks. - **Resend local inbox** — `GET http://localhost:4009/inbox` returns captured emails for assertions without hitting a real provider. - **Stripe hosted checkout** — real session redirect flow + `checkout.session.completed`/`expired` webhook delivery, suitable for E2E payment tests. - **MongoDB Atlas** — Admin API v2 (projects/clusters/DB users) + Data API v1 with full CRUD + aggregate. - **Okta OIDC** — full discovery, JWKS, `authorize/token/userinfo/revoke/introspect` plus Users/Groups/Apps CRUD. - **Entra / Apple / Slack expansions (v0.4.0)** — PKCE + refresh rotation (Entra), RS256 JWKS (Apple), OAuth v2 consent UI (Slack). - **`@emulators/adapter-next`** — catch-all Next.js route handler runs emulators on the same origin as the app; fixes OAuth callback URL drift on Vercel preview deploys. ## Quick Reference | Category | Rules | Impact | When to Use | |----------|-------|--------|-------------| | [Seed Config](#seed-config) | 1 | HIGH | Setting up emulate.config.yaml for test environments | | [Service Selection](#service-selection) | 1 | MEDIUM | Choosing GitHub/Vercel/Google for your tests | | [Webhook Setup](#webhook-setup) | 1 | MEDIUM | Testing webhook delivery with HMAC verification | | [Parallel CI](#parallel-ci) | 1 | HIGH | Running tests in parallel without port collisions | | [Auth Tokens](#auth-tokens) | 1 | MEDIUM | Seeding tokens mapped to emulated users | **Total: 5 rules across 5 categories** ## Quick Start ```bash # Install (packages published under @emulators/* scope) npm install --save-dev emulate # Start all services npx emulate # Start specific services with seed data npx emulate --service github,stripe --seed ./emulate.config.yaml # Generate a starter config npx emulate init --service github ``` ## Services (0.4.1 — 12 emulators) | Service | Default Port | Coverage | |---------|-------------|----------| | **Vercel** | `:4000` | Projects, deployments, domains, env vars, teams | | **GitHub** | `:4001` | Repos, PRs, issues, comments, reviews, Actions, webhooks, orgs, teams | | **Google OAuth** | `:4002` | OAuth 2.0 authorize, token exchange, userinfo | | **Slack** | `:4003` | Chat, conversations, users, reactions, OAuth v2 with consent UI | | **Apple Auth** | `:4004` | Sign in with Apple — OIDC discovery, JWKS (RS256), auth flow, token exchange | | **Microsoft Entra** | `:4005` | OAuth 2.0/OIDC v2.0, authorization code + PKCE, refresh token rotation, v1 token endpoint, Graph `/users/{id}` | | **AWS** | `:4006` | S3 buckets, SQS queues, IAM users/roles, STS identity | | **MongoDB Atlas** *(0.4+)* | `:4007` | Admin API v2 (projects, clusters, DB users) + Data API v1 (full CRUD + aggregate) | | **Okta** *(0.4+)* | `:4008` | OIDC discovery, JWKS, authorize/token/userinfo/revoke/introspect, Users/Groups/Apps CRUD | | **Resend** *(0.4+)* | `:4009` | Send + batch (100/req), list/retrieve/cancel, domains, API keys, audiences, contacts, **local inbox** (`GET /inbox`) | | **Stripe** *(0.4+)* | `:4010` | Customers, payment methods, customer sessions, payment intents, charges, products, prices, **hosted checkout session** w/ webhook delivery | | **Clerk** | (on-demand) | Users, sessions, organizations | See `references/api-coverage.md` for full endpoint lists. ### Next.js Adapter (0.4+) — `@emulators/adapter-next` Runs emulators **on the same origin** as your Next.js app via a catch-all route handler. Fixes the OAuth callback URL drift problem on Vercel preview deploys — no more `http://localhost:4001` redirect mismatches. ```typescript // next.config.js const { withEmulate } = require('@emulators/adapter-next') module.exports = withEmulate({ /* your next config */ }) // app/api/[...emulate]/route.ts import { createEmulateHandler } from '@emulators/adapter-next' export const { GET, POST } = createEmulateHandler({ services: ['github', 'stripe', 'resend'], persistence: { /* load(), save() or built-in filePersistence */ }, }) ``` ## Seed Config Structure A seed config pre-populates the emulator with tokens, users, repos, and projects so tests start from a known state. ```yaml # emulate.config.yaml tokens: dev_token: login: yonatangross scopes: [repo, workflow, admin:org] ci_token: login: ci-bot scopes: [repo] github: users: - login: yonatangross name: Yonatan Gross - login: ci-bot name: CI Bot repos: - owner: yonatangross name: my-project private: false default_branch: main topics: [typescript, testing] vercel: users: - username: yonatangross email: yonaigross@gmail.com projects: - name: my-docs framework: next # NEW in 0.4.x — drop-in seed blocks okta: users: - login: