How to use the @microsoft/signalr.DefaultHttpClient function in @microsoft/signalr

it("over LongPolling it sends DELETE request and waits for poll to terminate", async (done) => {
        // Create an HTTP client to capture the poll
        const defaultClient = new DefaultHttpClient(TestLogger.instance);

        class TestClient extends HttpClient {
            public pollPromise: Promise | null;

            constructor() {
                super();
                this.pollPromise = null;
            }

            public send(request: HttpRequest): Promise {
                if (request.method === "GET") {
                    this.pollPromise = defaultClient.send(request);
                    return this.pollPromise;
                }
                return defaultClient.send(request);
            }