如何使用单元测试来测试getElementsByClassName方法？

Question

我想测试一个函数，当有7个以上页面时，将一个类名添加到div容器中。但是不要让它起作用。

尝试了spyOn，但没有结果。

构造函数

constructor($document, $element) {
  this.$document = $document;
  this.$element = $element;
}

onInit函数

$onInit() {
const listPages = this.element.children;
const totalPages = listPages.length;

if (totalPages> 7) {
  this.$document[0].getElementsByClassName('test-container')[0].className += ' test';
}
}

我尝试过：

beforeEach(() => {
this.documentSpy = jasmine.createSpyObj('$document', ['getElementsByClassName']);
this.elementSpy = jasmine.createSpyObj('$element', ['find']);
});


fit('should add class test when styles contain atleast 7 steps', () => {
    let stepPage = new stepPageController(this.documentSpy, this.elementSpy);
    stepPage.element = {
        children: [
            { step: ['current'] },
            { step: ['step2'] },
            { step: ['step3'] },
            { step: ['step4'] },
            { step: ['step5'] },
            { step: ['step6'] },
            { step: ['step7'] },
            { step: ['step8'] }
        ]
    };

    const element = angular.element(this.$document[0].body).append('<div class="test-container"></div>');
    spyOn(stepPage.$document[0], 'getElementsByClassName').and.returnValue(element);

    // When
    stepPage.$onInit();

    // Then
    expect(stepPage.$document[0].getElementsByClassName('test-container')[0].className).toBe('test');
});

但是将其作为错误：TypeError：无法读取未定义的属性“ 0”