alice@example.com firstName: Alice lastName: Smith groups: [{ name: Everyone }, { name: Admins }] apps: [{ name: My Web App }] authorization_servers: - name: default audiences: ["api://default"] resend: domains: [{ name: example.com }] api_keys: [{ name: default }] # In tests: GET http://localhost:4009/inbox to assert captured emails stripe: customers: - name: Test Customer email: customer@example.com products: [{ name: Pro Plan }, { name: Starter Plan }] prices: - { product: Pro Plan, unit_amount: 4900, currency: usd, recurring: { interval: month } } - { product: Starter Plan, unit_amount: 1900, currency: usd, recurring: { interval: month } } # Webhook delivery fires on checkout.session.completed / expired mongoatlas: projects: [{ name: my-project }] clusters: [{ project: my-project, name: my-cluster }] database_users: [{ project: my-project, username: app-user }] ``` See `rules/seed-config.md` for full schema and best practices. ## Programmatic SDK > Service packages live under the `@emulators/*` scope (e.g., `@emulators/github`, `@emulators/stripe`). The programmatic API (`createEmulator`) is exported from the top-level `emulate` package. ```typescript import { createEmulator } from 'emulate' const github = await createEmulator({ service: 'github', port: 4001 }) // github.url -> 'http://localhost:4001' // State is real — create a PR and it appears in the list const res = await fetch(`${github.url}/repos/org/repo/pulls`, { method: 'POST', headers: { Authorization: 'Bearer dev_token' }, body: JSON.stringify({ title: 'Test PR', head: 'feature', base: 'main' }) }) const prs = await fetch(`${github.url}/repos/org/repo/pulls`) // -> includes the PR we just created // Cleanup github.reset() // Synchronous state wipe await github.close() // Shut down server ``` See `references/sdk-patterns.md` for advanced patterns (multi-service, lifecycle hooks). ## Webhook Delivery Emulate delivers real webhooks with HMAC-SHA256 signatures when state changes: ```typescript import crypto from 'crypto' function verifyWebhook(payload: string, signature: string, secret: string): boolean { const expected = 'sha256=' + crypto .createHmac('sha256', secret) .update(payload) .digest('hex') return crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(expected)) } ``` See `rules/webhook-setup.md` for webhook receiver patterns. ## CI Integration ```yaml # .github/workflows/test.yml jobs: test: steps: - uses: actions/checkout@v4 - name: Start emulate run: npx emulate --service github --seed .emulate/ci.yaml & - name: Wait for emulate run: sleep 2 - name: Run tests run: npm test env: GITHUB_API_BASE: http://localhost:4001 VERCEL_API_BASE: http://localhost:4000 ``` ### Parallel Test Execution Each test worker gets its own port to avoid race conditions: ```typescript // vitest.config.ts const workerPort = 4001 + parseInt(process.env.VITEST_WORKER_ID || '0') ``` See `rules/parallel-ci.md` for full parallel isolation patterns. ## Decision Matrix | Tool | When to Use | Stateful? | Platforms | |------|------------|-----------|-----------| | **emulate** (FIRST CHOICE) | GitHub/Vercel/Google/Slack/Apple/Entra/AWS/Okta/Resend/Stripe/MongoDB testing | YES | All 12 services | | Pact | Contract verification between services | No | Any | | MSW | In-browser/Node HTTP mocking | No | Any | | Nock | Node.js HTTP intercept | No | Any | | WireMock | HTTP stub server | Partial | Any | **Use emulate when:** - Testing code that calls GitHub, Vercel, Google, Slack, Apple, Entra, AWS, Okta, Resend, Stripe, or MongoDB Atlas - You need state persistence across multiple API calls in a test - You want webhook delivery with real HMAC signatures (GitHub, Stripe) - You need cascading side-effects (delete repo -> PRs cascade-delete) - You need to assert on sent emails without hitting a real provider (Resend local `/inbox`) - You need hosted Stripe checkout sessions with real redirect flow in tests **Use MSW/Nock when:** - Mocking arbitrary HTTP APIs not covered by emulate - You need in-browser interception (MSW) - Tests only need single request/response pairs ## Related Skills - `testing-integration` — Integration test patterns (emulate as first choice for API tests) - `testing-e2e` — End-to-end test patterns with emulated backends - `testing-unit` — Unit test patterns (use emulate for API-dependent units) - `security-patterns` — Auth token patterns (emulate token seeding) ## CLI Reference See `references/cli-reference.md` for all CLI flags and commands. ## SDK Patterns See `references/sdk-patterns.md` for programmatic `createEmulate()` usage.