如何在 Angular 中创建基本单元测试

Question

I've a component Strip . It is a simple card in HTML with some numbers and calculation. Here's the code:

import { Component, Input, NgZone, OnInit } from '@angular/core';
import './strip.component.scss';
import { SisenseService } from '../../core/services/sisense.service';

@Component({
    selector: 'app-strip',
    templateUrl: './strip.component.html'
})
export class StripComponent extends BaseCardComponent implements OnInit {
        
    constructor(private zone: NgZone, private sisenseService: SisenseService) {
        super();
    }

    ngOnInit(): void { 
    }
}

I'm injecting 2 services, SisenseService and NgZone .

I'm writing a very simple test case. Here's the spec file:

import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { StripComponent } from './strip.component';
import { CUSTOM_ELEMENTS_SCHEMA, NgZone } from '@angular/core';
import { TranslateModule } from '@ngx-translate/core';
import { SisenseService } from '../../core/services/sisense.service';

describe('StripComponent', () => {
    let component: StripComponent;
    let fixture: ComponentFixture<StripComponent>;
    let sisenseService: SisenseService;
    let ngZone: NgZone;

    beforeEach(async(() => {
        TestBed.configureTestingModule({
            declarations: [StripComponent],
            imports: [TranslateModule.forRoot()],
            schemas: [CUSTOM_ELEMENTS_SCHEMA],
            providers: [SisenseService, NgZone]
        }).compileComponents();
    }));

    beforeEach(() => {
        fixture = TestBed.createComponent(StripComponent);
        component = fixture.componentInstance;
        fixture.detectChanges();
        sisenseService = TestBed.get(SisenseService);
        ngZone = TestBed.get(NgZone);
    });

    it('should create', () => {
        expect(component).toBeTruthy();
    });
});

But it is failing telling me that:

Chrome Headless 76.0.3803.0 (Windows 10) StripComponent should create FAILED Failed: Can't resolve all parameters for NgZone: (?). Error: Can't resolve all parameters for NgZone: (?).

Please point out my mistake.

Answer 1

Try to mock the NgZone and use that in the providers

const mockNgZone = jasmine.createSpyObj('mockNgZone', ['run', 'runOutsideAngular']);
mockNgZone.run.and.callFake(function () {return undefined;});

beforeEach(async(() => {
    TestBed.configureTestingModule({
        declarations: [StripComponent],
        imports: [TranslateModule.forRoot()],
        schemas: [CUSTOM_ELEMENTS_SCHEMA],
        providers: [
            SisenseService,
            {provide: NgZone, useValue: mockNgZone}
        ]
    }).compileComponents();
}));