Helper function for creating angular mocks for test.
Sure, you could flip a flag on schema errors to make your component dependencies not matter. Or you could use this to mock them out and have the ability to assert on their inputs or emit on an output to assert on a side effect.
- Mocked component with the same selector
- Inputs and Outputs with alias support
- Each component instance has its own EventEmitter instances for outputs
- Mocked component templates are
ng-contenttags to allow transclusion - When
@ContentChildis present, then all of them will be wrapped as[data-key="_id_"]andng-contentwith[data-key="ng-content"] - Allows ng-model binding (You will have to add FormsModule to TestBed imports)
- Mocks Reactive Forms (You will have to add ReactiveFormsModule to TestBed imports)
- __simulateChange - calls
onChangedon the mocked component bound to a FormControl - __simulateTouch - calls
onTouchedon the mocked component bound to a FormControl
- __simulateChange - calls
- exportAs support
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { By } from '@angular/platform-browser';
import { MockComponent, MockedComponent, MockRender } from 'ng-mocks';
import { DependencyComponent } from './dependency.component';
import { TestedComponent } from './tested.component';
describe('MockComponent', () => {
let fixture: ComponentFixture<TestedComponent>;
let component: TestedComponent;
beforeEach(() => {
TestBed.configureTestingModule({
declarations: [TestedComponent, MockComponent(DependencyComponent)],
});
fixture = TestBed.createComponent(TestedComponent);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('should send the correct value to the dependency component input', () => {
const mockedComponent = fixture.debugElement.query(By.css('dependency-component-selector'))
.componentInstance as DependencyComponent; // casting to retain type safety
// let's pretend Dependency Component (unmocked) has 'someInput' as an input
// the input value will be passed into the mocked component so you can assert on it
component.value = 'foo';
fixture.detectChanges();
// if you casted mockedComponent as the original component type then this is type safe
expect(mockedComponent.someInput).toEqual('foo');
});
it('should do something when the dependency component emits on its output', () => {
spyOn(component, 'trigger');
const mockedComponent = fixture.debugElement.query(By.directive(DependencyComponent))
.componentInstance as DependencyComponent; // casting to retain type safety
// again, let's pretend DependencyComponent has an output called 'someOutput'
// emit on the output that MockComponent setup when generating the mock of Dependency Component
// if you casted mockedComponent as the original component type then this is type safe
mockedComponent.someOutput.emit({
payload: 'foo',
});
// assert on some side effect
expect(component.trigger).toHaveBeenCalledWith({
payload: 'foo',
});
});
it('should render something inside of the dependency component', () => {
const localFixture = MockRender(`
<dependency-component-selector>
<p>inside content</p>
</dependency-component-selector>
`);
// because component does not have any @ContentChild we can access html directly.
// assert on some side effect
const mockedNgContent = localFixture.debugElement.query(By.directive(DependencyComponent)).nativeElement.innerHTML;
expect(mockedNgContent).toContain('<p>inside content</p>');
});
it('should render something inside of the dependency component', () => {
const localFixture = MockRender(`
<dependency-component-selector>
<ng-template #something><p>inside template</p></ng-template>
<p>inside content</p>
</dependency-component-selector>
`);
// injected ng-content says as it was.
const mockedNgContent = localFixture.debugElement.query(By.directive(DependencyComponent)).nativeElement.innerHTML;
expect(mockedNgContent).toContain('<p>inside content</p>');
// because component does have @ContentChild we need to render them first with proper context.
