Export wstest.Pipe for in memory tests

[nhooyr]

Would be really cool to have an in memory WebSocket implementation for tests versus starting a net/http test server every test.

[nhooyr]

Not sure if this is a good idea anymore with #199 🤔

[nhooyr]

Any thoughts @coadler?

[nhooyr]

Looks like this: https://github.com/nhooyr/websocket/blob/97345d8042c26a1e56f8e3cc5b494230677e4ab0/internal/test/wstest/pipe.go#L17

[nhooyr]

// Pipe is used to create an in memory connection
// between two websockets analogous to net.Pipe.
func Pipe(dialOpts *websocket.DialOptions, acceptOpts *websocket.AcceptOptions) (clientConn, serverConn *websocket.Conn) {
    // ...
}

[nhooyr]

If I were to export it, I'd change the signature to:

func Pipe() (http.RoundTripper, http.ResponseWriter)

Any upgrade requests sent on the round tripper would wait for the given response writer to hijack and accept the WebSocket or otherwise respond.

[nhooyr]

Not sure if this is a good idea anymore as httptest makes it so easy already and I don't think there are enough scenarios where you want in memory web sockets vs abstracting away the transport and passing around messages directly. The only good scenario I can really think of is writing tests for the library which is why it exists.

[nhooyr]

Yea, going to close this for now. Only real problem is ensuring graceful shutdown in tests for which #209 is open.