feat(testing): add Testing helpers (createBroker, EventCatcher, MockingCalls)

[aifunmobi]

Summary

Implements RFC #3 — Testing helpers for Moleculer.

• createBroker(options, mockServices) — Creates a real ServiceBroker with test middlewares pre-configured (logger disabled, test mode on)
• EventCatcher middleware — Intercepts emit/broadcast/broadcastLocal and records all events for assertion
• MockingCalls middleware — Intercepts broker.call, supports fluent mock API with param/meta matching

Usage

const { Testing } = require("moleculer");
const { createBroker } = Testing;

const broker = createBroker({}, [
  { name: "posts", actions: { list: jest.fn(async () => [1, 2, 3]) } }
]);

await broker.start();
await broker.call("posts.list", { limit: 5 });
// Assert events
expect(broker.test.eventEmitted("posts.updated")).toBe(true);
// Mock actions
broker.test.mockAction("users.get").withParams({ id: 5 }).returnValue({ name: "John" });

API (broker.test.*)

Events: eventEmitted, eventEmittedTimes, eventEmittedWithParams, waitForEvent, getEvents, clearEvents

Actions: mockAction (fluent: .withParams(), .withMeta(), .returnValue(), .rejectWith()), actionCalled, actionCalledTimes, actionCalledWithParams, getCalls, clearActions, clearMocks

Utility: clearAll

Test plan

• 22 tests covering all API methods
• Tests for createBroker with options, mock services, custom middlewares
• Tests for EventCatcher: emit, broadcast, broadcastLocal, waitForEvent, timeout
• Tests for MockingCalls: mock with params, reject, clear, getCalls
• Export verification tests

Design decisions

• Uses real ServiceBroker (not a fake) — middlewares wrap actual broker methods
• Middlewares follow existing moleculer middleware pattern (emit/broadcast/call hooks)
• Integrated at require("moleculer").Testing as specified in the RFC
• broker.test namespace avoids conflicts with existing broker API

Closes moleculerjs/rfcs#3

🤖 Generated with Claude Code

[aifunmobi]

Friendly ping — all checks are passing. Happy to address any feedback!

[aifunmobi]

@icebob Friendly follow-up — this implements the testing helpers from RFC #3 (createBroker, EventCatcher, MockingCalls). All Codacy checks are green. Would love any feedback!

[icebob-ai]

Closing this PR. There are multiple duplicate PRs implementing the same RFC #3, and we'll be handling the testing helpers implementation internally as part of the v0.15 release. Thank you for your interest in contributing to Moleculer.