Angular 7（或2+）中文件上传方法的单元测试如何写

Question

我正在尝试为 angular 中的文件上传方法编写单元测试 7. 在测试中出现以下错误 window。我是 angular 单元测试的新手。有人可以帮忙，如何添加模拟文件以获得完整的代码覆盖率？

TypeError: Cannot set property 'value' of undefined

这是我的单元测试代码（规范文件），

describe('ImportComponent', () => {
    let component: ImportComponent;
    let fixture: ComponentFixture<ImportComponent>;
    let element;

    beforeEach(
        async(() => {
            TestBed.configureTestingModule({
                imports: [ HttpClientModule, RouterTestingModule ],
                declarations: [ ImportComponent ]
            }).compileComponents();
        })
    );

    beforeEach(() => {
        fixture = TestBed.createComponent(ImportComponent);
        component = fixture.componentInstance;
        element = fixture.nativeElement;
        fixture.detectChanges();
    });

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

    it('should upload the file', () => {
        component.importFile();
        const inputEl = element.querySelector('#postal_file');
        const fileList = { 0: { name: 'foo', size: 500001 } };
        inputEl.value = {
            target: {
                files: fileList
            }
        };
        inputEl.dispatchEvent(new Event('change'));     
    });
});

组件中的方法

importFile() {
        const inputEl: HTMLInputElement = this.el.nativeElement.querySelector('#postal_file');
        const fileCount: number = inputEl.files.length;
        const formData = new FormData();
        if (fileCount > 0) {
            formData.append(this.postalFileName, inputEl.files.item(0));
            this.postalService.importPostalCodes(formData).subscribe((data) => {
                this.result = data;
            });
        }
    }

和HTML,

<div class="file-import">
        <form action="" method="post" encType="multipart/form-data">
            <label for="postal_file">Choose File</label>
            <input type="file" name="postal_file" id="postal_file">
            <button type="button" (click)="importFile()">Import</button>
        </form>
    </div>

单元测试没有覆盖所有代码如下图，请帮忙，如何获得100%的代码覆盖率。

Code coverage image

Answer 1

为了上述部分的 100% 代码覆盖率，我添加了以下 2 个测试用例。这对我有用。

it('should upload the file - checkFileExist = true', () => {
    spyOn(component, 'checkFileExist').and.returnValue(true);
    spyOn(postalService,'importPostalCodes').and.callThrough();
    component.importFile();
    expect(postalService.importPostalCodes).toHaveBeenCalled();
});

it('should upload the file - checkFileExist = false', () => {
    spyOn(component, 'checkFileExist').and.returnValue(false);
    spyOn(postalService,'importPostalCodes').and.callThrough();
    component.importFile();
    expect(postalService.importPostalCodes).toHaveBeenCalledTimes(0);
});

Answer 2

测试文件上传和检查模型值集的简单方法。

.html

<input (change)="onFileSelected()" #fileInput type="file" id="file">

.ts

uploadedFile : any

onFileSelected() {
  const inputNode: any = document.querySelector('#file');
  this.uploadedFile  = inputNode.files[0];
}

spec.ts

it('should detect file input change and set uploadedFile  model', () => {
    const dataTransfer = new DataTransfer()
    dataTransfer.items.add(new File([''], 'test-file.pdf'))

    const inputDebugEl  = fixture.debugElement.query(By.css('input[type=file]'));
    inputDebugEl.nativeElement.files = dataTransfer.files;

    inputDebugEl.nativeElement.dispatchEvent(new InputEvent('change'));

    fixture.detectChanges();

    expect(component.uploadedFile).toBeTruthy()
    expect(component.uploadedFile).toBe('test-file.pdf')
    
});

it('file change event should arrive in handler', () => {
    const element = fixture.nativeElement;
    const input = element.querySelector('#file');
    spyOn(component, 'onFileSelected');
    input.dispatchEvent(new Event('change'));
    fixture.detectChanges();
    expect(component.onFileSelected).toHaveBeenCalled();
});

Angular 7（或2+）中文件上传方法的单元测试如何写

How to write the unit testing for the file upload method in the Angular 7 (or 2+)

angular

karma-jasmine

angular-test