Question

我正在努力使这项测试工作，但我无法理解如何使用FileReader编写测试。这是我的代码


function Uploader(file) {
    this.file = file;
}

Uploader.prototype =  (function() {

    function upload_file(file, file_contents) {
        var file_data = new FormData()
        file_data.append('filename', file.name)
        file_data.append('mimetype', file.type)
        file_data.append('data', file_contents)
        file_data.append('size', file.size)

        $.ajax({
            url: "/upload/file",
            type: "POST",
            data: file_contents,            
            contentType: file.type,
            success: function(){

                // $("#thumbnail").attr("src", "/upload/thumbnail");    

            },
            error: function(){
                alert("Failed");
            },
            xhr: function() {
                myXhr = $.ajaxSettings.xhr();
                if(myXhr.upload){
                    myXhr.upload.addEventListener('progress',showProgress, false);
                } else {
                    console.log("Upload progress is not supported.");
                }
                return myXhr;
            }
        });
    }

    return {
        upload : function() {
            var self = this,
                reader = new FileReader(),
                file_content = {};

            reader.onload = function(e) {
                file_content = e.target.result.split(',')[1];

                upload_file(self.file, file_content);
            }
        }
    };
})();

这是我的考试


describe("Uploader", function() {
    it("should upload a file successfully", function() {
        spyOn($, "ajax");
        var fakeFile = {};

        var uploader = new Uploader(fakeFile);
        uploader.upload();

        expect($.ajax.mostRecentCall.args[0]["url"]).toEqual("/upload/file");
    })
});

但它永远不会到达reader.onload。

Answer 1

这里的问题是reader.onload的使用很难测试。你可以改用reader.addEventListener，这样就可以窥探全局的FileReader对象并返回一个模拟：

eventListener = jasmine.createSpy();
spyOn(window, "FileReader").andReturn({
 addEventListener: eventListener
})

然后你可以自己发起onload回调：

expect(eventListener.mostRecentCall.args[0]).toEqual('load');
eventListener.mostRecentCall.args[1]({
  target:{
    result:'the result you wanna test'
  }
})

Answer 2

此语法在2.0中已更改。下面的代码给出了一个基于AndreasKöberle答案的例子，但是使用了新的语法

    // create a mock object, its a function with some inspection methods attached
    var eventListener = jasmine.createSpy();

    // this is going to be returned when FileReader is instantiated
    var dummyFileReader = { addEventListener: eventListener };

    // pipe the dummy FileReader to the application when FileReader is called on window
    // this works because window.FileReader() is equivalent to new FileReader()
    spyOn(window, "FileReader").and.returnValue(dummyFileReader)

    // your application will do something like this ..
    var reader = new FileReader();

    // .. and attach the onload event handler
    reader.addEventListener('load', function(e) {

        // obviously this wouldnt be in your app - but it demonstrates that this is the 
        // function called by the last line - onloadHandler(event);
        expect(e.target.result).toEqual('url');

        // jasmine async callback
        done();
    });

    // if addEventListener was called on the spy then mostRecent() will be an object. 
    // if not it will be null so careful with that. the args array contains the 
    // arguments that addEventListener was called with. in our case arg[0] is the event name ..
    expect(eventListener.calls.mostRecent().args[0]).toEqual('load');

    // .. and arg[1] is the event handler function
    var onloadHandler = eventListener.calls.mostRecent().args[1];

    // which means we can make a dummy event object .. 
    var event = { target : { result : 'url' } };

    // .. and call the applications event handler with our test data as if the user had 
    // chosen a file via the picker
    onloadHandler(event);

Answer 3

我认为最好的方法是使用真实的FileReader（不要嘲笑），并传递真实的File或Blob。这样可以提高您的测试覆盖率，并使您的测试不那么脆弱。

如果您的测试未在IE中运行，则可以使用File constructor，例如

const fakeFile = new File(["some contents"], "file.txt", {type: "text/plain"});

如果需要与IE兼容，则可以构造一个Blob并将其看起来像一个文件：

const fakeFile = new Blob(["some contents"]);
fakeFile.name = "file.txt";
fakeFile.type = "text/plain";

FileReader可以读取这些对象中的任何一个，因此无需对其进行模拟。

Answer 4

我发现自己最容易做下一步。

模拟blob文件
在测试环境中运行 reader.onload 。

结果 - 我没有模拟Filereader

＆＃13;

//    CONTROLLER

$scope.handleFile = function (e) {

            var f = e[0];

