如何测试 deno WebSocket 服务器？

Question

I have written a small WebSocket Server class in Typescript using deno.

Now, I want to test it. Everything works fine when I just run the server and after that close it.

But when I try to connect to the server in the testcase via new WebSocket("ws://{myserver}") I get the following error:

Test case is leaking async ops.

My Code:

Deno.test("run server", (): void => {
    const serverConfig = {
        autoServe: true,
        host: "localhost",
        port: 3045,
    };

    const server = new WSServer(serverConfig);

    console.log(server);

    const conn = new WebSocket("ws://localhost:3045");

    conn.send("hello");

    conn.close();

    assertEquals<number>(server.config.port, serverConfig.port);

    assertEquals<boolean>(server.listening, true);

    server.close();
});

Is there a solution to that?

Answer 1

I found a solution to this problem. I have to wait for the WebSocket connection to open. But when I send something on the connection and the close the connection it won't send the data and I have to close the connection, because else Deno gives me the error that

Test case is leaking async ops

So I implemented in my server code, that sends an answer to each sent data.

In the working server I will send a confirm message with a unique code.

So for the test case (currently, it doesn't do something with a confirmation message, and listens only for any message from the server) I have now:

Deno.test("run server", async () => {
    const serverConfig = {
        autoServe: true,
        host: "localhost",
        port: 3045,
    };

    const server = new WSServer(serverConfig);

    const conn = new WebSocket("ws://localhost:3045");

    const awaitOpen = (connection: WebSocket): Promise<boolean> => {
        return new Promise(resolve => {
            conn.addEventListener("open", () => {
                resolve(true);
            });
        });
    };

    const awaitResponse = (connection: WebSocket): Promise<string> => {
        return new Promise(resolve => {
            conn.addEventListener("message", (event) => {
                resolve(String(event.data));
            });
        });
    }

    await awaitOpen(conn);

    conn.send("hello");

    const response = await awaitResponse(conn);

    if (response) {
        conn.close();

        server.close();
    }

    assertEquals<number>(server.config.port, serverConfig.port);

    assertEquals<boolean>(server.listening, true);
});

I hope, this is helpful for somebody.