title: Firebase App named '[DEFAULT]' already exists (app/duplicate-app)
body: <p>Hi I am trying to unit test while developing a simple web with AngularJS + Firebase, but I have a problem defining the spec and trying the test runner</p>
  
  <p>myProject/test/spec/main.js :</p>
  
  <pre><code>describe('Controller: MainCtrl', function() {
  
  var MainCtrl, scope
  
  beforeEach(module('MainApp'));
  
  beforeEach(inject(function ($controller, $rootScope) {
      scope = $rootScope.$new();
      MainCtrl = $controller('MainCtrl', {
          $scope: scope
      })
  }));
  
  it('should....',function(){
      expect(true).toBe(true)
  })
  it('should2....',function(){
      expect(false).toBe(false)
  })
  });
  </code></pre>
  
  <p>result:</p>
  
  <pre><code>PhantomJS 2.1.1 (Mac OS X 0.0.0) Controller: MainCtrl should.... FAILED
  Error: [$injector:modulerr] Failed to instantiate module MainApp due 
  to: Firebase: Firebase App named '[DEFAULT]' already exists 
  (app/duplicateapp).
  </code></pre>
  
  <p>However, defining the spec once is not a problem. For example:</p>
  
  <pre><code>it('should....',function(){
     expect(true).toBe(true)
  })
  </code></pre>
  
  <p>I do not know why this is the reason I give a hint to me</p>
  
  <p>Here is the project I am developing.</p>
  
  <p><a href="https://github.com/parkwookyun/firebase-angular-board" rel="noreferrer">https://github.com/parkwookyun/firebase-angular-board</a></p>