            $scope.myFile = {
                name: "",
                size: "",
                base64: ""
            };
            var reader = new FileReader();
            reader.onload = function (e) {
                        try {
                            var buffer = e.target.result;
                            $scope.myFile = {
                                name: f.name,
                                size: f.size,
                                base64: XLSX.arrayBufferToBase64(buffer)
                            };
                            $scope.$apply();

                        } catch (error) {
                            $scope.error = "ERROR!";
                            $scope.$apply();
                        }
                    };

reader.readAsArrayBuffer(f);
//run in test env
if ( typeof jasmine == 'object') {reader.onload(e)}
}

//JASMINE TEST

it('handleFile    0', function () {


    var  fileContentsEncodedInHex = ["\x45\x6e\x63\x6f\x64\x65\x49\x6e\x48\x65\x78\x42\x65\x63\x61\x75\x73\x65\x42\x69\x6e\x61\x72\x79\x46\x69\x6c\x65\x73\x43\x6f\x6e\x74\x61\x69\x6e\x55\x6e\x70\x72\x69\x6e\x74\x61\x62\x6c\x65\x43\x68\x61\x72\x61\x63\x74\x65\x72\x73"];
    var blob = new Blob(fileContentsEncodedInHex);
    blob.type = 'application/zip';
    blob.name = 'name';
    blob.size = 11111;
    var e = {0: blob, target: {result: {}}};

    $scope.handleFile(e);
    expect($scope.error ).toEqual("");

});

＆＃13;

Answer 5

我也面临类似的问题，并且无需使用addeventlistener就可以实现它。我曾经使用过onloadend，所以下面是我的工作。我的ts文件包含以下代码：-

    let reader = new FileReader();
    reader.onloadend = function() {
                let dataUrl = reader.result;
                // Some working here
            };
    reader.readAsDataURL(blob);

我的规格文件（测试）案例代码：-

 let mockFileReader = {
            result:'',
            readAsDataURL:(blobInput)=> {
                console.log('readAsDataURL');
            },
            onloadend:()=> {
                console.log('onloadend');
            }
        };

    spyOn<any>(window, 'FileReader').and.returnValue(mockFileReader);
    spyOn<any>(mockFileReader, 'readAsDataURL').and.callFake((blobInput)=> {
        // debug your running application and assign to "encodedString" whatever 
        //value comes actually after using readAsDataURL for e.g. 
        //"data:*/*;base64,XoteIKsldk......"
        mockFileReader.result = encodedString;
        mockFileReader.onloadend();
    });

通过这种方法，您模拟了FileReader对象，并向您自己的“ readAsDataURL”返回了伪造的调用。因此，现在当您的实际代码调用“ reasAsDataURL”时，将调用您的伪函数，其中您在“结果”中分配了编码字符串，并调用了已经在代码（.ts）文件中分配了功能的“ onloadend”函数。因此，它被调用具有预期的结果。希望对您有所帮助。

Answer 6

当从onloadend调用readAsDataURL时，我很难弄清楚如何测试。这是我最后得到的转储。

生产代码：

loadFileDataIntoChargeback(tempFileList) {
        var fileNamesAndData = [];
        for (var i = 0, f; f = tempFileList[i]; i++) {
            let theFile = tempFileList[i];
            var reader = new FileReader();
            reader.onloadend = ((theFile) => {
                return (fileData) => {
                    var insertionIndex = this.chargeback.fileList.length;
                    this.chargeback.fileList.push({ FileName: theFile.name, Data: fileData.target.result, FileType: theFile.type });
                    this.loadFilePreviews(theFile, insertionIndex);
                }
            })(f);
            reader.readAsDataURL(f);
        }
        this.fileInputPath = "";
    }

测试代码：

describe('when the files are loaded into the chargeback', () => {
            it('loads file previews', () => {
                let mockFileReader = {
                    target: { result: '' },
                    readAsDataURL: (blobInput) => {},
                    onloadend: () => {}
                };
                spyOn(chargeback, "loadFilePreviews");
                spyOn(window, 'FileReader').and.returnValue(mockFileReader);
                spyOn(mockFileReader, 'readAsDataURL').and.callFake((blobInput) => {
                    mockFileReader.onloadend({ target: { result: "data:image/jpeg;base64,/9j/4QAYRXh" } });
                });
                var readFileList = chargeback.getArrayFromFileInput([getImageFile1()]);

                chargeback.loadFileDataIntoChargeback(readFileList);

                expect(chargeback.loadFilePreviews).toHaveBeenCalled();
            });
        });

如何在Jasmine中编写FileReader测试？

6 个答案: