protractor端对端测试出现：Element not vi

这在使用selenium自动测试中是一个相当常见的问题。
可能的原因以及解决办法有几种：
1.make sure the element you want to click is actually visible. Sometimes you need to make extra actions on a page to make the element visible. For example, open up a dropdown for an option to appear or open menu for submenu to appear
2.wait for the visibility of the element:

var EC = protractor.ExpectedConditions;
var mumbaiCity = element(by.id('mumbaiCity'));
browser.wait(EC.visibilityOf(mumbaiCity), 5000);
mumbaiCity.click();

3.there is an another element with the same id that is actually invisible. In this case, you need to improve your locator to match this specific element. For instance:

element(by.css(".city-checkbox #mumbaiCity")).click();
element(by.css(".city-checkbox input[ng-click*=Mumbai]")).click();

4.Or, if you got multiple elements matching the same locator - you can "filter" out a visible element:

var mumbaiCity = element.all(by.id('mumbaiCity')).filter(function (elm) {
    return elm.isDisplayed().then(function (isDisplayed) {
        return isDisplayed;
    });
}).first();
mumbaiCity.click();

5.move to element and then click via browser.actions():

var mumbaiCity = element(by.id('mumbaiCity'));
browser.actions().mouseMove(mumbaiCity).click().perform();

6.scroll into view of the element and then click:

var mumbaiCity = element(by.id('mumbaiCity'));
browser.executeScript("arguments[0].scrollIntoView();", mumbaiCity.getWebElement());
mumbaiCity.click();

7.click via javascript (beware of the differences though):

var mumbaiCity = element(by.id('mumbaiCity'));
browser.executeScript("arguments[0].click();", mumbaiCity.getWebElement());

8.sometimes, you just need to maximize the browser window:

browser.driver.manage().window().maximize();

参考自：stackoverflow