code: function(app, options) {
    app.post(WRITE_COVERAGE,
      bodyParser,
      (req, res) => {
        let map = istanbul.libCoverage.createCoverageMap();
        coverageHandler(map, options, req, res);
      },
      logError);
  }
docs: Used when app is in dev mode (`ember serve`). Creates a new coverage map on every request.