...
function PhoneDetailCtrl($scope, $routeParams, $http) {
 $http.get('phones/' + $routeParams.phoneId + '.json').success(function(data) {
 $scope.phone = data;
 $scope.mainImageUrl = data.images[0];
 });

 $scope.setImage = function(imageUrl) {
 $scope.mainImageUrl = imageUrl;
 }
}

//PhoneDetailCtrl.$inject = ['$scope', '$routeParams', '$http'];

<img ng-src="{{mainImageUrl}}" class="phone">

...

<ul class="phone-thumbs">
 <li ng-repeat="img in phone.images">
 <img ng-src="{{img}}" ng-click="setImage(img)">
 </li>
</ul>
...

...
 describe('Phone detail view', function() {

...

 it('should display the first phone image as the main phone image', function() {
  expect(element('img.phone').attr('src')).toBe('img/phones/nexus-s.0.jpg');
 });

 it('should swap main image if a thumbnail image is clicked on', function() {
  element('.phone-thumbs li:nth-child(3) img').click();
  expect(element('img.phone').attr('src')).toBe('img/phones/nexus-s.2.jpg');

  element('.phone-thumbs li:nth-child(1) img').click();
  expect(element('img.phone').attr('src')).toBe('img/phones/nexus-s.0.jpg');
 });
 });
});

 $scope.hello = function(name) {
  alert('Hello ' + (name || 'world') + '!');
 }