如何测试 img 标签是否存在? [英] How do I test if an img tag exists?

问题描述

如果我做 expect(img).not.toBe(null) 然后我得到一个错误:错误:期望使用 WebElement 参数调用，期望 Promise.您的意思是使用 .getText() 吗?.我不想在 img 中获取文本，我只想知道页面上是否存在标签.

if I do expect(img).not.toBe(null) then I get an error: Error: expect called with WebElement argment, expected a Promise. Did you mean to use .getText()?. I don't want to get the text inside an img, I just want to know if the tag exists on the page.

describe('company homepage', function() {
it('should have a captcha', function() {

    var driver = browser.driver;
    driver.get('http://dev.company.com/');

    var img =driver.findElement(by.id('recaptcha_image'));

    expect(img.getText()).not.toBe(null);
});
});

通过了，但我不确定它是否在测试正确的东西.将 id 更改为不存在的内容确实会失败.

Passes but I'm not sure it is testing the right thing. Changing the id to something that doesn't exist does fail.

如何在非角度应用上下文中使用量角器正确测试标签是否存在?

How do I properly test for a tag to exist with protractor in a non-angular app context?

推荐答案

Edit 2:

根据下面的 Coding Smackdown，量角器现在提供了更短的答案:

Per Coding Smackdown below, an even shorter answer is now available in protractor:

expect(element(by.id('recaptcha_image')).isPresent()).toBe(true);

编辑 1:

我今天发现了 isElementPresent()，对于我在下面描述的内容，它只是一个更具可读性的快捷方式.请参阅:http://www.protractortest.org/#/api

I discovered isElementPresent() today which is just a more readable shortcut for what I described below. See: http://www.protractortest.org/#/api

您的用法是:

driver.isElementPresent(by.id('recaptcha_image')).then(function(present){
    expect(present).toBe(false);
})

<小时>

旧答案(这可行，但以上对读者更友好)

---

Old answer (this works but the above is more reader friendly)

通常，如果您不确定标签是否存在，您应该使用 findElements(或 $$，它是 css 中 findElements 的别名).然后测试数组长度.FindElement(和 $)如果找不到元素只会抛出错误.

In general you should use findElements (or $$ which is an alias for findElements by css) if you're not sure a tag will be there. Then test for the array length. FindElement (and $) will just throw an error if it cant find the element.

因此代替

var img =driver.findElement(by.id('recaptcha_image'));

expect(img.getText()).not.toBe(null);

使用:

driver.findElements(by.id('recaptcha_image')).then(function(array){
    expect(array.length).not.toBe(0);
})

此外，getText() 返回一个 promise，这就是您收到该错误的原因.

Also, getText() returns a promise which is why you're getting that error.

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