fakeAppDAO.js

'use strict';

export default class fakeAppDAO {
    
    constructor() {
                
    }

    callServer(path, method = "GET", query = {}, data) {
        
        var endpoint = path + "|" + method;
        var returnData;
        switch(endpoint){
          case "/markets/9999|GET":
            // change this to whatever you'd actually want to return here, i.e., something that looks more like market data
            returnData = [ 
            {id: 3, name: "foo"}, 
            {id: 4, name: "bar"},
            ]
            break;
        }
        
  return new Promise(
      (resolve, reject) => {
        resolve(returnData);
      }
    );
      
  }

}

Markets.test.js

var rewire = require('rewire');
var rewireModule = require('../../test/helpers/rewire-module.js');
var dump = require('../../test/helpers/util.js').dump;
var React = require('react');
var fakeAppDao = require('../../test/helpers/fakeAppDAO.js')
describe("Market (DAO)", function() {

    var Market = rewire("./Market.js");
    var rw = {
      AppDAO: fakeAppDAO
    }
    
    rewireModule(Market,rw);

    it("returns multiple markets", function() {
        var ready  = false,
        result;
        
        runs( function() 
        {
            Market
                .fetchAll()
                .then(
                    function onResponse( data )
                    {
                        result = data;
                        ready  = true;      // continue test runner 
                    },
                    function onError( fault )
                    {
                        ready  = true;      // continue test runner 
                    }
                );
        });
 
        // Pause test runner until timeout or yourAsyncCall() responds       
        waitsFor( function() 
        {
            return result;
        }); 
        
        // Run the code that checks the expectations… 
        runs( function() 
        {
            expect( result.length ).toBeEqual( 2 );
        }); 
    });
});