Mocking Genesys Cloud EventBridge Downstream Consumers with TypeScript

What You Will Build

A TypeScript service that publishes controlled test events to Genesys Cloud EventBridge while simultaneously running a mock downstream consumer that validates payloads, enforces latency directives, isolates test state, and generates audit logs for CI/CD pipeline synchronization. This uses the Genesys Cloud PureCloud Platform Client v2 SDK and Express for the mock server. The code is written in TypeScript with Node.js.

Prerequisites

• OAuth service account with event:publish and event:read scopes
• SDK genesys-cloud-purecloud-platform-client-v2 v5.0 or higher
• Node.js 18 LTS or higher
• Dependencies: express, ajv, uuid, dotenv, @types/express, @types/node

Authentication Setup

The Genesys Cloud API requires OAuth 2.0 client credentials authentication. The SDK handles token caching and automatic refresh, but you must initialize it with valid environment variables. The following code demonstrates the explicit token acquisition flow and SDK initialization.

import { PureCloudPlatformClientV2 } from 'genesys-cloud-purecloud-platform-client-v2';
import * as dotenv from 'dotenv';

dotenv.config();

const CLIENT_ID = process.env.GENESYS_CLIENT_ID || '';
const CLIENT_SECRET = process.env.GENESYS_CLIENT_SECRET || '';
const ENV_URL = process.env.GENESYS_ENV_URL || 'https://api.mypurecloud.com';

async function acquireAccessToken(): Promise<string> {
  const response = await fetch(`${ENV_URL}/oauth/token`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body: new URLSearchParams({
      grant_type: 'client_credentials',
      client_id: CLIENT_ID,
      client_secret: CLIENT_SECRET,
      scope: 'event:publish event:read'
    })
  });

  if (!response.ok) {
    const errorBody = await response.text();
    throw new Error(`OAuth token request failed: ${response.status} ${response.statusText} - ${errorBody}`);
  }

  const data = await response.json();
  return data.access_token;
}

const platformClient = new PureCloudPlatformClientV2();
platformClient.setEnvironment(ENV_URL);
platformClient.loginClientCredentials(CLIENT_ID, CLIENT_SECRET, ['event:publish', 'event:read']);

// Verify authentication readiness
(async () => {
  try {
    const token = await acquireAccessToken();
    console.log('Authentication successful. Token acquired.');
  } catch (error) {
    console.error('Authentication failed:', (error as Error).message);
    process.exit(1);
  }
})();

HTTP Request/Response Cycle (OAuth Token)

POST /oauth/token HTTP/1.1
Host: api.mypurecloud.com
Content-Type: application/x-www-form-urlencoded

grant_type=client_credentials&client_id=YOUR_CLIENT_ID&client_secret=YOUR_CLIENT_SECRET&scope=event:publish%20event:read

HTTP/1.1 200 OK
Content-Type: application/json

{
  "access_token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "token_type": "bearer",
  "expires_in": 3600,
  "scope": "event:publish event:read"
}

Implementation

Step 1: Construct Mock Payloads with Schema Validation and Depth Limits

You must validate incoming mock payloads against strict schema constraints to prevent malformed data from entering your test environment. The Genesys Cloud EventBridge API expects structured JSON with specific nesting rules. This step enforces a maximum simulation depth to avoid stack overflow or memory exhaustion during recursive payload generation.

import Ajv from 'ajv';

const ajv = new Ajv({ allErrors: true, strict: true });

const MOCK_PAYLOAD_SCHEMA = {
  type: 'object',
  required: ['consumerId', 'stubMatrix', 'latencyDirective', 'eventType', 'payload'],
  properties: {
    consumerId: { type: 'string', format: 'uuid' },
    stubMatrix: { type: 'array', items: { type: 'object' } },
    latencyDirective: { type: 'number', minimum: 0, maximum: 5000 },
    eventType: { type: 'string', pattern: '^event\\.[a-zA-Z0-9_]+$' },
    payload: { type: 'object' }
  },
  additionalProperties: false
};

const validateMockPayload = ajv.compile(MOCK_PAYLOAD_SCHEMA);
const MAX_SIMULATION_DEPTH = 5;

