ci: add test for websocket

vendor/github.com/gorilla/websocket/examples/chat/README.md

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+# Chat Example
+
+This application shows how to use the
+[websocket](https://github.com/gorilla/websocket) package to implement a simple
+web chat application.
+
+## Running the example
+
+The example requires a working Go development environment. The [Getting
+Started](http://golang.org/doc/install) page describes how to install the
+development environment.
+
+Once you have Go up and running, you can download, build and run the example
+using the following commands.
+
+    $ go get github.com/gorilla/websocket
+    $ cd `go list -f '{{.Dir}}' github.com/gorilla/websocket/examples/chat`
+    $ go run *.go
+
+To use the chat example, open http://localhost:8080/ in your browser.
+
+## Server
+
+The server application defines two types, `Client` and `Hub`. The server
+creates an instance of the `Client` type for each websocket connection. A
+`Client` acts as an intermediary between the websocket connection and a single
+instance of the `Hub` type. The `Hub` maintains a set of registered clients and
+broadcasts messages to the clients.
+
+The application runs one goroutine for the `Hub` and two goroutines for each
+`Client`. The goroutines communicate with each other using channels. The `Hub`
+has channels for registering clients, unregistering clients and broadcasting
+messages. A `Client` has a buffered channel of outbound messages. One of the
+client's goroutines reads messages from this channel and writes the messages to
+the websocket. The other client goroutine reads messages from the websocket and
+sends them to the hub.
+
+### Hub 
+
+The code for the `Hub` type is in
+[hub.go](https://github.com/gorilla/websocket/blob/master/examples/chat/hub.go). 
+The application's `main` function starts the hub's `run` method as a goroutine.
+Clients send requests to the hub using the `register`, `unregister` and
+`broadcast` channels.
+
+The hub registers clients by adding the client pointer as a key in the
+`clients` map. The map value is always true.
+
+The unregister code is a little more complicated. In addition to deleting the
+client pointer from the `clients` map, the hub closes the clients's `send`
+channel to signal the client that no more messages will be sent to the client.
+
+The hub handles messages by looping over the registered clients and sending the
+message to the client's `send` channel. If the client's `send` buffer is full,
+then the hub assumes that the client is dead or stuck. In this case, the hub
+unregisters the client and closes the websocket.
+
+### Client
+
+The code for the `Client` type is in [client.go](https://github.com/gorilla/websocket/blob/master/examples/chat/client.go).
+
+The `serveWs` function is registered by the application's `main` function as
+an HTTP handler. The handler upgrades the HTTP connection to the WebSocket
+protocol, creates a client, registers the client with the hub and schedules the
+client to be unregistered using a defer statement.
+
+Next, the HTTP handler starts the client's `writePump` method as a goroutine.
+This method transfers messages from the client's send channel to the websocket
+connection. The writer method exits when the channel is closed by the hub or
+there's an error writing to the websocket connection.
+
+Finally, the HTTP handler calls the client's `readPump` method. This method
+transfers inbound messages from the websocket to the hub.
+
+WebSocket connections [support one concurrent reader and one concurrent
+writer](https://godoc.org/github.com/gorilla/websocket#hdr-Concurrency). The
+application ensures that these concurrency requirements are met by executing
+all reads from the `readPump` goroutine and all writes from the `writePump`
+goroutine.
+
+To improve efficiency under high load, the `writePump` function coalesces
+pending chat messages in the `send` channel to a single WebSocket message. This
+reduces the number of system calls and the amount of data sent over the
+network.
+
+## Frontend
+
+The frontend code is in [home.html](https://github.com/gorilla/websocket/blob/master/examples/chat/home.html).
+
+On document load, the script checks for websocket functionality in the browser.
+If websocket functionality is available, then the script opens a connection to
+the server and registers a callback to handle messages from the server. The
+callback appends the message to the chat log using the appendLog function.
+
+To allow the user to manually scroll through the chat log without interruption
+from new messages, the `appendLog` function checks the scroll position before
+adding new content. If the chat log is scrolled to the bottom, then the
+function scrolls new content into view after adding the content. Otherwise, the
+scroll position is not changed.
+
+The form handler writes the user input to the websocket and clears the input
+field.