isabella232 / intern-angular

Intern helper library for Angular 2+

Intern + Angular

This is a test project to demonstrate using Intern with Angular 4+. It contains all of the specs from Angular's test guide as well as some extras. Specs have been reformatted and converted to using Intern best practices as outlined below.

Get started

Clone the repo

git clone https://github.com/bryanforbes/intern-angular
cd intern-angular

Install npm packages

Install the npm packages described in the package.json and verify that it works:

npm install
npm start

The npm start command builds (compiles TypeScript and copies assets) the application into dist/, watches for changes to the source files, and runs lite-server on port 3000.

Shut it down manually with Ctrl-C.

npm scripts

These are the most useful commands defined in package.json:

• npm start - runs the TypeScript compiler, asset copier, and a server at the same time, all three in "watch mode".
• npm run build - runs the TypeScript compiler and asset copier once.
• npm run build:watch - runs the TypeScript compiler and asset copier in "watch mode"; when changes occur to source files, they will be recompiled or copied into dist/.
• npm run lint - runs tslint on the project files.
• npm run serve - runs lite-server.

These are the test-related scripts:

• npm test - builds the application and runs Intern tests (both unit and functional) one time.
• npm run ci - cleans, lints, and builds the application and runs Intern tests (both unit and functional) one time.

Techniques

Because Intern seamlessly handles asynchronous testing, there is no reason to use async, fakeAsync, or tick from @angular/core/testing. Furthermore, because TypeScript introduced downlevel asynchronous function support in version 2.1, the use of async and await has been leveraged to write these tests.

Intern bdd interfaces

The first change made to all spec files was to assign the describe, it, beforeEach, and expect functions from the Intern plugins:

const { describe, it, beforeEach } = intern.getPlugin('interface.bdd');
const { expect } = intern.getPlugin('chai');

Most of these interfaces behave similarly to jasmine or mocha with a couple of exceptions. First, before, after, beforeEach, afterEach, and it can all take a function that returns a promise or is defined with async and Intern will wait until that promise has resolved before proceeding to the next test/lifecycle function.

It should be noted that Intern currently (alpha.9) does not wait for a promise to resolve if there are multiple of the same lifecycle functions in one describe block. For instance, this is quite common to see in Angular tests:

beforeEach(async(() => {
	TestBed.configureTestingModule({
		declarations: [ DashboardHeroComponent ],
	})
	.compileComponents();
}));

beforeEach(() => {
	fixture = TestBed.createComponent(DashboardHeroComponent);
	comp    = fixture.componentInstance;
	heroEl  = fixture.debugElement.query(By.css('.hero'));
});

Using async and await, this can be easily rewritten into a single function with Intern:

beforeEach(async () => {
	await TestBed.configureTestingModule({
		declarations: [ DashboardHeroComponent ],
	})
	.compileComponents();

	fixture = TestBed.createComponent(DashboardHeroComponent);
	comp    = fixture.componentInstance;
	heroEl  = fixture.debugElement.query(By.css('.hero'));
});

Since Intern comes with Chai bundled, many of the expectations had to be rewritten. Most of these were simply changing .toBe() to .to.equal() or toMatch() to to.match().

Another change was from using jasmine's spyOn() to Sinon.JS's spy() and stub() as well as sinon-chai to add expectations for stubs and spies to expect().

Asynchronous functions

Similar to the lifecycle functions, any invocation of it that used Angular's async() or fakeAsync() was rewritten to use an asynchronous function. For instance:

it('should show quote after getQuote promise (async)', async(() => {
	fixture.detectChanges();

	fixture.whenStable().then(() => { // wait for async getQuote
		fixture.detectChanges();        // update view with quote
		expect(el.textContent).toBe(testQuote);
	});
}));

it('should select hero on click', fakeAsync(() => {
	const expectedHero = HEROES[1];
	const li = page.heroRows[1];
	li.dispatchEvent(newEvent('click'));
	tick();
	// `.toEqual` because selectedHero is clone of expectedHero; see FakeHeroService
	expect(comp.selectedHero).toEqual(expectedHero);
}));

These can be easily rewritten to the following:

it('should show quote after getQuote promise', async () => {
	fixture.detectChanges();

	await fixture.whenStable(); // wait for async getQuote
	fixture.detectChanges();    // update view with quote
	expect(el.textContent).to.equal(testQuote);
});

it('should select hero on click', async () => {
	const expectedHero = HEROES[1];
	const li = page.heroRows[1];
	li.dispatchEvent(newEvent('click'));
	await comp.heroes; // the promise returned from the service
	expect(comp.selectedHero).to.deep.equal(expectedHero);
});