---

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 jeremy@intentsolutions.io

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

# .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

// 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

// 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: 'test@example.com' });
    expect(cioMocks.identify).toHaveBeenCalledWith(
      expect.any(String),
      expect.objectContaining({ email: 'test@example.com' })
    );
  });
});

Step 4: Create Dev Scripts

{
  "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
• Test Mode Best Practices

Next Steps

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