Zoneless Testing - Speaker Deck

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Zoneless Testing Rainer Hahnekamp 6. December 2024

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About Me... https://www.youtube.com/ @RainerHahnekamp https://www.ng-news.com https://github.com/softarc-consulting/sheriff ● Rainer Hahnekamp ANGULARarchitects.io NgRx Team (Trusted Collaborator) ● Developer / Trainer / Speaker @RainerHahnekamp Workshops NgRx • Testing • Spring • Quality

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RainerHahnekamp Why a talk on experimental features??? Critical for some apps Future-proof tests

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RainerHahnekamp Change Detection with zone.js

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RainerHahnekamp Zone.js triggers Change Detection Component Tree DOM Submit Cancel Zone.js Handled DOM Events Asynchronous Tasks

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Component Tree DOM Submit Cancel Change Detection (DOM and Components in Sync)

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Component Tree DOM Submit Cancel Change Detection (Component's value changes)

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...)

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅ ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅ ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅ ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅ ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Detecting Changes...) ✅ ✅ ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Updating DOM) ✅ ✅ ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Updating DOM) ✅ ✅ ✅ ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Updating DOM) ✅ ✅ ✅ ✅ ✅

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Component Tree DOM Submit Cancel Change Detection (Updating DOM) ✅ ✅ ✅ ✅ ✅ ✅

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RainerHahnekamp Change Detection without zone.js

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Component Tree DOM Submit Cancel Zoneless Change Detection Zone.js

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Component Tree DOM Submit Cancel Zoneless Change Detection Zone.js

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Component Tree DOM Submit Cancel Zoneless Change Detection (Change happens)

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Component Tree DOM Submit Cancel Zoneless Change Detection ("Somebody/-thing calls markForCheck()) markForCheck()

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Component Tree DOM Submit Cancel Zoneless Change Detection (markForCheck triggers CD) markForCheck()

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Component Tree DOM Submit Cancel Zoneless Change Detection (Checkend & Done) ✅ ✅ ✅ ✅ ✅ ✅

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RainerHahnekamp Criteria markForCheck Handled DOM Events async Pipe Signal Change manually via markForCheck

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RainerHahnekamp A First Test 1/5

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RainerHahnekamp A First Test 2/5

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RainerHahnekamp A First Test 3a/5 // setup const fixture = TestBed.configureTestingModule({ providers: [ provideExperimentalZonelessChangeDetection(), provideHttpClient(), provideHttpClientTesting() }).createComponent(QuizComponent); fixture.componentRef.setInput('id', 1); fixture.autoDetectChanges(true)

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RainerHahnekamp A First Test 3a/5 // setup const fixture = TestBed.configureTestingModule({ providers: [ provideExperimentalZonelessChangeDetection(), provideHttpClient(), provideHttpClientTesting(), {provide: ComponentFixtureAutoDetect, useValue: false} ], }).createComponent(QuizComponent); fixture.componentRef.setInput('id', 1); fixture.autoDetectChanges(true) Automatic Change Detection enabled in zoneless

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RainerHahnekamp A First Test 3b/5 // setup TestBed.configureTestingModule({ providers: [ provideExperimentalZonelessChangeDetection(), provideHttpClient(), provideHttpClientTesting(), provideRouter( [{ path: 'quiz/:id', component: QuizComponent }], withComponentInputBinding(), ), provideLocationMocks(), ], }); const { fixture } = await RouterTestingHarness.create('/quiz/1');

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RainerHahnekamp A First Test 4/5 // setup... // init const httpClient = TestBed.inject(HttpTestingController); const req = httpClient.expectOne('/holiday/1/quiz'); req.flush(createQuiz(1)); await fixture.whenStable();

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RainerHahnekamp A First Test 5/5 // setup... // init... // execution const question = screen.getByLabelText('question'); const status = screen.getByLabelText('quiz-status'); expect(within(status).getByText('Correct: 0')).toBeTruthy(); expect( within(question).getByText( 'What programming language is Angular written in?', ), ).toBeTruthy(); within(question).getByRole('button', { name: 'TypeScript' }).click(); await fixture.whenStable(); expect(within(status).getByText('Correct: 1')).toBeTruthy();

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RainerHahnekamp Major Pitfalls markForCheck Mutable Property Binding Asynchronous Tasks

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RainerHahnekamp Asynchronous Tasks is a problem? What about fakeAsync() or waitForAsync() 🤨

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RainerHahnekamp Dealing with asynchronous Tasks ComponentFixture ::whenStable

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RainerHahnekamp Dealing with asynchronous Tasks ComponentFixture ::whenStable PendingTasks

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RainerHahnekamp PendingTasks ✅ Ofﬁcial Solution ● (rx)resource() ✅ Required for SSR ✅ Empowers ComponentFixture::whenStable ⛔ Not a good DX ● Overhead ⛔ Timeouts are real ● Slow Tests ⛔ Issues with third-party Libraries

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RainerHahnekamp Dealing with asynchronous Tasks ComponentFixture ::whenStable PendingTasks Stubs & Fakes

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RainerHahnekamp Stub Example // implementation @Injectable({providedIn: 'root'}) export class Clock { setTimeout(fn: () => void, timeout: number) { setTimeout(fn, timeout) } } // stub TestBed.configureTestingModule({ providers: [ // ... { provide: Clock, useValue: { setTimeout: (fn: () => void) => fn() } }, ], });

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RainerHahnekamp Minimal Fake Example export class Clock { readonly #tasks = new Map void>(); schedule(task: () => void, timeout: number) { const timeoutId = window.setTimeout(() => { task(); this.#tasks.delete(timeoutId) }, timeout); this.#tasks.set(timeout, task) } flushAll() { for (const taskId of this.#tasks.keys()) { clearTimeout(taskId) const task = this.#tasks.get(taskId); assertDefined(task); task(); } } }

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RainerHahnekamp Dealing with asynchronous Tasks ComponentFixture ::whenStable PendingTasks Testing Framework Stubs & Fakes

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RainerHahnekamp jasmine.clock it('should show the next button', async () => { const { fixture, question } = await setup(); const clock = jasmine.clock(); clock.install() within(question).getByRole('button', { name: 'TypeScript' }).click(); clock.tick(1000) await fixture.whenStable() });

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RainerHahnekamp Testing Framework Features ● https://github.com/jasmine/jasmine/pull/2042 ● https://github.com/jestjs/jest/pull/15300

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RainerHahnekamp

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RainerHahnekamp

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RainerHahnekamp Dealing with asynchronous Tasks ComponentFixture ::whenStable PendingTasks Testing Framework Cypress CT Stubs & Fakes

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RainerHahnekamp ✅ No Quarrels with ● Change Detection ● DOM Events ● Asynchronous Tasks ✅ Superior DX ⛔ Real Timeout ⛔ Third-Party Library ⛔ No Unit or Service Tests Cypress Component Testing

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RainerHahnekamp Summary ● Zoneless & Testing is easier than you might think ● Careful about asynchronous tasks ● It is still experimental, i.e. up for change ● Always test as close to the real world as possible

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RainerHahnekamp Farewell waitForAsync() and fakeAsync() Embrace ComponentFixture::whenStable