使用 Selenium WebDriver 读取 JavaScript 变量 [英] Reading JavaScript variables using Selenium WebDriver

问题描述

我正在使用 Selenium WebDriver (Java) 和 TestNG 在我创建的网站上进行一些测试.在这个网站中，我也有 JavaScript，在一些函数中，它返回值，并通过 console.log() 将值输出到浏览器控制台.

我想知道是否有一种简单的方法可以让 Selenium WebDriver 访问一些 JavaScript 信息，以便我可以使用 TestNG 执行断言.

我对 Selenium 很陌生，但我知道您可以执行以下操作:

WebDriver driver = new ChromeDriver();driver.findElement(By.id("btn")).click();

那么我可以使用 WebDriver 来读取网站上的 JavaScript 吗?

<小时>

澄清

看起来人们假设我正在尝试通过 Selenium执行"JavaScript 代码.

事实并非如此.相反，我正在尝试使用 Selenium 存储已定义的 JavaScript 变量.

基本上，我希望 Selenium 能够获取 JavaScript 变量的值，将其存储在本地，然后对其进行断言测试.

<小时>

尝试 1

假设我的网站有以下 JS 代码:

$(document).ready(function() {var foo = $(#"input-field-val").val();函数 returnFoo() {返回 foo;}});

根据我的阅读和理解，在我单独的 Selenium 测试文件 (Selenium.java) 中，我应该能够做这样的事情?:

公共类硒{WebDriver 驱动程序 = 新的 FirefoxDriver();JavascriptExecutor js = (JavascriptExecutor) 驱动程序；@测试公共无效 testSample() {driver.get("www.mywebsite.com");js.executeScript("alert(returnFoo());");}}

我做了与上面类似的事情，但没有弹出警告框.相反，我收到一条错误消息:

线程main"org.openqa.selenium.WebDriverException 中的异常:ReferenceError: returnFoo 未定义

我很确定我不明白它所说的 JS 变量是什么意思

<块引用>

不应是闭包或局部变量的一部分

我也尝试在 $(document).ready(function()... 上方定义一个全局变量，并且设置在 function returnFoo() 内，但仍然不起作用.

<小时>

尝试 2

我已经将 foo 和 returnFoo() 移到了 $(document).ready(function()... 之外. 修复了我在上面 Attempt 1 中得到的 ReferenceError 消息.

我还给了 foo 一个值，所以我的 JS 代码看起来像这样:

var foo = "Selenium 测试运行";$(document).ready(function() {...});函数 returnFoo() {返回 foo;}

现在，我很难将 returnFoo() 的返回值分配给 Selenium 测试中的局部变量.这是我尝试过的:

public static void main(String[] args) {WebDriver 驱动程序 = 新的 FirefoxDriver();JavascriptExecutor js = (JavascriptExecutor) 驱动程序；driver.get("http://localhost:8080/HTML5TestApp/prod.html");Object val = js.executeScript("window.returnFoo();");System.out.println(val);}

但是控制台显示null而不是Selenium test run"的实际值.

尝试 2 - 解决方案

看起来如果我执行 Object val = js.executeScript("alert(returnFoo());"); 我得到了 foo 的值.<小时>

解决方案

感谢下面 Martin Foot 的解决方案，这是我针对我的问题提出的解决方案.

在我的 JavaScript 文件中，我创建了一个 var 和一个 setter/getter 函数，如下所示:

index.js

var seleniumGlobal;$(document).ready(function() {...)};函数 setSG(toSet) {seleniumGlobal = toSet;}函数 getSG() {返回 seleniumGlobal；}

SampleTest.java

//做所有必要的导入公共类 SampleTest {WebDriver 驱动程序 = 新的 FirefoxDriver();JavascriptExecutor js = (JavascriptExecutor) 驱动程序；@测试公共无效 testPrintVal() {String sgVal = (String) js.executeScript("alert(getSG());");Assert.assertEquals("seleniumGlobal 的新值", sgVal);}}

因此，每当我的 JavaScript 中的某些代码通过 setter 方法设置我的 seleniumGlobal 变量时，我都可以通过我的 Selenium 测试调用它并对其进行断言.

这可能不是最有效的方法，但如果其他人有更好的解决方案，请告诉我.

