I am trying to test a component that receives a reference to ElementRef through DI.
import { Component, OnInit, ElementRef } from '@angular/core';
@Component({
selector: 'cp',
templateUrl: '...',
styleUrls: ['...']
})
export class MyComponent implements OnInit {
constructor(private elementRef: ElementRef) {
//stuffs
}
ngAfterViewInit() {
// things
}
ngOnInit() {
}
}
and the test:
import {
beforeEach,
beforeEachProviders,
describe,
expect,
it,
inject,
} from '@angular/core/testing';
import { ComponentFixture, TestComponentBuilder } from '@angular/compiler/testing';
import { Component, Renderer, ElementRef } from '@angular/core';
import { By } from '@angular/platform-browser';
describe('Component: My', () => {
let builder: TestComponentBuilder;
beforeEachProviders(() => [MyComponent]);
beforeEach(inject([TestComponentBuilder], function (tcb: TestComponentBuilder) {
builder = tcb;
}));
it('should inject the component', inject([MyComponent],
(component: MyComponent) => {
expect(component).toBeTruthy();
}));
it('should create the component', inject([], () => {
return builder.createAsync(MyComponentTestController)
.then((fixture: ComponentFixture<any>) => {
let query = fixture.debugElement.query(By.directive(MyComponent));
expect(query).toBeTruthy();
expect(query.componentInstance).toBeTruthy();
});
}));
});
@Component({
selector: 'test',
template: `
<cp></cp>
`,
directives: [MyComponent]
})
class MyTestController {
}
Both the component and the test blueprint have been generated by Angular-cli. Now, I can't figure out which provider, if any, I should add in the beforeEachProviders
for the injection of ElementRef to be successful. When I run ng test
I got Error: No provider for ElementRef! (MyComponent -> ElementRef)
.
I encounter Can't resolve all parameters for ElementRef: (?)
Error using the mock from @gilad-s in angular 2.4
Modified the mock class to:
export class MockElementRef extends ElementRef {
constructor() { super(null); }
}
resolves the test error.
Reading from the angular source code here: https://github.com/angular/angular/blob/master/packages/core/testing/src/component_fixture.ts#L17-L60
the elementRef of the fixture is not created from the mock injection. And in normal development, we do not explicitly provide ElementRef
when injecting to a component. I think TestBed
should allow the same behaviour.