How can I test $watch in Angular - angularjs

Question

I'm trying to unit test $scope.$watch in controller, I don't know why $scope.$apply() in test code causes unexpected request error such as Error: Unexpected request: GET /locales/en.json. That's other part of the controller, why it's involved here?
However this error will not occur if I comment $scope.$apply, but of course $watch cannot be triggered in that case. Do I have to mock those requests like $httpBackend.whenGET('/locales/en.json').respond(''); ?
controller:
$scope.$watch(function(){
return $location.path();
}, function() {
$scope.currentPath = $location.path().match(/\/[a-z0-9A-Z_]*/)[0];
$scope.currentNav = 'menu.' + $scope.currentPath.replace('/', '');
});
jasmine:
describe('homeController', function() {
beforeEach(module('homeApp'));
var $rootScope, $scope, controller, $httpBackend, $location, $route, $window
beforeEach(inject(function($controller, _$rootScope_, _$httpBackend_, _$location_, _$route_, _$window_) {
$rootScope = _$rootScope_;
$scope = $rootScope.$new();
controller = $controller('homeController', {$scope: $scope});
$httpBackend = _$httpBackend_;
$location = _$location_;
$route = _$route_;
$window = _$window_;
}));
describe('watch path', function() {
it('should change currentPath and currentNav', function() {
$location.path('/dashboard');
$scope.$apply();
$location.path('/images');
$scope.$apply();
expect($scope.currentPath).toBe('/images')
expect($scope.currentNav).toBe('menu.images')
})
})
})
update:
It's working after mocking all the http requests required. But still want to know why it affects those requests.

Answer 1

In above example you are not watching anything. $watch function will be called when value of object being watched changes. It will return you both old and new value for object.
$scope.someValue = 0;
$scope.$watch(
"$scope.someValue",
function handleFooChange(newValue, oldValue) {
console.log("$scope.someValue:", newValue);
}
);
Here someValue is being watched for change. Once value of someValue will change, callback function of $watch will be called.