解决方案

在 Ruby 中，您可以使用 page.execute_script 来评估 JavaScript 变量(如果它可以从 Web 浏览器的范围内访问).看起来在 Java here.

这可能是一个更适合 JavaScript 单元测试框架的用例，例如 Jasmine.

I'm using Selenium WebDriver (Java) and TestNG to do some testing on a website I created. In this website, I also have JavaScript and in some of the functions, it returns values and also outputs values to the browser console through console.log().

I was wondering if there is an easy way for Selenium WebDriver to access some of this JavaScript information so I can perform assertions using TestNG.

I'm quite new to Selenium but I understand that you can do something like:

WebDriver driver = new ChromeDriver();
driver.findElement(By.id("btn")).click();

So is there anything similar I can do using WebDriver to read the JavaScript on the site?

---

Clarification

It looks like people are making the assumption that I'm trying to "execute" JavaScript code through Selenium.

Thats not the case. Instead, I'm trying to store already-defined JavaScript variable using Selenium.

Basically, I want Selenium to be able to grab the JavaScript variable's value, store it locally, and then do an assertion test on it.

---

Attempt 1

Say I have the following JS code for my website:

$(document).ready(function() {
    var foo = $(#"input-field-val").val();

    function returnFoo() {
        return foo;
    }
});

From what I've reading and understanding, in my seperate Selenium test file (Selenium.java), I should be able to do something like this?:

public class Selenium {
    WebDriver driver = new FirefoxDriver();
    JavascriptExecutor js = (JavascriptExecutor) driver;

    @Test
    public void testSample() {
        driver.get("www.mywebsite.com");
        js.executeScript("alert(returnFoo());");
    }
}

I do something similar to what's above but no alert box pops up. Instead, I get an error message:

Exception in thread "main" org.openqa.selenium.WebDriverException: ReferenceError: returnFoo is not defined

I'm pretty sure I'm not understanding what it means when its said that the JS variable

should not be part of a closure or local variable

I have also tried defining a global variable above the $(document).ready(function()... and setting is within function returnFoo() but still doesn't work.

---

Attempt 2

I've moved both foo and returnFoo() outside of the $(document).ready(function().... That has fixed ReferenceError message that I was getting in Attempt 1 above.

I hav also given foo a value so my JS code looks something like this:

var foo = "Selenium test run";

$(document).ready(function() {
...
});

function returnFoo() {
    return foo;
}

Now, I'm having a tough time assigning the return of returnFoo() to a local variable within my Selenium test. Here's what I've attempted:

public static void main(String[] args) {
        WebDriver driver = new FirefoxDriver();
        JavascriptExecutor js = (JavascriptExecutor) driver;

        driver.get("http://localhost:8080/HTML5TestApp/prod.html");
        Object val = js.executeScript("window.returnFoo();");
        System.out.println(val);
    } 

But the console display null instead of the actual value of "Selenium test run".

Attempt 2 - SOLUTION

It looks like if I do Object val = js.executeScript("alert(returnFoo());"); I get the value of foo.

---

SOLUTION

So here's the solution I've come up w/ to my problem thanks to the solution by Martin Foot below.

In my JavaScript file, I created a var and a setter/getter function like so:

index.js

var seleniumGlobal;

$(document).ready(function() {
...
)};

function setSG(toSet) {
    seleniumGlobal = toSet;
}

function getSG() {
    return seleniumGlobal;
}

SampleTest.java

// Do all the necessary imports

public class SampleTest {
    WebDriver driver = new FirefoxDriver();
    JavascriptExecutor js = (JavascriptExecutor) driver;

    @Test
    public void testPrintVal() {
        String sgVal = (String) js.executeScript("alert(getSG());");
        Assert.assertEquals("new value for seleniumGlobal", sgVal);
    }
}

So whenever some code in my JavaScript sets my seleniumGlobal variable through the setter method, I can call it through my Selenium test and do assertions on it.

This is probably not the most efficient way to do but if someone else has a better solution, please let me know.

解决方案

In Ruby you can use page.execute_script to evaluate a JavaScript variable (if it is accessable from the scope of the web browser). It looks like there is a similar method in Java here.

Edit: This might be a use case that is more suited to a JavaScript unit testing framework such as Jasmine.

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