const mockedElement = localFixture.debugElement.query(By.directive(DependencyComponent));
const mockedComponent: MockedComponent<DependencyComponent> = mockedElement.componentInstance;
mockedComponent.__render('something');
localFixture.detectChanges();
const mockedNgTemplate = mockedElement.query(By.css('[data-key="something"]')).nativeElement.innerHTML;
expect(mockedNgTemplate).toContain('<p>inside template</p>');
});
});- Mocked directive with the same selector
- Inputs and Outputs with alias support
- Each directive instance has its own EventEmitter instances for outputs
- exportAs support
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { By } from '@angular/platform-browser';
import { MockDirective, MockHelper } from 'ng-mocks';
import { DependencyDirective } from './dependency.directive';
import { TestedComponent } from './tested.component';
describe('MockDirective', () => {
let fixture: ComponentFixture<TestedComponent>;
let component: TestedComponent;
beforeEach(() => {
TestBed.configureTestingModule({
declarations: [TestedComponent, MockDirective(DependencyDirective)],
});
fixture = TestBed.createComponent(TestedComponent);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('should send the correct value to the dependency component input', () => {
component.value = 'foo';
fixture.detectChanges();
// let's pretend Dependency Directive (unmocked) has 'someInput' as an input
// the input value will be passed into the mocked directive so you can assert on it
const mockedDirectiveInstance = MockHelper.getDirective(
fixture.debugElement.query(By.css('span')),
DependencyDirective
);
expect(mockedDirectiveInstance).toBeTruthy();
if (mockedDirectiveInstance) {
expect(mockedDirectiveInstance.someInput).toEqual('foo');
}
// assert on some side effect
});
it('should do something when the dependency directive emits on its output', () => {
spyOn(component, 'trigger');
fixture.detectChanges();
// again, let's pretend DependencyDirective has an output called 'someOutput'
// emit on the output that MockDirective setup when generating the mock of Dependency Directive
const mockedDirectiveInstance = MockHelper.getDirective(
fixture.debugElement.query(By.css('span')),
DependencyDirective
);
expect(mockedDirectiveInstance).toBeTruthy();
if (mockedDirectiveInstance) {
mockedDirectiveInstance.someOutput.emit({
payload: 'foo',
}); // if you casted mockedDirective as the original component type then this is type safe
}
// assert on some side effect
});
});It's important to render a structural directive first with right context, when assertions should be done on its nested elements.
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { MockDirective, MockedDirective, MockHelper } from 'ng-mocks';
import { DependencyDirective } from './dependency.directive';
import { TestedComponent } from './tested.component';
describe('MockDirective', () => {
let fixture: ComponentFixture<TestedComponent>;
let component: TestedComponent;
beforeEach(() => {
TestBed.configureTestingModule({
declarations: [TestedComponent, MockDirective(DependencyDirective)],
});
fixture = TestBed.createComponent(TestedComponent);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('should send the correct value to the dependency component input', () => {
component.value = 'foo';
fixture.detectChanges();
// IMPORTANT: by default structural directives aren't rendered.
// Because we can't automatically detect when and with which context they should be rendered.
// Usually developer knows context and can render it manually with proper setup.
const mockedDirectiveInstance = MockHelper.findDirective(
fixture.debugElement,
DependencyDirective
) as MockedDirective<DependencyDirective>;
// now we assert that nothing has been rendered inside of the structural directive by default.
expect(fixture.debugElement.nativeElement.innerText).not.toContain('content');
// and now we render it manually.
mockedDirectiveInstance.__render();
expect(fixture.debugElement.nativeElement.innerText).toContain('content');
// let's pretend Dependency Directive (unmocked) has 'someInput' as an input
// the input value will be passed into the mocked directive so you can assert on it
expect(mockedDirectiveInstance).toBeTruthy();
if (mockedDirectiveInstance) {
expect(mockedDirectiveInstance.someInput).toEqual('foo');
}
// assert on some side effect
});
});- Mocked pipe with the same name.
- Ability to override the transform function with a type-safe function
- Default transform is () => undefined to prevent problems with chaining
Personally, I found the best thing to do for assertions is to override the transform to write the args so that I can assert on the arguments.
