@ngneat/spectator
Advanced tools
A Powerful Tool to Simplify Your Angular Tests
Spectator helps you get rid of all the boilerplate grunt work, leaving you with readable, sleek and streamlined unit tests.
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npm install @ngneat/spectator --save-dev
yarn add @ngneat/spectator --dev
Create a component factory by using the createComponentFactory() function, passing the component class that you want to test.
The createComponentFactory() returns a function that will create a fresh component in each it block:
import { Spectator, createComponentFactory } from '@ngneat/spectator';
import { ButtonComponent } from './button.component';
describe('ButtonComponent', () => {
let spectator: Spectator<ButtonComponent>;
const createComponent = createComponentFactory(ButtonComponent);
beforeEach(() => spectator = createComponent());
it('should have a success class by default', () => {
expect(spectator.query('button')).toHaveClass('success');
});
it('should set the class name according to the [className] input', () => {
spectator.setInput('className', 'danger');
expect(spectator.query('button')).toHaveClass('danger');
expect(spectator.query('button')).not.toHaveClass('success');
});
});
The createComponentFactory function can optionally take the following options which extends the basic Angular Testing Module options:
const createComponent = createComponentFactory({
component: ButtonComponent,
imports: [],
providers: [],
declarations: [],
entryComponents: [],
componentProviders: [], // Override the component's providers
componentViewProviders: [], // Override the component's view providers
overrideModules: [], // Override modules
overrideComponents: [], // Override components in case of testing standalone component
overrideDirectives: [], // Override directives in case of testing standalone directive
overridePipes: [], // Override pipes in case of testing standalone pipe
mocks: [], // Providers that will automatically be mocked
componentMocks: [], // Component providers that will automatically be mocked
componentViewProvidersMocks: [], // Component view providers that will be automatically mocked
detectChanges: false, // Defaults to true
declareComponent: false, // Defaults to true
disableAnimations: false, // Defaults to true
shallow: true, // Defaults to false
deferBlockBehavior: DeferBlockBehavior // Defaults to DeferBlockBehavior.Playthrough
});
The createComponent() function optionally takes the following options:
it('should...', () => {
spectator = createComponent({
// The component inputs
props: {
title: 'Click'
},
// Override the component's providers
// Note that you must declare it once in `createComponentFactory`
providers: [],
// Whether to run change detection (defaults to true)
detectChanges: false
});
expect(spectator.query('button')).toHaveText('Click');
});
By providing overrideComponents options in scope of our createComponent() function we can define the way of overriding standalone component and it's dependencies
@Component({
selector: `app-standalone-with-import`,
template: `<div id="standalone">Standalone component with import!</div>
<app-standalone-with-dependency></app-standalone-with-dependency>`,
imports: [StandaloneComponentWithDependency],
standalone: true,
})
export class StandaloneWithImportsComponent {}
@Component({
selector: `app-standalone-with-dependency`,
template: `<div id="standaloneWithDependency">Standalone component with dependency!</div>`,
standalone: true,
})
export class StandaloneComponentWithDependency {
constructor(public query: QueryService) {}
}
@Component({
selector: `app-standalone-with-dependency`,
template: `<div id="standaloneWithDependency">Standalone component with override dependency!</div>`,
standalone: true,
})
export class MockStandaloneComponentWithDependency {
constructor() {}
}
it('should...', () => {
const spectator = createHostFactory({
component: StandaloneWithImportsComponent,
template: `<div><app-standalone-with-import></app-standalone-with-import></div>`,
overrideComponents: [
[
StandaloneWithImportsComponent,
{
remove: { imports: [StandaloneComponentWithDependency] },
add: { imports: [MockStandaloneComponentWithDependency] },
},
],
],
});
expect(host.query('#standalone')).toContainText('Standalone component with import!');
expect(host.query('#standaloneWithDependency')).toContainText('Standalone component with override dependency!');
});
The createComponent() method returns an instance of Spectator which exposes the following API:
fixture - The tested component's fixture
component - The tested component's instance
element - The tested component's native element
debugElement - The tested fixture's debug element
flushEffects() - Provides a wrapper for TestBed.flushEffects()
runInInjectionContext() - Provides a wrapper for TestBed.runInInjectionContext()
inject() - Provides a wrapper for TestBed.inject():
const service = spectator.inject(QueryService);
const fromComponentInjector = true;
const service = spectator.inject(QueryService, fromComponentInjector);
detectChanges() - Runs detectChanges on the tested element/host:spectator.detectChanges();
detectComponentChanges() - Runs detectChanges on the tested component ( not on the host ).
You'll need this method in rare cases when using a host and the tested component is onPush, and you want to force it to run a change detection cycle.spectator.detectComponentChanges();
setInput() - Changes the value of an @Input() of the tested component.
