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Scope

TL;DR smocket reproduces socket.io's logic layer (which socket receives which event, and why) and nothing from the reliability layer. The out-of-scope items are not unbuilt features: a mock has no real network, so there is nothing to retry, fall back from, or reconnect to. This file is that boundary.

The split follows the two layers socket.io stacks. The logic layer decides delivery and routing; the reliability layer keeps a connection alive over an unreliable network. smocket pairs a client and its server socket directly in memory, so it can reproduce the first layer exactly, and the second layer has nothing to act on.

Reproduced (logic layer)​

  • The connection concept and the sid: connect, disconnect, and socket.id.
  • emit / on event dispatch between a client and its server socket.
  • ack: a value returned to the sender, in either direction.
  • room join / leave, kept in both directions of the roster.
  • broadcast: io.to, socket.to, socket.broadcast, and except.
  • namespace isolation across io.of(name).
  • Multiple clients connected at once.
  • Room cleanup when a socket disconnects.

Not reproduced (reliability / network layer)​

None of these can exist in a mock, because a mock never opens a real connection:

  • reconnection behavior reproduction: there is no dropped connection to re-establish. (A reconnect simulation trigger, letting you force a "now disconnected" state to exercise your own reconnect handlers, is a separate planned feature, and is not this.)
  • transport fallback: there is no WebSocket or HTTP long-polling transport to fall back between.
  • heartbeat: there is no live connection to ping, so none can time out. (The disconnect a timeout would cause is still observable: socket.disconnect() delivers a reason your handler can branch on, the same way the reconnect trigger exercises your reconnect handlers.)
  • multi-server scaling (the Redis adapter, serverSideEmit): one in-memory process has no second server to reach.
  • binary encoding / engine framing: nothing is serialised onto a wire, so there are no frames to encode. On Smocket's direct in-memory event and acknowledgement paths, packets containing ArrayBuffer, an ArrayBuffer view such as a typed array or DataView, or Blob bypass the JSON snapshot and retain their existing values and references. This passthrough does not clone, detach, encode, frame, or claim per-recipient isolation for binary data.