Added type for websocketErr, implemented passing integration test for…

… the same

ably/realtime_client_integration_test.go

@@ -266,6 +266,29 @@ func TestRealtime_RTN17_HostFallback(t *testing.T) {
 	})
 }
 
+func TestRealtime_RTN17_Integration_HostFallback(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+	}))
+	defer server.Close()
+	serverURL, err := url.Parse(server.URL)
+	assert.NoError(t, err)
+
+	app, realtime := ablytest.NewRealtime(
+		ably.WithAutoConnect(false),
+		ably.WithTLS(false),
+		ably.WithUseTokenAuth(true),
+		ably.WithFallbackHosts(ably.GetEnvFallbackHosts(ablytest.Environment)),
+		ably.WithRealtimeHost(serverURL.Host))
+
+	defer safeclose(t, ablytest.FullRealtimeCloser(realtime), app)
+
+	err = ablytest.Wait(ablytest.ConnWaiter(realtime, realtime.Connect, ably.ConnectionEventConnected), nil)
+	if err != nil {
+		t.Fatalf("Error connecting host with error %v", err)
+	}
+}
+
 func checkUnique(ch chan string, typ string, n int) error {
 	close(ch)
 	uniq := make(map[string]struct{}, n)

ably/realtime_conn.go

@@ -416,7 +416,7 @@ func (c *Connection) connectWith(arg connArgs) (result, error) {
 			}
 			break
 		}
-		resp := extractHttpResponseFromConn(c.conn)
+		resp := extractHttpResponseFromError(err)
 		if hostCounter < len(hosts)-1 && canFallBack(err, resp) && c.opts.hasActiveInternetConnection() { // RTN17d, RTN17c
 			continue
 		}

ably/websocket.go

@@ -22,7 +22,21 @@ const (
 type websocketConn struct {
 	conn  *websocket.Conn
 	proto proto
-	resp  *http.Response
+}
+
+type websocketErr struct {
+	err  error
+	resp *http.Response
+}
+
+// websocketErr implements the builtin error interface.
+func (e *websocketErr) Error() string {
+	return e.err.Error()
+}
+
+// Unwrap implements the implicit interface that errors.Unwrap understands.
+func (e *websocketErr) Unwrap() error {
+	return e.err
 }
 
 func (ws *websocketConn) Send(msg *protocolMessage) error {
@@ -90,9 +104,8 @@ func dialWebsocket(proto string, u *url.URL, timeout time.Duration, agents map[s
 	}
 	// Starts a raw websocket connection with server
 	conn, resp, err := dialWebsocketTimeout(u.String(), "https://"+u.Host, timeout, agents)
-	ws.resp = resp
 	if err != nil {
-		return nil, err
+		return nil, &websocketErr{err: err, resp: resp}
 	}
 	ws.conn = conn
 	return ws, nil
@@ -126,11 +139,10 @@ func unwrapConn(c conn) conn {
 	return unwrapConn(u.Unwrap())
 }
 
-func extractHttpResponseFromConn(c conn) *http.Response {
-	unwrappedConn := unwrapConn(c)
-	websocketConn, ok := unwrappedConn.(*websocketConn)
+func extractHttpResponseFromError(err error) *http.Response {
+	wsErr, ok := err.(*websocketErr)
 	if ok {
-		return websocketConn.resp
+		return wsErr.resp
 	}
 	return nil
 }