How to unit test Angular.js Controller
1. Write a simple Angular App
Before starting to write the test, we first write a simple calculation App, which will calculate the sum of two numbers.
The code is as follows:
<html>
<head>
<script type="text/javascript" src="https://code.angularjs.org/1.4.0-rc.2/angular.min.js"></script>
</head>
<body>
<!-- This div element corresponds to the CalculatorController we created via the JavaScript-->
<div ng-controller="CalculatorController">
<input ng-model="x" type="number">
<input ng-model="y" type="number">
<strong>{{z}}</strong>
<!-- the value for ngClick maps to the sum function within the controller body -->
<input type="button" ng-click="sum()" value="+">
</div>
</body>
<script type="text/javascript">
// Creates a new module called 'calculatorApp'
angular.module('calculatorApp', []);
// Registers a controller to our module 'calculatorApp'.
angular.module('calculatorApp').controller('CalculatorController', function CalculatorController($scope) {
$scope.z = 0;
$scope.sum = function() {
$scope.z = $scope.x + $scope.y;
};
});
// load the app
angular.element(document).ready(function() {
angular.bootstrap(document, ['calculatorApp']);
});
</script>
</html>
Second, briefly talk about some basic concepts involved:
Create a module
What is angular.module? It is a place for creating and recycling modules. We create a new module called calculatorApp and we add the component to this module.
angular.module('calculatorApp', []);
About the second parameter? The second parameter is required and indicates that we are creating a new module. If our application needs other dependencies, we can pass them ['ngResource', 'ngCookies']. The presence of the second parameter indicates that this is an instance of the module returned by the request.
Conceptually, it is meant to mean something like the following:
* angular.module.createInstance(name, requires); * angular.module.getInstance(name)
However, actually we write it like this:
* angular.module('calculatorApp', []); // i.e. createInstance
* angular.module('calculatorApp'); // i.e. getInstance
More information about module https://docs.angularjs .org/api/ng/function/angular.module
2. Add a controller to the module
Then we add a controller to the angular module example
angular.module('calculatorApp').controller('CalculatorController', function CalculatorController($scope) {
$scope.z = 0;
$scope.sum = function() {
$scope.z = $scope.x + $scope.y;
};
});
The controller is mainly responsible for business logic and view binding , $scope is the direct messenger to the view's controller.
3. Connect elements in the view
In the HTML below, we need to calculate the value in the input, and these are contained in the div of this controller.
<div ng-controller="CalculatorController">
<input ng-model="x" type="number">
<input ng-model="y" type="number">
<strong>{{z}}</strong>
<!-- the value for ngClick maps to the sum function within the controller body -->
<input type="button" ng-click="sum()" value="+">
</div>
Input The value bound to ng-model is the same as that defined on $scope, such as $scope.x. We also bound the $scope.sum method to the button element using ng-click.
3. Add tests
Next we finally get to our topic, add some unit tests to the controller. We ignore the html part of the code and focus mainly on the controller code.
angular.module('calculatorApp').controller('CalculatorController', function CalculatorController($scope) {
$scope.z = 0;
$scope.sum = function() {
$scope.z = $scope.x + $scope.y;
};
});
In order to test the controller, we need to mention the following points? + How to create a controller instance + How to get/set the properties of an object + How to call functions in $scope
describe('calculator', function () {
beforeEach(angular.mock.module('calculatorApp'));
var $controller;
beforeEach(angular.mock.inject(function(_$controller_){
$controller = _$controller_;
}));
describe('sum', function () {
it('1 + 1 should equal 2', function () {
var $scope = {};
var controller = $controller('CalculatorController', { $scope: $scope });
$scope.x = 1;
$scope.y = 2;
$scope.sum();
expect($scope.z).toBe(3);
});
});
});
Before we start, we need to introduce ngMock. We add angular.mock
, ngMock to the test code Modules provide a mechanism for unit testing of virtual services.
4. How to get the controller instance
Using ngMock we can register a calculator app instance.
beforeEach(angular.mock.module('calculatorApp'));
Once the calculatorApp is initialized, we can use the inject function, which can solve the controller reference problem.
beforeEach(angular.mock.inject(function(_$controller_) {
$controller = _$controller_;
}));
Once the app is loaded, we use the inject function, and the $controller service can obtain an instance of CalculatorController.
var controller = $controller('CalculatorController', { $scope: $scope });
5. How to get/set the attributes of an object
In the previous code, we can already get an instance of a controller. The second parameter in the brackets is actually the controller itself. Our controller only has A parameter $scope object
function CalculatorController($scope) { ... }
In our test $scope represents a simple JavaScript object.
var $scope = {};
var controller = $controller('CalculatorController', { $scope: $scope });
// set some properties on the scope object
$scope.x = 1;
$scope.y = 2;
We set the values of x and y to simulate what is shown in the gif just now. We agree that we can also read the properties in the object, just like the assertion in the following test:
expect($scope.z).toBe(3);
6. How to call the functions in $scope
The last thing is how we simulate the user’s click , just like what we use in most JS, it is actually just a simple call to the function,
$scope.sum();
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