how to test function in controller scope executed by event - angularjs

Question

function in controller:
angular.module('myApp').controller('MyController', function(){
$scope.f = function($event){
$event.preventDefault();
//logic
return data;
}
})
describe('MyController', function(){
'use strict';
var MyController,
$scope;
beforeEach(module('myApp'));
beforeEach($inject(function($rootScope, $controller){
$scope = $rootScope.$new();
MyController = $controller('MyController', {
$scope: $scope
})
}));
})
it('should...', function(){
//fire event and expect data
})
$scope.f function is used in directive, it can be executed by ng-click="f($event)"
what is right way for fire event in unit test?

Answer 1

Short Answer
You don't need to fire the event. You have access to the scope, which has the function you want to test. This means you just execute the function, then assert. It will look something like this:
it('should call preventDefault on the given event', function(){
var testEvent = $.Event('someEvent');
$scope.f(testEvent);
expect(testEvent.isDefaultPrevented()).toBe(true);
});
See the following:
jQuery Event Object
event.isDefaultPrevented()
Full Spec
Also - your it block should be inside your describe block, so that it has access to the $scope field. It should look more like this:
describe('MyController', function(){
'use strict';
var MyController,
$scope;
beforeEach(module('myApp'));
beforeEach($inject(function($rootScope, $controller){
$scope = $rootScope.$new();
MyController = $controller('MyController', {
$scope: $scope
})
}));
it('should call preventDefault on the given event', function(){
var testEvent = $.Event('someEvent');
$scope.f(testEvent);
expect(testEvent.isDefaultPrevented()).toBe(true);
});
})
A Note About Structure
Don't be afraid to use the describe blocks to structure your tests. Imagine you had another function on the $scope called f2, then you would probably want to partition your spec file up more like this:
describe('MyController', function(){
'use strict';
var MyController,
$scope;
beforeEach(module('myApp'));
beforeEach($inject(function($rootScope, $controller){
$scope = $rootScope.$new();
MyController = $controller('MyController', {
$scope: $scope
})
}));
describe('$scope', function() {
describe('.f()', function() {
// tests related to only the .f() function
});
describe('.f2()', function() {
// tests related to only the .f2() function
});
});
})
This has the benefit that when a test fails, the error message you see is constructed based on the hierarchy of describe blocks. So it would be something like:
MyController $scope .f() should call preventDefault on the given
event