使用CSS元素来检查元素是否存在于量角器中(Use element by css to check if element exists in Protractor)

 在量角器端到端测试中，我想检查一个元素是否存在使用元素（by.css（...）），我的代码： 
 
var myElement = element(by.css('.elementClass'));
expect(myElement).toBeUndefined;
 
 这个测试失败了，它说： 
 
    Expected { locator_ : { using : 'css selector', value : 'div[ng-switch-
    when="resultNav"]' }, parentElementFinder_ : null, opt_actionResult_ :
    undefined, opt_index_ : undefined, click : Function, sendKeys : Function, 
getTagName : Function, getCssValue : Function, getAttribute : Function, getText
 : Function, getSize : Function, getLocation : Function, isEnabled : Function, 
isSelected : Function, submit : Function, clear : Function, isDisplayed : 
Function, getOuterHtml : Function, getInnerHtml : Function, toWireValue : 
Function } to be undefined.
 
 之后，我尝试使用承诺： 
 
element(by.css('.elementClass')).then( functtion(data) {
    expect(data.getText()).toBeUndefined();
});
 
 这会导致错误： 
 
Error: No element found using locator By.CssSelector(...)
 
 是的，我知道没有找到任何元素，但是如何使用元素（by.css（...））创建工作测试？ 
 
 有谁知道如何做到这一点？ 或者是元素（by.css（））而不是在这里使用的方法？ 

In a protractor end to end test, I want to check if an element exist using element(by.css(...)), my code:
 
var myElement = element(by.css('.elementClass'));
expect(myElement).toBeUndefined;
 
This test fails, it says:
 
    Expected { locator_ : { using : 'css selector', value : 'div[ng-switch-
    when="resultNav"]' }, parentElementFinder_ : null, opt_actionResult_ :
    undefined, opt_index_ : undefined, click : Function, sendKeys : Function, 
getTagName : Function, getCssValue : Function, getAttribute : Function, getText
 : Function, getSize : Function, getLocation : Function, isEnabled : Function, 
isSelected : Function, submit : Function, clear : Function, isDisplayed : 
Function, getOuterHtml : Function, getInnerHtml : Function, toWireValue : 
Function } to be undefined.
 
After that I tried to use a promise:
 
element(by.css('.elementClass')).then( functtion(data) {
    expect(data.getText()).toBeUndefined();
});
 
This results in an error:
 
Error: No element found using locator By.CssSelector(...)
 
Yes, I know that no element will be found, but how can I create a working test using element(by.css(...))?
 
Does anyone know how to achieve this? or is element(by.css()) not the method to use here?

原文：https://stackoverflow.com/questions/28024342