Method runs ngOnChanges with SimpleChanges manually if it exists.it('should...', () => {
spectator.setInput('className', 'danger');
spectator.setInput({
className: 'danger'
});
});
output - Returns an Observable @Output() of the tested component:it('should emit the $event on click', () => {
let output;
spectator.output('click').subscribe(result => (output = result));
spectator.component.onClick({ type: 'click' });
expect(output).toEqual({ type: 'click' });
});
tick(millis?: number) - Run the fakeAsync tick() function and call detectChanges():it('should work with tick', fakeAsync(() => {
spectator = createComponent(ZippyComponent);
spectator.component.update();
expect(spectator.component.updatedAsync).toBeFalsy();
spectator.tick(6000);
expect(spectator.component.updatedAsync).not.toBeFalsy();
}))
Each one of the events can accept a SpectatorElement which can be one of the following:
type SpectatorElement = string | Element | DebugElement | ElementRef | Window | Document | DOMSelector;
If not provided, the default element will be the host element of the component under test.
click() - Triggers a click event:spectator.click(SpectatorElement);
spectator.click(byText('Element'));
blur() - Triggers a blur event:spectator.blur(SpectatorElement);
spectator.blur(byText('Element'));
Note that if using the jest framework, blur() only works if the element is focused. Details.
focus() - Triggers a focus event:spectator.focus(SpectatorElement);
spectator.focus(byText('Element'));
typeInElement() - Simulating the user typing:spectator.typeInElement(value, SpectatorElement);
spectator.typeInElement(value, byText('Element'));
dispatchMouseEvent() - Triggers a mouse event:spectator.dispatchMouseEvent(SpectatorElement, 'mouseout');
spectator.dispatchMouseEvent(SpectatorElement, 'mouseout'), x, y, event);
spectator.dispatchMouseEvent(byText('Element'), 'mouseout');
spectator.dispatchMouseEvent(byText('Element'), 'mouseout', x, y, event);
dispatchKeyboardEvent() - Triggers a keyboard event:spectator.dispatchKeyboardEvent(SpectatorElement, 'keyup', 'Escape');
spectator.dispatchKeyboardEvent(SpectatorElement, 'keyup', { key: 'Escape', keyCode: 27 })
spectator.dispatchKeyboardEvent(byText('Element'), 'keyup', 'Escape');
spectator.dispatchKeyboardEvent(byText('Element'), 'keyup', { key: 'Escape', keyCode: 27 })
dispatchTouchEvent() - Triggers a touch event:spectator.dispatchTouchEvent(SpectatorElement, type, x, y);
spectator.dispatchTouchEvent(byText('Element'), type, x, y);
You can trigger custom events (@Output() of child components) using the following method:
spectator.triggerEventHandler(MyChildComponent, 'myCustomEvent', 'eventValue');
spectator.triggerEventHandler(MyChildComponent, 'myCustomEvent', 'eventValue', { root: true});
spectator.triggerEventHandler('app-child-component', 'myCustomEvent', 'eventValue');
spectator.triggerEventHandler('app-child-component', 'myCustomEvent', 'eventValue', { root: true});
In case you want to test events independently of any template (e.g. in presenter services) you can fallback on the underlying event creators. They are basically providing the same signature without the preceding element.
const keyboardEvent = createKeyboardEvent('keyup', 'ArrowDown'/*, targetElement */);
const mouseEvent = createMouseEvent('mouseout');
const touchEvent = createTouchEvent('touchmove');
const fakeEvent = createFakeEvent('input');
spectator.keyboard.pressEnter();
spectator.keyboard.pressEscape();
spectator.keyboard.pressTab();
spectator.keyboard.pressBackspace();
spectator.keyboard.pressKey('a');
spectator.keyboard.pressKey('ctrl.a');
spectator.keyboard.pressKey('ctrl.shift.a');
spectator.mouse.contextmenu('.selector');
spectator.mouse.dblclick('.selector');
Note that each one of the above methods will also run detectChanges().
The Spectator API includes convenient methods for querying the DOM as part of a test: query, queryAll, queryLast , queryHost and queryHostAll. All query methods are polymorphic and allow you to query using any of the following techniques.
Pass a string selector (in the same style as you would when using jQuery or document.querySelector) to query for elements that match that path in the DOM. This method for querying is equivalent to Angular's By.css predicate. Note that native HTML elements will be returned. For example:
// Returns a single HTMLElement
spectator.query('div > ul.nav li:first-child');
// Returns an array of all matching HTMLElements
spectator.queryAll('div > ul.nav li');
// Query from the document context
spectator.query('div', { root: true });
spectator.query('app-child', { read: ChildServiceService });
Pass a type (such as a component, directive or provider class) to query for instances of that type in the DOM. This is equivalent to Angular's By.directive predicate. You can optionally pass in a second parameter to read a specific injection token from the matching elements' injectors. For example:
// Returns a single instance of MyComponent (if present)
spectator.query(MyComponent);
// Returns the instance of `SomeService` found in the instance of `MyComponent` that exists in the DOM (if present)
spectator.query(MyComponent, { read: SomeService });
spectator.query(MyComponent, { read: ElementRef });
host.queryLast(ChildComponent);
host.queryAll(ChildComponent);
Spectator allows you to query for elements using selectors inspired by dom-testing-library. The available selectors are:
spectator.query(byPlaceholder('Please enter your email address'));
spectator.query(byValue('By value'));
spectator.query(byTitle('By title'));
spectator.query(byAltText('By alt text'));
spectator.query(byLabel('By label'));
spectator.query(byText('By text'));
spectator.query(byText('By text', {selector: '#some .selector'}));
spectator.query(byTextContent('By text content', {selector: '#some .selector'}));
spectator.query(byRole('checkbox', { checked: true }));
The difference between byText and byTextContent is that the former doesn't match text inside a nested elements.
