app.js

var App;

function App() {
  this.panda = "sad";
}

module.exports = App;

appSpec.js

var App, app, expect;
App = require("../../src/server/server.js"); //Server side code
expect = require("expect.js");
app = new App();

describe("server testing", function() {
  it("should work", function() {
    expect(typeof app).to.be("object");
  });
});