Mat Table - renderRows 单元测试错误

Question

我在组件中使用 mat 表，并在更新表后调用 renderRows，效果很好。 但是，在我的单元测试中，我遇到了以下错误。

在 afterAll 中抛出了一个错误 失败：无法读取未定义的属性“renderRows” 错误属性：对象（{ longStack：'TypeError：无法读取未定义的属性'renderRows' 在 SafeSubscriber._next (http://localhost:9876/karma_webpack/src/app/product-management/tax-configuration/tax-configuration.component.ts:80:23)

spec.ts 文件 ->

import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { TaxConfigurationComponent } from './tax-configuration.component';
import { MatTableModule } from '@angular/material/table';
import { MatFormFieldModule } from '@angular/material/form-field';
import { MatInputModule } from '@angular/material/input';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { HttpClientTestingModule } from '@angular/common/http/testing';
import { NotificationService } from 'src/app/services/custom/notification.service';
import { TaxConfigurationService } from 'src/app/services/products/tax-configuration.service';
import { MockTaxConfigurationService } from 'src/app/services/products/tax-configuration.service.mock.spec';
import { throwError } from 'rxjs';
import { MatButtonModule } from '@angular/material/button';

describe('TaxConfigurationComponent', () => {
    let component: TaxConfigurationComponent;
    let fixture: ComponentFixture<TaxConfigurationComponent>;
    let _notificationService: NotificationService;
    let _taxService: TaxConfigurationService;

    beforeEach(async(() => {
        TestBed.configureTestingModule({
            declarations: [TaxConfigurationComponent],
            imports: [
                BrowserAnimationsModule,
                MatTableModule,
                MatFormFieldModule,
                MatInputModule,
                FormsModule,
                ReactiveFormsModule,
                HttpClientTestingModule,
                MatButtonModule,
            ],
            providers: [{ provide: TaxConfigurationService, useClass: MockTaxConfigurationService }],
        }).compileComponents();
    }));

    beforeEach(() => {
        fixture = TestBed.createComponent(TaxConfigurationComponent);
        component = fixture.componentInstance;
        fixture.detectChanges();
        _taxService = TestBed.inject(TaxConfigurationService);
        _notificationService = TestBed.inject(NotificationService);
    });

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

    it('should populate tax table on init', () => {
        expect(component.dataSource.length).toBeGreaterThan(0);
    });

    it('should show an error notification when "getTaxConfig()" errors out', () => {
        spyOn(_notificationService, 'startNotification').and.callThrough();
        spyOn(_taxService, 'getTaxConfig').and.returnValue(throwError('Error'));
        component.ngOnInit();
        expect(_notificationService.startNotification).toHaveBeenCalledWith(
            'An error occurred while fetching data.',
            'nc-notification--error',
            'priority_high'
        );
    });
});

component.ts 文件 ->

ngOnInit(): void {
        this.state = true;
        this.taxForm = new FormGroup({});
        this.populateTaxConfigTable();
    }

    populateTaxConfigTable(): void {
        this._taxService.getTaxConfig().subscribe((results) => {
            results.forEach((result) => {
                const rowEntry = {
                    name: result.resourceName,
                    category: result.resourceCategory,
                    id: result.resourceId,
                    tsc: new FormControl(result.taxTsc, [
                        Validators.required,
                        Validators.pattern(regexPattern),
                        Validators.max(100),
                        Validators.min(0),
                    ]),
                    ot: new FormControl(result.taxOt, [
                        Validators.required,
                        Validators.pattern(regexPattern),
                        Validators.max(100),
                        Validators.min(0),
                    ]),
                    vat: new FormControl(result.taxVat, [
                        Validators.required,
                        Validators.pattern(regexPattern),
                        Validators.max(100),
                        Validators.min(0),
                    ]),
                };
                const tscControlName = rowEntry.id + 'tsc';
                const otControlName = rowEntry.id + 'ot';
                const vatControlName = rowEntry.id + 'vat';
                this.taxForm.addControl(tscControlName, rowEntry.tsc);
                this.taxForm.addControl(otControlName, rowEntry.ot);
                this.taxForm.addControl(vatControlName, rowEntry.vat);
                this.dataSource.push(rowEntry);
            });
            this.table.renderRows();
            this.state = false;
        }, (error) => {
            this._notificationService.startNotification('An error occurred while fetching data.',
            'nc-notification--error', 'priority_high');
        });
    }

当我评论this.table.renderRows 时，单元测试正在运行，没有任何问题。对这里的问题有任何想法吗？

编辑：

模拟税配置服务

export class MockTaxConfigurationService {
    getTaxConfig(): Observable<ResourceTaxes[]> {
        return of([mockResourceTaxes, mockResourceTaxes]);
    }

    updateTaxConfig(data: TaxPostData[]): Observable<TaxResponseData[]> {
        return of([mockTaxResponseData]);
    }
}

使用 viewChild ->

export class TaxConfigurationComponent implements OnInit {
    @ViewChild(MatTable) table: MatTable<any>;
    displayedColumns: string[] = ['name', 'tsc', 'ot', 'vat'];
    taxForm: FormGroup;
    dataSource: TaxTableData[] = [];
    state = false; // Loading state
    shouldDisableSave = false;

    constructor(
        private _notificationService: NotificationService,
        private _taxService: TaxConfigurationService) {}

    ngOnInit(): void {
        this.state = true;
        this.taxForm = new FormGroup({});
        this.populateTaxConfigTable();
    }

   ...
}

Answer 1

我认为您的单元测试实际上揭示了一个您没有遇到的问题，因为您的实际税务配置服务花费了足够长的时间，直到表格被实际初始化。

onInit 中没有子视图。它在生命周期的后期设置。为此，您需要使用 ngAfterViewInit。

看看here

错误显示在您的测试中，因为您的beforeEach 中的第一个fixture.detectChanges() 触发了ngOnInit。您的税务服务模拟会立即发出您的模拟值，因为 ViewChild 直到 ngAfterViewInit 才初始化，您的表仍然是 undefined