Unit Testing Basics
Unit tests are generally used to test a small piece of code and ensure that it is doing what was intended. Unlike integration tests, they are narrow in scope and do not require the Ember application to be running.
As it is the basic object type in Ember, being able to test a simple
Ember.Object sets the foundation for testing more specific parts of your
Ember application such as controllers, components, etc. Testing an Ember.Object
is as simple as creating an instance of the object, setting its state, and
running assertions against the object. By way of example lets look at a few
common cases.
Testing Computed Properties
Let's start by looking at an object that has a computedFoo computed property
based on a foo property.
App.SomeThing = Ember.Object.extend({
foo: 'bar',
computedFoo: function(){
return 'computed ' + this.get('foo');
}.property('foo')
});
Within the test we'll create an instance, update the foo property (which
should trigger the computed property), and assert that the logic in our
computed property is working correctly.
module('Unit: SomeThing');
test('computedFoo correctly concats foo', function() {
var someThing = App.SomeThing.create();
someThing.set('foo', 'baz');
equal(someThing.get('computedFoo'), 'computed baz');
});
Live Example
Testing Object Methods
Next let's look at testing logic found within an object's method. In this case
the testMethod method alters some internal state of the object (by updating
the foo property).
App.SomeThing = Ember.Object.extend({
foo: 'bar',
testMethod: function() {
this.set('foo', 'baz');
}
});
To test it, we create an instance of our class SomeThing as defined above,
call the testMethod method and assert that the internal state is correct as a
result of the method call.
module('Unit: SomeThing');
test('calling testMethod updates foo', function() {
var someThing = App.SomeThing.create();
someThing.testMethod();
equal(someThing.get('foo'), 'baz');
});
Live Example
Unit Testing Basics: Method Side Effects
In the event the object's method returns a value you can simply assert that the
return value is calculated correctly. Suppose our object has a calc method
that returns a value based on some internal state.
App.SomeThing = Ember.Object.extend({
count: 0,
calc: function() {
this.incrementProperty('count');
return 'count: ' + this.get('count');
}
});
The test would call the calc method and assert it gets back the correct value.
module('Unit: SomeThing');
test('testMethod returns incremented count', function() {
var someThing = App.SomeThing.create();
equal(someThing.calc(), 'count: 1');
equal(someThing.calc(), 'count: 2');
});
Live Example
Testing Observers
Suppose we have an object that has a property and a method observing that property.
App.SomeThing = Ember.Object.extend({
foo: 'bar',
other: 'no',
doSomething: function(){
this.set('other', 'yes');
}.observes('foo')
});
In order to test the doSomething method we create an instance of SomeThing,
update the observed property (foo), and assert that the expected effects are present.
module('Unit: SomeThing');
test('doSomething observer sets other prop', function() {
var someThing = App.SomeThing.create();
someThing.set('foo', 'baz');
equal(someThing.get('other'), 'yes');
});