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { By } from '@angular/platform-browser';
import { MockPipe } from 'ng-mocks';
import { DependencyPipe } from './dependency.pipe';
import { TestedComponent } from './tested.component';
describe('MockPipe', () => {
let fixture: ComponentFixture<TestedComponent>;
beforeEach(() => {
TestBed.configureTestingModule({
declarations: [
TestedComponent,
// alternatively you can use MockPipes to mock multiple but you lose the ability to override
MockPipe(DependencyPipe, (...args) => JSON.stringify(args)),
],
});
fixture = TestBed.createComponent(TestedComponent);
fixture.detectChanges();
});
describe('with transform override', () => {
it('should return the result of the provided transform function', () => {
expect(fixture.debugElement.query(By.css('span')).nativeElement.innerHTML).toEqual('["foo"]');
});
});
});- Set value on the formControl by calling __simulateChange
- Set touched on the formControl by calling __simulateTouch
- Use the
MockedComponenttype to stay typesafe:MockedComponent<YourReactiveFormComponent>
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { ReactiveFormsModule } from '@angular/forms';
import { By } from '@angular/platform-browser';
import { MockComponent, MockedComponent } from 'ng-mocks';
import { DependencyComponent } from './dependency.component';
import { TestedComponent } from './tested.component';
describe('MockReactiveForms', () => {
let fixture: ComponentFixture<TestedComponent>;
let component: TestedComponent;
beforeEach(() => {
TestBed.configureTestingModule({
declarations: [TestedComponent, MockComponent(DependencyComponent)],
imports: [ReactiveFormsModule],
});
fixture = TestBed.createComponent(TestedComponent);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('should send the correct value to the dependency component input', () => {
const mockedReactiveFormComponent = fixture.debugElement.query(By.css('dependency-component-selector'))
.componentInstance as MockedComponent<DependencyComponent>; // casting to retain type safety
mockedReactiveFormComponent.__simulateChange('foo');
expect(component.formControl.value).toBe('foo');
});
});It figures out if it is a component, directive, or pipe and mocks it for you
- Mocks all components, directives, and pipes using MockDeclaration
- Providers are all mocked as empty objects
- Module Dependencies are also mocked
For providers I typically will use TestBed.get(SomeProvider) and extend it using a library like ts-mocks.
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { MockModule } from 'ng-mocks';
import { DependencyModule } from './dependency.module';
import { TestedComponent } from './tested.component';
describe('MockModule', () => {
let fixture: ComponentFixture<TestedComponent>;
let component: TestedComponent;
beforeEach(() => {
TestBed.configureTestingModule({
declarations: [TestedComponent],
imports: [MockModule(DependencyModule)],
});
fixture = TestBed.createComponent(TestedComponent);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('renders nothing without any error', () => {
expect(component).toBeTruthy();
});
});Providers simple way to render anything, change @Inputs and @Outputs of testing component, directives etc.
import { TestBed } from '@angular/core/testing';
import { By } from '@angular/platform-browser';
import { MockModule, MockRender } from 'ng-mocks';
import { DependencyModule } from './dependency.module';
import { TestedComponent } from './tested.component';
describe('MockRender', () => {
beforeEach(() => {
TestBed.configureTestingModule({
declarations: [TestedComponent],
imports: [MockModule(DependencyModule)],
});
});
it('renders template', () => {
const spy = jasmine.createSpy();
const fixture = MockRender(
`
<tested (trigger)="myListener1($event)" [value1]="myParam1" value2="check">
<ng-template #header>
something as ng-template
</ng-template>
something as ng-content
</tested>
`,
{
myListener1: spy,
myParam1: 'something1',
}
);
// assert on some side effect
const componentInstance = fixture.debugElement.query(By.directive(TestedComponent))
.componentInstance as TestedComponent;
componentInstance.trigger.emit('foo1');
expect(componentInstance.value1).toEqual('something1');
expect(componentInstance.value2).toEqual('check');
expect(spy).toHaveBeenCalledWith('foo1');
});
it('renders component', () => {
const spy = jasmine.createSpy();
// generates template like:
// <tested [value1]="value1" [value2]="value2" (trigger)="trigger"></tested>
// and returns fixture with a component with properties value1, value2 and empty callback trigger.
const fixture = MockRender(TestedComponent, {
trigger: spy,
value1: 'something2',
});
// assert on some side effect
const componentInstance = fixture.debugElement.query(By.directive(TestedComponent))
.componentInstance as TestedComponent;
componentInstance.trigger.emit('foo2');
expect(componentInstance.value1).toEqual('something2');
expect(componentInstance.value2).toBeUndefined();
expect(spy).toHaveBeenCalledWith('foo2');
});
});MockHelper provides 3 methods to get attribute and structural directives from an element.
MockHelper.getDirective(fixture.debugElement, Directive) -
returns attribute or structural directive which belongs to current element.
MockHelper.findDirective(fixture.debugElement, Directive) -
returns first found attribute or structural directive which belongs to current element or any child.
MockHelper.findDirectives(fixture.debugElement, Directive)
returns all found attribute or structural directives which belong to current element and all its child.
More detailed examples can be found in e2e and in examples directories in the repo.
Report it as an issue or submit a PR. I'm open to contributions.