MockWebServer expectSentWebSocketMessage

[manusa]

Description

The current MockWebServer implementation for fabric8io/mockwebserver#38 is "wrong" and doesn't behave as described in the original PR https://github.com/fabric8io/mockwebserver/pull/38/files.

When using expectSentWebSocketMessage we are using a message received through the socket to send a response (this way we can send multiple messages through the socket).

What it's inferred from the description is the implementation of a bidirectional conversation.

• The server receives an HTTP request
• The server emits a WS message.
• The server waits for a given message to be received
• The server emits a WS message

Discovered in scope of #5632 which fails randomly due to the unexpected implementation.

However the behavior is mostly for an unidirectional conversation:

• The server receives an HTTP request
• The server emits a WS message
• If the message matches the expectation, server sends an additional enqueued message after the original

Proposed fix

In order not to break the current behavior which has been in place for years, update the original test that was updated in #5664