function proxyRoutes(url) {
    it("should return `access-control-allow-origin: *`", (done) => {
      agent
        .get(url)
        .expect('access-control-allow-origin', '*')
        .end(done);
    });

    it("should return `x-content-type-options: nosniff`", (done) => {
      agent
        .get(url)
        .expect('x-content-type-options', 'nosniff')
        .end(done);
    });

    it("should return `x-robots-tag: none`", (done) => {
      agent
        .get(url)
        .expect('x-robots-tag', 'none')
        .end(done);
    });

    it("should return the correct content-type header", (done) => {
      agent.get(url)
        .expect('content-type', 'application/javascript;charset=utf-8')
        .end(done);
    });

    it("should return an etag header", (done) => {
      agent.get(url)
        .expect(res => {
          assert.isString(res.get('etag'));
        })
        .end(done);
    });

    it("should return a cache-control header with a short max-age", (done) => {
      agent.get(url)
        .expect('cache-control', 'max-age=3600, s-maxage=300')
        .end(done);
    });

    it("response should not be gzipped", (done) => {
      agent.get(url)
        .expect(res => {
          assert.isUndefined(res.get('content-encoding'));
        })
        .end(done);
    });

    it("OPTIONS should return CORS preflight headers", (done) => {
      agent
        .options(url)
        .expect(200, '')
        .expect('access-control-allow-methods', 'GET')
        .expect('access-control-max-age', '2592000')
        .expect('content-length', '0')
        .end(done);
    });
  }
These tests run on all proxy routes.

  @param {String} url
    URL to request.