function nonProxyRoutes(url) {
    // Just in case someone makes a silly mistake.
    it("should not return an access-control-allow-origin header", (done) => {
      agent
        .get(url)
        .expect(res => {
          assert.isUndefined(res.get('access-control-allow-origin'));
        })
        .end(done);
    });
  }
These tests run on all non-proxy routes.

  @param {String} url
    URL to request.