For example, in this following HTML byText('foobar', {selector: 'div'}) won't match the following div, but byTextContent will:
<div>
<span>foo</span>
<span>bar</span>
</div>
Spectator allows you to query for nested elements within a parent element. This is useful when you have multiple instances of the same component on the page and you want to query for children within a specific one. The parent selector is a string selector that is used to find the parent element. The parent selector is passed as the second parameter to the query methods. For example:
spectator.query(ChildComponent, { parentSelector: '#parent-component-1' });
spectator.queryAll(ChildComponent, { parentSelector: '#parent-component-1' });
Spectator allows you to test <select></select> elements easily, and supports multi select.
Example:
it('should set the correct options on multi select', () => {
const select = spectator.query('#test-multi-select') as HTMLSelectElement;
spectator.selectOption(select, ['1', '2']);
expect(select).toHaveSelectedOptions(['1', '2']);
});
it('should set the correct option on standard select', () => {
const select = spectator.query('#test-single-select') as HTMLSelectElement;
spectator.selectOption(select, '1');
expect(select).toHaveSelectedOptions('1');
});
It also allows you to check if your change event handler is acting correctly for each item selected. You can disable this if you need to pre set choices without dispatching the change event.
API:
spectator.selectOption(selectElement: HTMLSelectElement, options: string | string[] | HTMLOptionElement | HTMLOptionElement[], config: { emitEvents: boolean } = { emitEvents: true });
Example:
it('should dispatch correct number of change events', () => {
const onChangeSpy = spyOn(spectator.component, 'handleChange');
const select = spectator.query('#test-onchange-select') as HTMLSelectElement;
spectator.selectOption(select, ['1', '2'], { emitEvents: true});
expect(select).toHaveSelectedOptions(['1', '2']);
expect(onChangeSpy).toHaveBeenCalledTimes(2);
});
it('should not dispatch correct number of change events', () => {
const onChangeSpy = spyOn(spectator.component, 'handleChange');
const select = spectator.query('#test-onchange-select') as HTMLSelectElement;
spectator.selectOption(select, ['1', '2'], { emitEvents: false});
expect(select).toHaveSelectedOptions(['1', '2']);
expect(onChangeSpy).not.toHaveBeenCalledTimes(2);
});
You can also pass HTMLOptionElement(s) as arguments to selectOption and the toHaveSelectedOptions matcher. This is particularly useful when you are using [ngValue] binding on the <option>:
it('should set the correct option on single select when passing the element', () => {
const select = spectator.query('#test-single-select-element') as HTMLSelectElement;
spectator.selectOption(select, spectator.query(byText('Two')) as HTMLOptionElement);
expect(select).toHaveSelectedOptions(spectator.query(byText('Two')) as HTMLOptionElement);
});
If you need to mock components, you can use the ng-mocks library. Instead of using CUSTOM_ELEMENTS_SCHEMA,which might hide some issues and won't help you to set inputs, outputs, etc., ng-mocks will auto mock the inputs, outputs, etc. for you.
Example:
import { createHostFactory } from '@ngneat/spectator';
import { MockComponent } from 'ng-mocks';
import { FooComponent } from './path/to/foo.component';
const createHost = createHostFactory({
component: YourComponentToTest,
declarations: [
MockComponent(FooComponent)
]
});
Components (or Directives) that are declared in their own module can be tested by defining the component module in the imports list of the component factory together with the component. For example:
const createComponent = createComponentFactory({
component: ButtonComponent,
imports: [ButtonComponentModule],
});
When used like this, however, Spectator internally adds the component ButtonComponent to the declarations of the internally created new module. Hence, you will see the following error:
Type ButtonComponent is part of the declarations of 2 modules [...]
It is possible to tell Spectator not to add the component to the declarations of the internal module and, instead, use the explicitly defined module as is. Simply set the declareComponent property of the factory options to false:
const createComponent = createComponentFactory({
component: ButtonComponent,
imports: [ButtonComponentModule],
declareComponent: false,
});
When using createDirectiveFactory set the declareDirective property of the factory options to false:
const createDirective = createDirectiveFactory({
component: HighlightComponent,
imports: [HighlightComponentModule],
declareDirective: false,
});
The Spectator provides a convenient API to access the deferrable views (@defer {}).
Access the desired defer block using the spectator.deferBlock(optionalIndex) method. The optionalIndex parameter is optional and allows you to specify the index of the defer block you want to access.
spectator.deferBlock().spectator.deferBlock(1) accesses the second block (zero-based indexing).The spectator.deferBlock(optionalIndex) returns four methods for rendering different states of the specified defer block:
renderComplete() - Renders the complete state of the defer block.renderPlaceholder() - Renders the placeholder state of the defer block.renderLoading() - Renders the loading state of the defer block.renderError() - Renders the error state of the defer block.Example:
@Component({
selector: 'app-cmp',
template: `
@defer (on viewport) {
<div>Complete state of the first defer block</div> <!--Parent Complete State-->
} @placeholder {
<div>Placeholder</div>
}
`,
})
class DummyComponent {}
const createComponent = createComponentFactory({
component: DummyComponent,
deferBlockBehavior: DeferBlockBehavior.Manual,
});
it('should render the complete state', async () => {
// Arrange
const spectator = createComponent();
// Act
await spectator.deferBlock().renderComplete();
// Assert
expect(spectator.element.outerHTML).toContain('first defer block');
});
To access states within nested defer blocks, call the deferBlock method chaining from the returned block state method.