function calculateDepth(obj: unknown, currentDepth: number = 0): number {
  if (typeof obj !== 'object' || obj === null) return currentDepth;
  const depth = currentDepth + 1;
  if (depth > MAX_SIMULATION_DEPTH) {
    throw new Error(`Maximum simulation depth limit of ${MAX_SIMULATION_DEPTH} exceeded to prevent mocking failure.`);
  }
  const values = Object.values(obj as Record<string, unknown>);
  return Math.max(...values.map((val) => calculateDepth(val, currentDepth)));
}

export function validateAndSanitizePayload(data: unknown): boolean {
  const isValid = validateMockPayload(data);
  if (!isValid) {
    console.error('Schema validation failed:', validateMockPayload.errors);
    return false;
  }
  try {
    calculateDepth(data);
  } catch (error) {
    console.error('Depth validation failed:', (error as Error).message);
    return false;
  }
  return true;
}

Step 2: Implement Atomic PUT State Isolation and Mock Consumer Endpoint

Integration testing requires atomic state isolation to prevent test collisions. The PUT operation registers a stub matrix and latency directive for a specific consumer ID. The mock consumer endpoint then applies the latency directive, verifies response signatures, and runs edge case verification pipelines.

import express, { Request, Response } from 'express';
import { v4 as uuidv4 } from 'uuid';
import { validateAndSanitizePayload } from './validation';

const app = express();
app.use(express.json());

const stateStore = new Map<string, Record<string, unknown>>();

app.put('/api/v2/events/stub/:consumerId', (req: Request, res: Response) => {
  const { consumerId } = req.params;
  const payload = req.body;

  if (!validateAndSanitizePayload(payload)) {
    res.status(400).json({ errors: validateMockPayload.errors });
    return;
  }

  const isolationToken = uuidv4();
  stateStore.set(`${consumerId}:${isolationToken}`, {
    stubMatrix: payload.stubMatrix,
    latencyDirective: payload.latencyDirective,
    timestamp: new Date().toISOString(),
    isolationToken
  });

  res.status(200).json({ isolationToken, consumerId, status: 'state_isolated' });
});

HTTP Request/Response Cycle (State Isolation)

PUT /api/v2/events/stub/550e8400-e29b-41d4-a716-446655440000 HTTP/1.1
Host: localhost:3000
Content-Type: application/json

{
  "consumerId": "550e8400-e29b-41d4-a716-446655440000",
  "stubMatrix": [{"key": "routing_priority", "value": 1}],
  "latencyDirective": 150,
  "eventType": "event.conversation.created",
  "payload": {"id": "test-conv-001", "type": "voice", "direction": "inbound"}
}

HTTP/1.1 200 OK
Content-Type: application/json

{
  "isolationToken": "a3f1c9d2-8844-4b7a-9c12-001122334455",
  "consumerId": "550e8400-e29b-41d4-a716-446655440000",
  "status": "state_isolated"
}

Step 3: Mock Consumer Endpoint with Signature Checking and Edge Case Verification

The consumer endpoint simulates downstream processing. It retrieves the isolated state, applies the latency directive, verifies cryptographic signatures, and validates edge cases like malformed timestamps or missing required fields.

app.post('/api/v2/events/consumer/:consumerId', async (req: Request, res: Response) => {
  const { consumerId } = req.params;
  const eventPayload = req.body;
  const startTime = Date.now();

  const stateKey = Array.from(stateStore.keys()).find(k => k.startsWith(`${consumerId}:`));
  if (!stateKey) {
    res.status(403).json({ error: 'No active isolation state found' });
    return;
  }

  const state = stateStore.get(stateKey) as Record<string, unknown>;
  const latency = Number(state.latencyDirective) || 0;

  await new Promise(resolve => setTimeout(resolve, latency));

  const expectedSignature = Buffer.from(JSON.stringify(eventPayload.payload || {})).toString('base64');
  const providedSignature = req.headers['x-mock-signature'] as string;

  if (providedSignature && providedSignature !== expectedSignature) {
    res.status(401).json({ error: 'Response signature verification failed' });
    return;
  }

  if (!eventPayload.timestamp || isNaN(new Date(eventPayload.timestamp).getTime())) {
    res.status(400).json({ error: 'Invalid timestamp format in event payload' });
    return;
  }

  res.status(200).json({ status: 'processed', isolationToken: state.isolationToken, latencyApplied: latency });
});

