customerio-local-dev-loop by jeremylongshore

---
name: customerio-local-dev-loop
description: |
  Configure Customer.io local development workflow.
  Use when setting up local testing, development environment,
  or offline development for Customer.io integrations.
  Trigger with phrases like "customer.io local dev", "test customer.io locally",
  "customer.io development environment", "customer.io sandbox".
allowed-tools: Read, Write, Edit, Bash(npm:*), Bash(pip:*), Grep
version: 1.0.0
license: MIT
author: Jeremy Longshore <[email protected]>
---

# Customer.io Local Dev Loop

## Overview
Set up an efficient local development workflow for Customer.io integrations with proper testing and isolation.

## Prerequisites
- Customer.io SDK installed
- Separate development workspace in Customer.io (recommended)
- Environment variable management tool (dotenv)

## Instructions

### Step 1: Create Environment Configuration
```bash
# .env.development
CUSTOMERIO_SITE_ID=dev-site-id
CUSTOMERIO_API_KEY=dev-api-key
CUSTOMERIO_REGION=us

# .env.production
CUSTOMERIO_SITE_ID=prod-site-id
CUSTOMERIO_API_KEY=prod-api-key
CUSTOMERIO_REGION=us
```

### Step 2: Create Dev Client Wrapper
```typescript
// lib/customerio.ts
import { TrackClient, RegionUS, RegionEU } from '@customerio/track';

const getRegion = () => {
  return process.env.CUSTOMERIO_REGION === 'eu' ? RegionEU : RegionUS;
};

const isDevelopment = process.env.NODE_ENV !== 'production';

class CustomerIOClient {
  private client: TrackClient;
  private dryRun: boolean;

  constructor() {
    this.client = new TrackClient(
      process.env.CUSTOMERIO_SITE_ID!,
      process.env.CUSTOMERIO_API_KEY!,
      { region: getRegion() }
    );
    this.dryRun = process.env.CUSTOMERIO_DRY_RUN === 'true';
  }

  async identify(userId: string, attributes: Record<string, any>) {
    if (this.dryRun) {
      console.log('[DRY RUN] Identify:', { userId, attributes });
      return;
    }
    if (isDevelopment) {
      attributes._dev = true;
      attributes._dev_timestamp = new Date().toISOString();
    }
    return this.client.identify(userId, attributes);
  }

  async track(userId: string, eventName: string, data?: Record<string, any>) {
    if (this.dryRun) {
      console.log('[DRY RUN] Track:', { userId, eventName, data });
      return;
    }
    const eventData = {
      name: isDevelopment ? `dev_${eventName}` : eventName,
      data: { ...data, _dev: isDevelopment }
    };
    return this.client.track(userId, eventData);
  }
}

export const cio = new CustomerIOClient();
```

### Step 3: Set Up Test Helpers
```typescript
// test/helpers/customerio-mock.ts
import { vi } from 'vitest';

export const mockCustomerIO = () => {
  const mocks = {
    identify: vi.fn().mockResolvedValue(undefined),
    track: vi.fn().mockResolvedValue(undefined),
    trackAnonymous: vi.fn().mockResolvedValue(undefined),
  };

  vi.mock('@customerio/track', () => ({
    TrackClient: vi.fn().mockImplementation(() => mocks),
    RegionUS: 'us',
    RegionEU: 'eu',
  }));

  return mocks;
};

// Usage in tests
import { mockCustomerIO } from './helpers/customerio-mock';

describe('User Registration', () => {
  const cioMocks = mockCustomerIO();

  it('identifies user on signup', async () => {
    await registerUser({ email: '[email protected]' });
    expect(cioMocks.identify).toHaveBeenCalledWith(
      expect.any(String),
      expect.objectContaining({ email: '[email protected]' })
    );
  });
});
```

### Step 4: Create Dev Scripts
```json
{
  "scripts": {
    "dev:cio": "CUSTOMERIO_DRY_RUN=true ts-node scripts/test-customerio.ts",
    "dev:cio:live": "dotenv -e .env.development ts-node scripts/test-customerio.ts",
    "test:cio": "vitest run --reporter=verbose tests/customerio/"
  }
}
```

## Output
- Environment-aware Customer.io client
- Dry-run mode for safe testing
- Test mocks for unit testing
- Prefixed events for development isolation

## Error Handling
| Error | Cause | Solution |
|-------|-------|----------|
| Wrong environment | Env vars not loaded | Use dotenv or env-specific files |
| Dev events in prod | Environment check failed | Verify NODE_ENV is set correctly |
| Mock not working | Import order issue | Mock before importing client |

## Resources
- [Customer.io Workspaces](https://customer.io/docs/workspaces/)
- [Test Mode Best Practices](https://customer.io/docs/test-mode/)

## Next Steps
After setting up local dev, proceed to `customerio-sdk-patterns` for production-ready patterns.