Example: Accessing the nested complete state:
// Assuming `spectator.deferBlock(0).renderComplete()` renders the complete state of the parent defer block
const parentCompleteState = await spectator.deferBlock().renderComplete();
// Access the nested complete state of the parent defer block
const nestedCompleteState = await parentCompleteState.renderComplete().deferBlock();
Complete Example:
@Component({
selector: 'app-cmp',
template: `
@defer (on viewport) {
<div>Complete state of the first defer block</div> <!--Parent Complete State-->
@defer {
<div>Complete state of the nested defer block</div> <!--Nested Complete State-->
}
} @placeholder {
<div>Placeholder</div>
}
`,
})
class DummyComponent {}
const createComponent = createComponentFactory({
component: DummyComponent,
deferBlockBehavior: DeferBlockBehavior.Manual,
});
it('should render the first nested complete state', async () => {
// Arrange
const spectator = createComponent();
// Act
// Renders the parent complete state
const parentCompleteState = await spectator.deferBlock().renderComplete();
// Renders the nested complete state
await parentCompleteState.deferBlock().renderComplete();
// Assert
expect(spectator.element.outerHTML).toContain('nested defer block');
});
Testing a component with a host component is a more elegant and powerful technique to test your component. It basically gives you the ability to write your tests in the same way that you write your code. Let's see it in action:
import { createHostFactory, SpectatorHost } from '@ngneat/spectator';
describe('ZippyComponent', () => {
let spectator: SpectatorHost<ZippyComponent>;
const createHost = createHostFactory(ZippyComponent);
it('should display the title from host property', () => {
spectator = createHost(`<zippy [title]="title"></zippy>`, {
hostProps: {
title: 'Spectator is Awesome'
}
});
expect(spectator.query('.zippy__title')).toHaveText('Spectator is Awesome');
});
it('should display the "Close" word if open', () => {
spectator = createHost(`<zippy title="Zippy title">Zippy content</zippy>`);
spectator.click('.zippy__title');
expect(spectator.query('.arrow')).toHaveText('Close');
expect(spectator.query('.arrow')).not.toHaveText('Open');
});
});
The host method returns an instance of SpectatorHost which extends Spectator with the following additional API:
hostFixture - The host's fixturehostComponent - The host's component instancehostElement - The host's native elementhostDebugElement - The host's fixture debug elementsetHostInput - Changes the value of an @Input() of the host componentqueryHost - Read more about querying in SpectatorqueryHostAll - Read more about querying in SpectatorSetting inputs directly on a component using setInput or props is not possible when testing with a host component.
Inputs should be set through hostProps or setHostInput instead, and passed through to your component in the template.
Sometimes it's helpful to pass your own host implementation. We can pass a custom host component to the createHostFactory() that will replace the default one:
@Component({ selector: 'custom-host', template: '' })
class CustomHostComponent {
title = 'Custom HostComponent';
}
describe('With Custom Host Component', function () {
let spectator: SpectatorHost<ZippyComponent, CustomHostComponent>;
const createHost = createHostFactory({
component: ZippyComponent,
host: CustomHostComponent
});
it('should display the host component title', () => {
spectator = createHost(`<zippy [title]="title"></zippy>`);
expect(spectator.query('.zippy__title')).toHaveText('Custom HostComponent');
});
});
For components which use routing, there is a special factory available that extends the default one, and provides a stubbed ActivatedRoute so that you can configure additional routing options.
describe('ProductDetailsComponent', () => {
let spectator: SpectatorRouting<ProductDetailsComponent>;
const createComponent = createRoutingFactory({
component: ProductDetailsComponent,
params: { productId: '3' },
data: { title: 'Some title' }
});
beforeEach(() => spectator = createComponent());
it('should display route data title', () => {
expect(spectator.query('.title')).toHaveText('Some title');
});
it('should react to route changes', () => {
spectator.setRouteParam('productId', '5');
// your test here...
});
});
The SpectatorRouting API includes convenient methods for updating the current route:
interface SpectatorRouting<C> extends Spectator<C> {
/**
* Simulates a route navigation by updating the Params, QueryParams and Data observable streams.
*/
triggerNavigation(options?: RouteOptions): void;
/**
* Updates the route params and triggers a route navigation.
*/
setRouteParam(name: string, value: string): void;
/**
* Updates the route query params and triggers a route navigation.
*/
setRouteQueryParam(name: string, value: string): void;
/**
* Updates the route data and triggers a route navigation.
*/
setRouteData(name: string, value: any): void;
/**
* Updates the route fragment and triggers a route navigation.
*/
setRouteFragment(fragment: string | null): void;
/**
* Updates the route url and triggers a route navigation.
*/
setRouteUrl(url: UrlSegment[]): void;
}
RouterTestingModuleIf you set the stubsEnabled option to false, you can pass a real routing configuration
and setup an integration test using the RouterTestingModule from Angular.
