app.js

var IndexRoutes = require( 'index' );

var indexRoutes;

indexRoutes = routes.generate({
    config = options.config;
    logger = options.logger;
    Metric = options.Metric;
});

app.get( '/something', indexRoutes.awesome );

index.js

var async = require( 'async' );

var IndexRoutes = function( options ) {
    config = options.config;
    logger = options.logger;
    Metric = options.Metric;
    
    awesomeRouteMethod = function( req, res ) {
    };

    return {
        awesome: awesomeRouteMethod;
    };
};

module.exports = IndexRoutes;

test.js

var IndexRoutes = require( 'index' );

var indexRoutes;

// define fake objects
// ...

indexRoutes = routes.generate({
    config = fakeOptions;
    logger = fakeLogger;
    Metric = fakeMetrics;
});

describe( 'awesome route', function() {
    it( 'should call Metrics with options', function( done ) {
      indexRoutes.awesome( fakeReq, {
        jsonp: function() {
          expect(fakeMetrics.calledOnce).to.be.true;
          done();
        }
      });
      
    })
})