Question

您好，感谢您抽出宝贵的时间阅读本文！

我非常有兴趣在开发过程中进行单元测试。我是Javascript测试的新手。

我编写了一个函数来读取我们选择的文件，带有输入，但是我不知道如何测试它。

我已经阅读了Jasmine的文档，关于间谍： https://jasmine.github.io/api/2.6/global.html#spyOn

和： https://jasmine.github.io/2.0/introduction.html

代码：

    function readImage() {
    if ( this.files && this.files[0] ) {
        var FR= new FileReader();
        var img = new Image();
        FR.onload = function(e) {
            img.src = e.target.result;
            img.onload = function() {
                ctx.drawImage(img, 0, 0, 512, 512);
            };
        };
        FR.readAsDataURL( this.files[0] );
    }
    return [this.files, FR, img, ctx];
}

fileUpload.onchange = readImage;

我试过的测试：

describe('readImage', function () {
 it('should get at least one file ', function () {

        spyOn(window, 'readImage');

        fileUpload.dispatchEvent(new Event('onchange'));

        expect(window.readImage).toHaveBeenCalled();

    })

});

此外，fileUpload是：

    function createUploadInput() {
    body = document.getElementsByTagName("BODY")[0];
    upload = document.createElement("input");
    upload.setAttribute("type", "file");
    upload.setAttribute("id", "fileUpload");
    body.appendChild(upload);
    return upload;
}

createUploadInput();

我得到的输出：

        Expected spy readImage to have been called.
    Error: Expected spy readImage to have been called.
        at jasmine.Spec.<anonymous> (test/readImageSpec.js:42:34)

我认为这是因为在测试中没有调用readImage方法。原因可能是因为fileUpload.dispatchEvent(new Event('onchange'));什么都不做

你能帮我吗？

我也读过： How to trigger event in JavaScript?

Triggering event for unit testing

Using Jasmine to spy on a function without an object

感谢您的帮助！

我试过了：

it('should get at least one file ', function () {

    spyOn(window, 'readImage');

    fileUpload.dispatchEvent(new Event('change'));

    expect(window.readImage).toHaveBeenCalled();

})

但输出是：

   Expected spy readImage to have been called.
        Error: Expected spy readImage to have been called.
            at jasmine.Spec.<anonymous> (test/readImageSpec.js:42:34)

我也试过了：

it('should get at least one file ', function () {

    spyOn(window, 'readImage');

    fileUpload.onchange();

    expect(window.readImage).toHaveBeenCalled();

})

输出：

Expected spy readImage to have been called.
Error: Expected spy readImage to have been called.
    at jasmine.Spec.<anonymous> (test/readImageSpec.js:42:34)

我还读过：How can I trigger an onchange event manually?

模拟文件上传以测试FileReader

0 个答案: