mixpanel-mock.js

    var isDev = false;
    if (window.__env.NODE_ENV === 'development') {
      isDev = true;
    }
    if (isDev) {
      var MixpanelMock;

      MixpanelMock = (function() {
        function MixpanelMock() {
          this.init = function() {
            console.log("mixpanel.init", arguments);
          }
          this.track = function() {
            console.log("mixpanel.track", arguments);
          }
        }

        return MixpanelMock;

      })();

      window.mixpanel = new MixpanelMock();

Thanks for the gist! very helpful