@Test
void join() {

    var channel = new ChannelImpl<TestWebSocketMessage, TestWebSocketMessage>(null, context, null);
    channel.join("room1");
    List<Channel<TestWebSocketMessage>> room = context.room("room1");
    assertThat(room).containsOnly(channel);
    channel.leave("room1");
    assertThat(context.room("room1")).isEmpty();
}