Note that this requires promises to resolve. One way to deal with this, is by making your test async:
describe('Routing integration test', () => {
const createComponent = createRoutingFactory({
component: MyComponent,
declarations: [OtherComponent],
stubsEnabled: false,
routes: [
{
path: '',
component: MyComponent
},
{
path: 'foo',
component: OtherComponent
}
]
});
it('should navigate away using router link', async () => {
const spectator = createComponent();
// wait for promises to resolve...
await spectator.fixture.whenStable();
// test the current route by asserting the location
expect(spectator.inject(Location).path()).toBe('/');
// click on a router link
spectator.click('.link-1');
// don't forget to wait for promises to resolve...
await spectator.fixture.whenStable();
// test the new route by asserting the location
expect(spectator.inject(Location).path()).toBe('/foo');
});
});
The createRoutesFactory function can take the following options, on top of the default Spectator options:
params: initial params to use in ActivatedRoute stubqueryParams: initial query params to use in ActivatedRoute stubdata: initial data to use in ActivatedRoute stubfragment: initial fragment to use in ActivatedRoute stuburl: initial URL segments to use in ActivatedRoute stubroot: the value for root for the ActivatedRoute stubparent: the value for parent for the ActivatedRoute stubchildren: the value for children for the ActivatedRoute stubfirstChild: the value for firstChild for the ActivatedRoute stubstubsEnabled (default: true): enables the ActivatedRoute stub, if set to false it uses RouterTestingModule insteadroutes: if stubsEnabled is set to false, you can pass a Routes configuration for RouterTestingModuleThere is a special test factory for testing directives. Let's say we have the following directive:
@Directive({ selector: '[highlight]' })
export class HighlightDirective {
@HostBinding('style.background-color') backgroundColor : string;
@HostListener('mouseover')
onHover() {
this.backgroundColor = '#000000';
}
@HostListener('mouseout')
onLeave() {
this.backgroundColor = '#ffffff';
}
}
Let's see how we can test directives easily with Spectator:
describe('HighlightDirective', () => {
let spectator: SpectatorDirective<HighlightDirective>;
const createDirective = createDirectiveFactory(HighlightDirective);
beforeEach(() => {
spectator = createDirective(`<div highlight>Testing Highlight Directive</div>`);
});
it('should change the background color', () => {
spectator.dispatchMouseEvent(spectator.element, 'mouseover');
expect(spectator.element).toHaveStyle({
backgroundColor: 'rgba(0,0,0, 0.1)'
});
spectator.dispatchMouseEvent(spectator.element, 'mouseout');
expect(spectator.element).toHaveStyle({
backgroundColor: '#fff'
});
});
it('should get the instance', () => {
const instance = spectator.directive;
expect(instance).toBeDefined();
});
});
Setting inputs directly on a directive using setInput or props is not possible.
Inputs should be set through hostProps or setHostInput instead, and passed through to your directive in the template.
The following example shows how to test a service with Spectator:
import { createServiceFactory, SpectatorService } from '@ngneat/spectator';
import { AuthService } from 'auth.service.ts';
describe('AuthService', () => {
let spectator: SpectatorService<AuthService>;
const createService = createServiceFactory(AuthService);
beforeEach(() => spectator = createService());
it('should not be logged in', () => {
expect(spectator.service.isLoggedIn()).toBeFalsy();
});
});
The createService() function returns SpectatorService with the following properties:
service - Get an instance of the serviceinject() - A proxy for Angular TestBed.inject()flushEffects() - A proxy for Angular TestBed.flushEffects()runInInjectionContext() - A proxy for Angular TestBed.runInInjectionContext()It's also possible to pass an object with options. For example, when testing a service you often want to mock its dependencies, as we focus on the service being tested.
For example:
@Injectable()
export class AuthService {
constructor( private dateService: DateService ) {}
isLoggedIn() {
if( this.dateService.isExpired('timestamp') ) {
return false;
}
return true;
}
}
In this case we can mock the DateService dependency.
import { createServiceFactory, SpectatorService } from '@ngneat/spectator';
import { AuthService } from 'auth.service.ts';
describe('AuthService', () => {
let spectator: SpectatorService<AuthService>;
const createService = createServiceFactory({
service: AuthService,
providers: [],
entryComponents: [],
mocks: [DateService]
});
beforeEach(() => spectator = createService());
it('should be logged in', () => {
const dateService = spectator.inject(DateService);
dateService.isExpired.and.returnValue(false);
expect(spectator.service.isLoggedIn()).toBeTruthy();
});
});
The following example shows how to test a pipe with Spectator:
import { SpectatorPipe, createPipeFactory } from '@ngneat/spectator';
import { StatsService } from './stats.service';
import { SumPipe } from './sum.pipe';
describe('SumPipe', () => {
let spectator: SpectatorPipe<SumPipe>;
const createPipe = createPipeFactory(SumPipe);
it('should sum up the given list of numbers (template)', () => {
spectator = createPipe(`{{ [1, 2, 3] | sum }}`);
expect(spectator.element).toHaveText('6');
});
it('should sum up the given list of numbers (prop)', () => {
spectator = createPipe(`{{ prop | sum }}`, {
hostProps: {
prop: [1, 2, 3]
}
});
expect(spectator.element).toHaveText('6');
});
it('should delegate the summation to the service', () => {
const sum = () => 42;
const provider = { provide: StatsService, useValue: { sum } };
spectator = createPipe(`{{ prop | sum }}`, {
hostProps: {
prop: [2, 40]
},
providers: [provider]
});
expect(spectator.element).toHaveText('42');
});
});
The createPipe() function returns SpectatorPipe with the following properties:
hostComponent - Instance of the host componentdebugElement - The debug element of the fixture around the host componentelement - The native element of the host componentdetectChanges() - A proxy for Angular TestBed.fixture.detectChanges()inject() - A proxy for Angular TestBed.inject()flushEffects() - A proxy for Angular TestBed.flushEffects()runInInjectionContext() - A proxy for Angular TestBed.runInInjectionContext()Setting inputs directly on a pipe using setInput or props is not possible.
