Context

src/rateLimit.js was added in #14 but has no tests.

What to test

• Messages within the limit pass through normally
• The (limit + 1)th message within the window is blocked
• Client receives rateLimit:exceeded event with correct event, limit, windowMs, retryAfter fields
• After windowMs elapses, the counter resets and messages pass through again
• events filter option — rate limiting only applies to the specified events, others pass freely
• onLimitReached callback is called instead of emitting rateLimit:exceeded when provided
• Rate limit state is cleaned up from memory after socket disconnects

Setup tip

Use socket.io-client with a real server. To test window reset, advance time with Date.now mocking or simply wait windowMs ms between bursts.