Remove all `include ActiveSupport::Testing::MethodCallAssertions`
in actioncable's tests since we can do it only in `ActionCable::TestCase`
in order to prevent code duplication.
We use the same approach for other modules of Rails.
* Use separate stream handler builders for easy override and testing.
* Fix worker pool execution that was silently failing since it only
expected connection receivers.
Sparked by code in #24162.
Alternate implementation of #24162 with tests. The code had diverged
too far on master to pull that implemenation directly.
Fixes#23778Close#24162
[Mattew Draper & Sean Griffin]
* Introduce a connection coder responsible for encoding Cable messages
as WebSocket messages, defaulting to `ActiveSupport::JSON` and duck-
typing to any object responding to `#encode` and `#decode`.
* Consolidate encoding responsibility to the connection. No longer
explicitly JSON-encode from channels or other sources. Pass Cable
messages as Hashes to `#transmit` and rely on it to encode.
* Introduce stream encoders responsible for decoding pubsub messages.
Preserve the currently raw encoding, but make it easy to use JSON.
Same duck type as the connection encoder.
* Revert recent data normalization/quoting (#23649) which treated
`identifier` and `data` values as nested JSON objects rather than as
opaque JSON-encoded strings. That dealt us an awkward hand where we'd
decode JSON strings… or not, but always encode as JSON. Embedding
JSON object values directly is preferably, no extra JSON encoding,
but that should be a purposeful protocol version change rather than
ambiguously, inadvertently supporting multiple message formats.
ActionCable does some things behind the scenes that expects these
"broadcasting"s or "channel"s to be strings. However it's not
immediately obvious that the value must be a string. So adding this
conversion ensures things work as expected.