Inputs should be set through hostProps or setHostInput instead, and passed through to your pipe in the template.
The following example illustrates how to test a pipe using a custom host component:
import { Component, Input } from '@angular/core';
import { SpectatorPipe, createPipeFactory } from '@ngneat/spectator';
import { AveragePipe } from './average.pipe';
import { StatsService } from './stats.service';
@Component({
template: `<div>{{ prop | avg }}</div>`
})
class CustomHostComponent {
@Input() public prop: number[] = [1, 2, 3];
}
describe('AveragePipe', () => {
let spectator: SpectatorPipe<AveragePipe>;
const createPipe = createPipeFactory({
pipe: AveragePipe,
host: CustomHostComponent
});
it('should compute the average of a given list of numbers', () => {
spectator = createPipe();
expect(spectator.element).toHaveText('2');
});
it('should result to 0 when list of numbers is empty', () => {
spectator = createPipe({
hostProps: {
prop: []
}
});
expect(spectator.element).toHaveText('0');
});
it('should delegate the calculation to the service', () => {
const avg = () => 42;
const provider = { provide: StatsService, useValue: { avg } };
spectator = createPipe({
providers: [provider]
});
expect(spectator.element).toHaveText('42');
});
});
Every Spectator instance supports testing DI Function by passing them to runInInjectionContext() function. There is a dedicated test factory that simplifies such testing by eliminating the need to pass some arbitrary Angular class amongst other factory options. Let's say we have a following function that uses the http module to fetch users:
import { HttpClient } from '@angular/common/http';
import { inject } from '@angular/core';
function getUsers() {
return inject(HttpClient).get<User[]>('users');
}
Let's see how we can test DI Function easily with Spectator:
import { HttpTestingController, provideHttpClientTesting } from '@angular/common/http/testing';
import { createInjectionContextFactory, SpectatorInjectionContext } from '@ngneat/spectator';
function getUsers() {
return inject(HttpClient).get<User[]>('users');
}
describe('Users', () => {
let spectator: SpectatorInjectionContext;
const createContext = createInjectionContextFactory({ providers: [provideHttpClientTesting()] });
it('should fetch users', () => {
spectator = createContext();
const controller = spectator.inject(HttpTestingController);
spectator.runInInjectionContext(getUsers).subscribe((users) => {
expect(users.length).toBe(1);
});
controller.expectOne('users').flush([{ id: 1 }]);
});
});
The createContext() function returns SpectatorInjectionContext with the following properties:
inject() - A proxy for Angular TestBed.inject()flushEffects() - A proxy for Angular TestBed.flushEffects()runInInjectionContext() - A proxy for Angular TestBed.runInInjectionContext()For every Spectator factory, we can easily mock any provider.
Every service that we pass to the mocks property will be mocked using the mockProvider() function.
The mockProvider() function converts each method into a Jasmine spy. (i.e jasmine.createSpy()).
Here are some of the methods it exposes:
dateService.isExpired.and.callThrough();
dateService.isExpired.and.callFake(() => fake);
dateService.isExpired.and.throwError('Error');
dateService.isExpired.andCallFake(() => fake);
However, if you use Jest as test framework and you want to utilize its mocking mechanism instead, import the mockProvider() from @ngneat/spectator/jest.
This will automatically use the jest.fn() function to create a Jest compatible mock instead.
mockProvider() doesn't include properties. In case you need to have properties on your mock you can use 2nd argument:
const createService = createServiceFactory({
service: AuthService,
providers: [
mockProvider(OtherService, {
name: 'Martin',
emitter: new Subject(),
mockedMethod: () => 'mocked'
})
],
});
If a component relies on a service being mocked in the OnInit lifecycle method, change-detection needs to be disabled until after the services have been injected.
To configure this, change the createComponent method to have the detectChanges option set to false and then manually call detectChanges on the spectator after setting up the injected services.
const createComponent = createComponentFactory({
component: WeatherDashboardComponent
});
it('should call the weather api on init', () => {
const spectator = createComponent({
detectChanges: false
});
const weatherService = spectator.inject(WeatherDataApi);
weatherService.getWeatherData.andReturn(of(mockWeatherData));
spectator.detectChanges();
expect(weatherService.getWeatherData).toHaveBeenCalled();
});
If a component relies on a service being mocked in its constructor, you need to create and configure the mock, and to provide the mock when creating the component.
const createComponent = createComponentFactory({
component: WeatherDashboardComponent
});
it('should call the weather api in the constructor', () => {
const weatherService = createSpyObject(WeatherDataApi);
weatherService.getWeatherData.andReturn(of(mockWeatherData));
spectator = createComponent({
providers: [
{ provide: WeatherDataApi, useValue: weatherService }
]
});
expect(weatherService.getWeatherData).toHaveBeenCalled();
});
By default, Spectator uses Jasmine for creating spies. If you are using Jest as test framework instead, you can let Spectator create Jest-compatible spies.