Step 4: CI/CD Synchronization, Metrics Tracking, and Audit Logging

You must synchronize mock events with external CI/CD pipelines, track latency and success rates, and generate audit logs for test governance. This step wraps the consumer logic with metrics collection and webhook synchronization.

interface MockMetrics {
  totalEvents: number;
  successfulEvents: number;
  failedEvents: number;
  avgLatency: number;
}

const metrics: MockMetrics = { totalEvents: 0, successfulEvents: 0, failedEvents: 0, avgLatency: 0 };
const auditLog: string[] = [];

async function syncWithCICDWebhook(payload: Record<string, unknown>): Promise<void> {
  const webhookUrl = process.env.CICD_WEBHOOK_URL || 'http://localhost:3000/cicd/sync';
  try {
    const response = await fetch(webhookUrl, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(payload)
    });
    if (!response.ok) {
      auditLog.push(`[${new Date().toISOString()}] CICD_WEBHOOK_FAILED status=${response.status}`);
    }
  } catch (error) {
    auditLog.push(`[${new Date().toISOString()}] CICD_WEBHOOK_ERROR message=${(error as Error).message}`);
  }
}

app.post('/api/v2/events/consumer/:consumerId', async (req: Request, res: Response) => {
  const { consumerId } = req.params;
  const eventPayload = req.body;
  const startTime = Date.now();

  metrics.totalEvents++;
  auditLog.push(`[${new Date().toISOString()}] EVENT_RECEIVED consumerId=${consumerId}`);

  const stateKey = Array.from(stateStore.keys()).find(k => k.startsWith(`${consumerId}:`));
  if (!stateKey) {
    metrics.failedEvents++;
    auditLog.push(`[${new Date().toISOString()}] STATE_MISMATCH consumerId=${consumerId} action=REJECT`);
    await syncWithCICDWebhook({ type: 'mock_failure', consumerId, reason: 'state_mismatch' });
    res.status(403).json({ error: 'No active isolation state found' });
    return;
  }

  const state = stateStore.get(stateKey) as Record<string, unknown>;
  const latency = Number(state.latencyDirective) || 0;
  await new Promise(resolve => setTimeout(resolve, latency));

  const expectedSignature = Buffer.from(JSON.stringify(eventPayload.payload || {})).toString('base64');
  const providedSignature = req.headers['x-mock-signature'] as string;

  if (providedSignature && providedSignature !== expectedSignature) {
    metrics.failedEvents++;
    auditLog.push(`[${new Date().toISOString()}] SIGNATURE_MISMATCH consumerId=${consumerId}`);
    await syncWithCICDWebhook({ type: 'mock_failure', consumerId, reason: 'signature_mismatch' });
    res.status(401).json({ error: 'Response signature verification failed' });
    return;
  }

  if (!eventPayload.timestamp || isNaN(new Date(eventPayload.timestamp).getTime())) {
    metrics.failedEvents++;
    auditLog.push(`[${new Date().toISOString()}] EDGE_CASE_INVALID_TIMESTAMP consumerId=${consumerId}`);
    await syncWithCICDWebhook({ type: 'mock_failure', consumerId, reason: 'invalid_timestamp' });
    res.status(400).json({ error: 'Invalid timestamp format' });
    return;
  }

  metrics.successfulEvents++;
  const elapsed = Date.now() - startTime;
  metrics.avgLatency = ((metrics.avgLatency * (metrics.totalEvents - 1)) + elapsed) / metrics.totalEvents;

  auditLog.push(`[${new Date().toISOString()}] EVENT_PROCESSED consumerId=${consumerId} latency=${elapsed}ms`);
  await syncWithCICDWebhook({ type: 'mock_success', consumerId, latency: elapsed });

  res.status(200).json({ status: 'processed', isolationToken: state.isolationToken, latencyApplied: latency });
});

export { app, metrics, auditLog };

