javascript 从函数内的量角器承诺中返回一个值

Returning a value from a from a protractor promise inside a function

提问by luker02

I'm trying to get text from a page and then use that text further down in the spec to assert on another element.

我试图从页面中获取文本，然后在规范中进一步使用该文本来断言另一个元素。

I've pasted a very simple spec you can run that shows you can't return a value from a function if the function's return statement is inside a protractor promise return txt;(line 24)…

我已经粘贴了一个可以运行的非常简单的规范，它表明如果函数的 return 语句在量角器承诺内return txt;（第 24 行），则不能从函数返回值……

describe('My Test', function () {
    var tempVariable;

    it('should go get some text from the page', function () {
        browser.get('https://angularjs.org/');
        tempVariable = getTextFromElement();    //it appears javascript immediately sets this variable before waiting for protractor to return the value
    });

    it('should do some random other stuff', function () {
        element.all(by.cssContainingText('a', 'Learn')).get(0).click();
        element.all(by.cssContainingText('a', 'Case Studies')).get(0).click();
        element.all(by.cssContainingText('a', ' Home')).get(0).click();
    });

    it('should be able to use the text from the first page in this test', function () {
        console.log('\ntempVariable: ' + tempVariable);    //this is undefined!
        expect(typeof tempVariable).not.toBe('undefined', 'failed: tempVariable was undefined!');
    });
});

function getTextFromElement() {
    $('a.learn-link').getText().then(function (txt) {
        console.log('\nInitial text:   ' + txt);
        return txt;     //how do we return this so it's available to other 'it' blocks?
    });
}

Updated snippet of code following @alecxe answer and my comment.

在@alecxe 回答和我的评论之后更新了代码片段。

I am attempting to contruct an object from various text on a page and return it to assert on in a later page...

我正在尝试从页面上的各种文本构建一个对象，并将其返回以在稍后的页面中进行断言...

function getRandomProductFromList() {
    var Product = function (line, name, subname, units) {
        this.line       = line;
        this.name       = name;
        this.subname    = subname;
        this.units      = units;
    };

    var myProduct = new Product();

    myProduct.line = 'Ford';
    myProduct.units = 235;

    //select a random product on the page and add it to 'myProduct'
    var allProducts = element.all('div.product');
    allProducts.count().then(function (count) {
        var randomIndex = Math.floor(Math.random() * count);
        var productName = allProducts.get(randomIndex);

        productName.getText().then(function (prodName) {
            myProduct.name = prodName;
            productName.click();
        });
    });

    //If a sub-product can be chosen, select it and add it to 'myProduct'
    var subproduct = $('div.subproduct');
    subproduct.isDisplayed().then(function (subProductExists) {
        if (subProductExists) {
            subproduct.getText().then(function (subProductName) {
                myProduct.subname = subProductName;
            });
            subproduct.click();
        }
    }, function (err) {});

    return myProduct;
}

采纳答案by luker02

Thanks to @alecxe for starting me off on the right foot.

感谢@alecxe 让我从右脚开始。

I found a solution I am now using quite a bit after reading this.

阅读本文后，我找到了一个解决方案，我现在正在使用它。

By passing an object by reference, you can add properties on the fly and use them later in your spec.

通过引用传递对象，您可以动态添加属性并稍后在规范中使用它们。

Example:

例子：

describe('My Test', function () {
    var tempObject = {};

    it('should go get some text from the page', function () {
        browser.get('https://angularjs.org/');
        getTextFromElement(tempObject);    //pass an object by reference to populate with page text
    });

    it('should do some random other stuff', function () {
        $('div.someDiv').click();
    });

    it('should be able to use the text from the first page in this test', function () {
        console.log(tempObject.textFromFirstPage); //works!
    });
});

function getTextFromElement(tempObject) {
    $('a.some-link').getText().then(function (txt) {
        tempObject.textFromFirstPage = txt;
    });
}

回答by alecxe

First of all, you are not returning anything from the function:

首先，您没有从函数返回任何内容：

function getTextFromElement() {
    return $('a.learn-link').getText();
}

Now, this function would return you a promisewhich you need to resolve before using:

现在，这个函数会返回一个你需要在使用前解决的承诺：

it('should be able to use the text from the first page in this test', function () {
    tempVariable.then(function (tempVariableValue) {
        console.log('\ntempVariable: ' + tempVariableValue);    
        expect(typeof tempVariableValue).not.toBe('undefined', 'failed: tempVariable was undefined!');
    });
});

Plus, to determine whether a variable is defined or not, I would use toBeDefined()from jasmine-matchers:

另外，要确定变量是否已定义，我将使用toBeDefined()from jasmine-matchers：

expect(tempVariableValue).toBeDefined();

回答by Carlos

None of the above worked for me. This is working for me:

以上都不适合我。这对我有用：

    var item = element.all(by.xpath("some xpath here"));


    this.methodToGetTheText = function () {
       return Promise.resolve(item.getText().then(function (text) {
           return text;
       }));
    }

回答by luker02

Are you calling methodToGetTheText().then(from your spec? The value inside the .then()function should contain your actual page text

你是methodToGetTheText().then(从你的规格打电话吗？.then()函数内的值应包含您的实际页面文本