Just import one of the following functions from @ngneat/spectator/jest(instead of @ngneat/spectator), and it will use Jest instead of Jasmine.
createComponentFactory(), createHostFactory(), createServiceFactory(), createHttpFactory(), mockProvider().
import { createServiceFactory, SpectatorService } from '@ngneat/spectator/jest';
import { AuthService } from './auth.service';
import { DateService } from './date.service';
describe('AuthService', () => {
let spectator: SpectatorService<AuthService>;
const createService = createServiceFactory({
service: AuthService,
mocks: [DateService]
});
beforeEach(() => spectator = createService());
it('should not be logged in', () => {
const dateService = spectator.inject<DateService>(DateService);
dateService.isExpired.mockReturnValue(true);
expect(spectator.service.isLoggedIn()).toBeFalsy();
});
it('should be logged in', () => {
const dateService = spectator.inject<DateService>(DateService);
dateService.isExpired.mockReturnValue(false);
expect(spectator.service.isLoggedIn()).toBeTruthy();
});
});
When using the component schematic you can specify the --unitTestRunner flag to jest to have the Jest imports used. In order to Jest imports the default, update angular.json:
"schematics": {
"@ngneat/spectator:spectator-component": {
"unitTestRunner": "jest"
}
}
Please note that the previous --jest flag is deprecated and will be removed in the future.
Like Jest, Spectator also supports Vitest.
To use Vitest, update your vite.config.[m]ts to inline the Spectator package so it gets transformed with Vite before the tests run.
export default defineConfig(({ mode }) => ({
/* ... */
test: {
/* ... */
// inline @ngneat/spectator
server: {
deps: {
inline: ['@ngneat/spectator']
}
}
},
}));
You can then import the functions from @ngneat/spectator/vitest instead of @ngneat/spectator
and it will use Vitest instead of Jasmine.
import { createServiceFactory, SpectatorService } from '@ngneat/spectator/vitest';
import { AuthService } from './auth.service';
import { DateService } from './date.service';
describe('AuthService', () => {
let spectator: SpectatorService<AuthService>;
const createService = createServiceFactory({
service: AuthService,
mocks: [DateService]
});
beforeEach(() => spectator = createService());
it('should not be logged in', () => {
const dateService = spectator.inject<DateService>(DateService);
dateService.isExpired.mockReturnValue(true);
expect(spectator.service.isLoggedIn()).toBeFalsy();
});
it('should be logged in', () => {
const dateService = spectator.inject<DateService>(DateService);
dateService.isExpired.mockReturnValue(false);
expect(spectator.service.isLoggedIn()).toBeTruthy();
});
});
When using the component schematic you can specify the --unitTestRunner flag to vitest to have the Vitest imports used. In order to Vitest imports the default, update angular.json:
"schematics": {
"@ngneat/spectator:spectator-component": {
"unitTestRunner": "vitest"
}
}
Spectator makes testing data services, which use the Angular HTTP module, a lot easier. For example, let's say that you have service with three methods, one performs a GET, one a POST and one performs concurrent requests:
export class TodosDataService {
constructor(private httpClient: HttpClient) {}
getTodos() {
return this.httpClient.get('api/todos');
}
postTodo(id: number) {
return this.httpClient.post('api/todos', { id });
}
collectTodos() {
return merge(
this.httpClient.get('/api1/todos'),
this.httpClient.get('/api2/todos')
);
}
}
The test for the above service should look like:
import { createHttpFactory, HttpMethod } from '@ngneat/spectator';
import { TodosDataService } from './todos-data.service';
describe('HttpClient testing', () => {
let spectator: SpectatorHttp<TodosDataService>;
const createHttp = createHttpFactory(TodosDataService);
beforeEach(() => spectator = createHttp());
it('can test HttpClient.get', () => {
spectator.service.getTodos().subscribe();
spectator.expectOne('api/todos', HttpMethod.GET);
});
it('can test HttpClient.post', () => {
spectator.service.postTodo(1).subscribe();
const req = spectator.expectOne('api/todos', HttpMethod.POST);
expect(req.request.body['id']).toEqual(1);
});
it('can test current http requests', () => {
spectator.service.getTodos().subscribe();
const reqs = spectator.expectConcurrent([
{ url: '/api1/todos', method: HttpMethod.GET },
{ URL: '/api2/todos', method: HttpMethod.GET }
]);
spectator.flushAll(reqs, [{}, {}, {}]);
});
});
We need to create an HTTP factory by using the createHttpFactory() function, passing the service that you want to test. The createHttpFactory() returns a function which can be called to get an instance of SpectatorHttp with the following properties:
controller - A proxy for Angular HttpTestingControllerhttpClient - A proxy for Angular HttpClientservice - The service instanceinject() - A proxy for Angular TestBed.inject()flushEffects() - A proxy for Angular TestBed.flushEffects()runInInjectionContext() - A proxy for Angular TestBed.runInInjectionContext()expectOne() - Expect that a single request was made which matches the given URL and it's method, and return its mock requestIt's possible to define injections which will be available for each test without the need to re-declare them in each test:
// test.ts
import { defineGlobalsInjections } from '@ngneat/spectator';
import { TranslocoModule } from '@ngneat/transloco';
defineGlobalsInjections({
imports: [TranslocoModule],
});
Please be aware, that defineGlobalsInjections() must be called before the modules are loaded. In the default Angular test.ts this means before this line:
context.keys().map(context);
By default, the original component providers (e.g. the providers on the @Component) are not touched.
However, in most cases, you want to access the component's providers in your test or replace them with mocks.
For example:
@Component({
template: '...',
providers: [FooService]
})
class FooComponent {
constructor(private fooService: FooService} {}
// ...