Complete Working Example

The following module combines authentication, validation, state isolation, consumer mocking, metrics tracking, and Genesys Cloud event publishing with 429 retry logic. Save this as index.ts and run with ts-node index.ts.

import { PureCloudPlatformClientV2 } from 'genesys-cloud-purecloud-platform-client-v2';
import * as dotenv from 'dotenv';
import express, { Request, Response } from 'express';
import { v4 as uuidv4 } from 'uuid';
import Ajv from 'ajv';

dotenv.config();

const CLIENT_ID = process.env.GENESYS_CLIENT_ID || '';
const CLIENT_SECRET = process.env.GENESYS_CLIENT_SECRET || '';
const ENV_URL = process.env.GENESYS_ENV_URL || 'https://api.mypurecloud.com';

const platformClient = new PureCloudPlatformClientV2();
platformClient.setEnvironment(ENV_URL);
platformClient.loginClientCredentials(CLIENT_ID, CLIENT_SECRET, ['event:publish', 'event:read']);

const ajv = new Ajv({ allErrors: true, strict: true });
const MOCK_PAYLOAD_SCHEMA = {
  type: 'object',
  required: ['consumerId', 'stubMatrix', 'latencyDirective', 'eventType', 'payload'],
  properties: {
    consumerId: { type: 'string', format: 'uuid' },
    stubMatrix: { type: 'array', items: { type: 'object' } },
    latencyDirective: { type: 'number', minimum: 0, maximum: 5000 },
    eventType: { type: 'string', pattern: '^event\\.[a-zA-Z0-9_]+$' },
    payload: { type: 'object' }
  },
  additionalProperties: false
};
const validateMockPayload = ajv.compile(MOCK_PAYLOAD_SCHEMA);
const MAX_SIMULATION_DEPTH = 5;

function calculateDepth(obj: unknown, currentDepth: number = 0): number {
  if (typeof obj !== 'object' || obj === null) return currentDepth;
  const depth = currentDepth + 1;
  if (depth > MAX_SIMULATION_DEPTH) throw new Error(`Maximum simulation depth limit of ${MAX_SIMULATION_DEPTH} exceeded.`);
  return Math.max(...Object.values(obj as Record<string, unknown>).map((val) => calculateDepth(val, currentDepth)));
}

function validateAndSanitizePayload(data: unknown): boolean {
  const isValid = validateMockPayload(data);
  if (!isValid) return false;
  try { calculateDepth(data); } catch { return false; }
  return true;
}

const app = express();
app.use(express.json());
const stateStore = new Map<string, Record<string, unknown>>();
const metrics = { totalEvents: 0, successfulEvents: 0, failedEvents: 0, avgLatency: 0 };
const auditLog: string[] = [];

app.put('/api/v2/events/stub/:consumerId', (req: Request, res: Response) => {
  if (!validateAndSanitizePayload(req.body)) {
    res.status(400).json({ errors: validateMockPayload.errors });
    return;
  }
  const isolationToken = uuidv4();
  stateStore.set(`${req.params.consumerId}:${isolationToken}`, {
    stubMatrix: req.body.stubMatrix,
    latencyDirective: req.body.latencyDirective,
    timestamp: new Date().toISOString(),
    isolationToken
  });
  res.status(200).json({ isolationToken, consumerId: req.params.consumerId, status: 'state_isolated' });
});

app.post('/api/v2/events/consumer/:consumerId', async (req: Request, res: Response) => {
  const startTime = Date.now();
  metrics.totalEvents++;
  auditLog.push(`[${new Date().toISOString()}] EVENT_RECEIVED consumerId=${req.params.consumerId}`);

  const stateKey = Array.from(stateStore.keys()).find(k => k.startsWith(`${req.params.consumerId}:`));
  if (!stateKey) {
    metrics.failedEvents++;
    res.status(403).json({ error: 'No active isolation state found' });
    return;
  }

  const state = stateStore.get(stateKey) as Record<string, unknown>;
  await new Promise(resolve => setTimeout(resolve, Number(state.latencyDirective) || 0));

  const expectedSig = Buffer.from(JSON.stringify(req.body.payload || {})).toString('base64');
  if (req.headers['x-mock-signature'] && req.headers['x-mock-signature'] !== expectedSig) {
    metrics.failedEvents++;
    res.status(401).json({ error: 'Response signature verification failed' });
    return;
  }

  if (!req.body.timestamp || isNaN(new Date(req.body.timestamp).getTime())) {
    metrics.failedEvents++;
    res.status(400).json({ error: 'Invalid timestamp format' });
    return;
  }

  metrics.successfulEvents++;
  const elapsed = Date.now() - startTime;
  metrics.avgLatency = ((metrics.avgLatency * (metrics.totalEvents - 1)) + elapsed) / metrics.totalEvents;
  auditLog.push(`[${new Date().toISOString()}] EVENT_PROCESSED consumerId=${req.params.consumerId} latency=${elapsed}ms`);
  res.status(200).json({ status: 'processed', isolationToken: state.isolationToken });
});

async function publishTestEvent(eventBody: Record<string, unknown>, maxRetries = 3) {
  for (let attempt = 1; attempt <= maxRetries; attempt++) {
    try {
      const response = await platformClient.Event.publishEvent(eventBody);
      auditLog.push(`[${new Date().toISOString()}] GENESYS_PUBLISH_SUCCESS eventId=${response.body.id}`);
      return response.body;
    } catch (error: any) {
      const status = error.status || error.response?.status;
      if (status === 429 && attempt < maxRetries) {
        const retryAfter = parseInt(error.headers?.['retry-after'] || '2', 10);
        auditLog.push(`[${new Date().toISOString()}] RATE_LIMITED retry=${attempt} retryAfter=${retryAfter}s`);
        await new Promise(resolve => setTimeout(resolve, retryAfter * 1000));
        continue;
      }
      throw new Error(`Genesys Cloud publish failed: ${status} - ${error.message}`);
    }
  }
}

app.get('/api/v2/metrics', (req: Request, res: Response) => {
  res.json(metrics);
});

app.get('/api/v2/audit', (req: Request, res: Response) => {
  res.json(auditLog);
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Mock EventBridge consumer running on port ${PORT}`);
});

Common Errors & Debugging

Error: 401 Unauthorized

• Cause: The OAuth token expired, the client credentials are invalid, or the event:publish scope is missing.
• Fix: Verify environment variables contain valid values. Ensure the service account has the event:publish scope assigned in the Genesys Cloud admin console. The SDK automatically refreshes tokens, but initial login must succeed.
• Code Fix: Check platformClient.loginClientCredentials returns without throwing. Log error.status and error.message during initialization.

Error: 429 Too Many Requests

• Cause: Genesys Cloud EventBridge enforces rate limits on event publishing. High-frequency test runs trigger throttling.
• Fix: Implement exponential backoff with Retry-After header parsing. The complete example includes a retry loop that respects the retry-after header and waits before attempting the next publish.
• Code Fix: Monitor auditLog for RATE_LIMITED entries. Adjust test concurrency to stay within API limits.

Error: 400 Bad Request (Schema or Depth Validation)

• Cause: The mock payload contains nested objects exceeding MAX_SIMULATION_DEPTH or violates the AJV schema constraints.
• Fix: Flatten payload structures before submission. Verify latencyDirective falls between 0 and 5000. Ensure consumerId matches UUID format.
• Code Fix: Run validateAndSanitizePayload before sending to the PUT endpoint. Inspect validateMockPayload.errors for precise field violations.

Error: 403 Forbidden (State Isolation Mismatch)

• Cause: The consumer endpoint receives an event without a prior atomic PUT registration for that consumerId.
• Fix: Always execute the /api/v2/events/stub/:consumerId PUT request before publishing events. The mock server maintains strict state isolation to prevent cross-test contamination.
• Code Fix: Implement a test harness that sequences PUT registration before POST event delivery.

Official References

• Genesys Cloud Event API Documentation
• Genesys Cloud OAuth 2.0 Client Credentials Flow
• PureCloud Platform Client v2 SDK Reference
• AJV Schema Validation Documentation