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

[steven-ge007]

Description

Implements the testing helpers proposed in RFC #3. This adds three new tools for writing tests in Moleculer microservices:

createBroker(opts, mockServices)

Factory function that creates a ServiceBroker pre-configured for testing with logging disabled, test: true flag, and both testing middlewares auto-registered.

EventCatcher middleware

Captures all emit, broadcast, and broadcastLocal events for test assertions:

broker.test.eventEmitted("user.created")
broker.test.eventEmittedTimes("user.created")
broker.test.eventEmittedWithParams("user.created", { role: "admin" })
broker.test.waitForEvent("async.event")
broker.test.clearEvents()

MockingCalls middleware

Intercepts broker.call for mocking and call tracking:

broker.test.mockAction("users.get").withParams({ id: 5 }).returns({ id: 5, name: "Mock" })
broker.test.actionCalled("users.get")
broker.test.actionCalledTimes("users.get")
broker.test.actionCalledWithParams("users.get", { id: 5 })
broker.test.clearActions()

Files changed

• src/middlewares/testing.js - EventCatcher and MockingCalls middlewares
• src/middlewares/index.js - Export Testing namespace
• src/testing.js - createBroker factory function
• src/testing.d.ts - TypeScript type definitions
• index.js / index.mjs - Export Testing module
• test/unit/middlewares/testing.spec.js - 22 test cases

Test Plan

All 2356 tests pass (137 suites), 22 new tests for the testing module.

Closes moleculerjs/rfcs#3

[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.