}
Use the componentProviders to replace the FooService provider:
const createComponent = createComponentFactory({
component: FooComponent,
componentProviders: [
{
provide: FooService,
useValue: someThingElse
}
]
})
Or mock the service by using componentMocks:
const createComponent = createComponentFactory({
component: FooComponent,
componentMocks: [FooService]
});
To access the provider, get it from the component injector using the fromComponentInjector parameter:
spectator.inject(FooService, true)
In the same way you can also override the component view providers by using the componentViewProviders and componentViewProvidersMocks.
The same rules also apply to directives using the directiveProviders and directiveMocks parameters.
expect('.zippy__content').not.toExist();
expect('.zippy__content').toHaveLength(3);
expect('.zippy__content').toHaveId('id');
expect(spectator.query('.zippy')).toHaveAttribute('id', 'zippy');
expect(spectator.query('.zippy')).toHaveAttribute({id: 'zippy'});
expect(spectator.query('.checkbox')).toHaveProperty('checked', true);
expect(spectator.query('.img')).toHaveProperty({src: 'assets/myimg.jpg'});
expect(spectator.query('.img')).toContainProperty({src: 'myimg.jpg'});
// Note that toHaveClass accepts classes only in strict order. If order is irrelevant, disable strict mode manually.
expect('.zippy__content').toHaveClass('class');
expect('.zippy__content').toHaveClass('class-a, class-b');
expect('.zippy__content').not.toHaveClass('class-b, class-a');
expect('.zippy__content').toHaveClass(['class-a', 'class-b']);
expect('.zippy__content').not.toHaveClass(['class-b', 'class-a']);
expect('.zippy__content').toHaveClass('class', { strict: false });
expect('.zippy__content').toHaveClass('class-a, class-b', { strict: false });
expect('.zippy__content').toHaveClass('class-b, class-a', { strict: false });
expect('.zippy__content').toHaveClass(['class-b', 'class-a'], { strict: false });
expect('.zippy__content').toHaveClass(['class-b', 'class-a'], { strict: false });
// Note that toHaveText only looks for the existence of a string, not if the string is exactly the same. If you want to verify that the string is completely the same, use toHaveExactText.
// Note that if you want to verify that the string is completely the same, but trimmed first, use toHaveExactTrimmedText.
// Note that if you pass multiple values, Spectator checks the text of each array element against the index of the element found.
expect('.zippy__content').toHaveText('Content');
expect('.zippy__content').toHaveText(['Content A', 'Content B']);
expect('.zippy__content').toHaveText((text) => text.includes('..'));
expect('.zippy__content').toContainText('Content');
expect('.zippy__content').toContainText(['Content A', 'Content B']);
expect('.zippy__content').toHaveExactText('Content');
expect('.zippy__content').toHaveExactText(['Content A', 'Content B']);
expect('.zippy__content').toHaveExactTrimmedText('Content');
expect('.zippy__content').toHaveExactTrimmedText(['Content A', 'Content B']);
expect('.zippy__content').toHaveValue('value');
expect('.zippy__content').toContainValue('value');
// Note this looks for multiple elements with the class and checks the value of each array element against the index of the element found
expect('.zippy__content').toHaveValue(['value a', 'value b']);
expect('.zippy__content').toContainValue(['value a', 'value b']);
expect(spectator.element).toHaveStyle({backgroundColor: 'rgba(0, 0, 0, 0.1)'});
expect('.zippy__content').toHaveData({data: 'role', val: 'admin'});
expect('.checkbox').toBeChecked();
expect('.checkbox').toBeIndeterminate();
expect('.button').toBeDisabled();
expect('div').toBeEmpty();
expect('div').toBeHidden();
expect('element').toBeSelected();
// Notice that due to restrictions within Jest (not applying actual layout logic in virtual DOM), certain matchers may result in false positives. For example width and height set to 0
expect('element').toBeVisible();
expect('input').toBeFocused();
expect('div').toBeMatchedBy('.js-something');
expect(spectator.component.object).toBePartial({ aProperty: 'aValue' });
expect('div').toHaveDescendant('.child');
expect('div').toHaveDescendantWithText({selector: '.child', text: 'text'});
Generate component, service, and directive with Spectator spec templates with Angular Cli: (when using it as default)
Component
ng g cs dashrized-nameng g cs dashrized-name --withHost=trueng g cs dashrized-name --withCustomHost=trueService:
ng g ss dashrized-nameng g ss dashrized-name --isDataService=trueDirective:
ng g ds dashrized-name
To use spectator as the default collection in your Angular CLI project,
add it to your angular.json:
ng config cli.defaultCollection @ngneat/spectator
The spectator schematics extend the default @schematics/angular collection. If you want to set defaults for schematics such as generating components with scss file, you must change the schematics package name from @schematics/angular to @ngneat/spectator in angular.json:
"schematics": {
"@ngneat/spectator:spectator-component": {
"style": "scss"
}
}
The examples in Karma from Angular docs testing developer guide has been reproduced in Spectator and Jest. (For convenience, this is the local version of the Karma examples.)
The Spectator & Jest version can be accessed here.
 Netanel Basal |  Dirk Luijk |  Ben Elliott |
Thanks goes to these wonderful people (emoji key):~~~~
This project follows the all-contributors specification. Contributions of any kind welcome!
FAQs
A powerful tool to simplify your Angular tests
We found that @ngneat/spectator demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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