Testing angular controller initialisation with different conditions - angularjs

Question

I have a controller that takes a dependency on a service, and as part of it's initialisation calls a function on the service. Here's a contrived example:
describe('tests', function() {
var _scope, service, serviceValue = 'value';
beforeEach(module('app'));
beforeEach(inject(['$rootScope','$controller', function($rootScope, $controller) {
_scope = $rootScope.$new();
service = {
get: function(key) {
return serviceValue;
}
};
$controller('myController', {
'$scope': _scope,
'service': service
});
}]));
describe('initialisation', function() {
describe('key exists', function() {
it('should find the key', function() {
expect(_scope.message).toBe('found the key');
});
});
describe('key does not exist', function() {
beforeEach(function() {
serviceValue = undefined;
});
it('should not find the key', function() {
expect(_scope.message).toBe('did not find the key');
});
});
});
});
angular.module('app').controller('myController', ['$scope','service',
function($scope, service) {
if(service.get('key') === 'value') {
$scope.message = 'found the key';
} else {
$scope.message = 'did not find the key';
}
});
The tests for when the key does not exist fail because the controller initialisation has run in the first beforeEach, before the next beforeEach runs to change the service return value.
I can get around this by recreating the whole controller in the beforeEach of the 'key does not exist' tests, but this seems wrong to me, as it initialises the controller twice for the test. Is there a way to get the controller initialisation to run for every test, but after all other beforeEach functions have run.
Is this the right way to be initialising controllers? Am I missing some feature of jasmine?

Answer 1

Creating the controller for each test is the recommended way, especially when you have initialization logic.
I would however use Jasmine's spyOn to set up what the service returns and tracking calls to it, instead of modifying internal values of a mocked or real service.
Inject the real service and save it in a variable, and define a function that creates the controller:
describe('tests', function() {
var $scope, createController, service;
beforeEach(function() {
module('app');
inject(function($rootScope, $controller, _service_) {
$scope = $rootScope.$new();
service = _service_;
createController = function() {
$controller('myController', {
'$scope': $scope,
'service': service
});
};
});
});
For each test use spyOn to intercept calls to the service and decide what it should return, then create the controller:
describe('initialisation', function() {
it('should find the key', function() {
spyOn(service, 'get').and.returnValue('value');
createController();
expect($scope.message).toBe('found the key');
});
it('should not find the key', function() {
spyOn(service, 'get').and.returnValue(undefined);
createController();
expect($scope.message).toBe('did not find the key');
});
});
Demo: http://plnkr.co/edit/BMniTis1RbOR0h5O4kZi?p=preview
As spyOn sets up tracking you can now for example also make sure the service only gets called once on controller initilization:
spyOn(service, 'get').and.returnValue('value');
expect(service.get.calls.count()).toEqual(0);
createController();
expect(service.get.calls.count()).toEqual(1);
Note: The examples above use Jasmine 2.0. Syntaxes will have to be slightly modified for older versions.