How to find unique selectors for elements on pages with ExtJS for use with Selenium?

Another victim of ExtJS UI automation testing, here are my tips specifically for testing ExtJS. (However, this won't answer the question described in your title)

Tip 1: Don't ever use unreadable XPath like /div[4]/div[3]/div[4]/div/div/div/span[2]/span. One tiny change of source code may lead to DOM structure change. This will cause huge maintenance costs.

Tip 2: Take advantage of meaningful auto-generated partial ids and class names.

For example, this ExtJS grid example: By.cssSelector(".x-grid-view .x-grid-table") would be handy. If there are multiple of grids, try index them or locate the identifiable ancestor, like By.cssSelector("#something-meaningful .x-grid-view .x-grid-table").

Tip 3: Create meaningful class names in the source code. ExtJS provides cls and tdCls for custom class names, so you can add cls:'testing-btn-cancel' in your source code, and get it by By.cssSelector(".testing-btn-cancel").

Tip3 is the best and the final one. If you don't have access the source code, talk to your manager, Selenium UI automation should really be a developer job for someone who can modify the source code, rather than a end-user-like tester.

I would recommend using CSS in this instance by doing By.cssSelector("span[id^='ext-gen'])

The above statement means "select a span element with an id that starts with ext-gen". (If it needs to be more specific, you can reply, and I'll see if I can help you).

Alternatively, if you want to use XPath, look at this answer: Xpath for selecting html id including random number

Although it is not desired in some cases as mentioned above, you can parse through the elements and generate xpath ids.

import java.util.LinkedHashMap;import java.util.List;import java.util.Map;import org.openqa.selenium.By;import org.openqa.selenium.WebDriver;import org.openqa.selenium.WebElement;public class XPATHDriverWrapper {Map xpathIDToWebElementMap = new LinkedHashMap();Map webElementToXPATHIDMap = new LinkedHashMap();public XPATHDriverWrapper(WebDriver driver){    WebElement htmlElement = driver.findElement(By.xpath("/html"));    iterateThroughChildren(htmlElement, "/html");}private void iterateThroughChildren(WebElement parentElement, String parentXPATH) {    Map siblingCountMap = new LinkedHashMap();    List childrenElements = parentElement.findElements(By.xpath(parentXPATH+"/*"));    for(int i=0;i<childrenElements.size(); i++) {        WebElement childElement = childrenElements.get(i);        String childTag = childElement.getTagName();        String childXPATH = constructXPATH(parentXPATH, siblingCountMap, childTag);        xpathIDToWebElementMap.put(childXPATH, childElement);        webElementToXPATHIDMap.put(childElement, childXPATH);        iterateThroughChildren(childElement, childXPATH);//          System.out.println("childXPATH:"+childXPATH);    }}public WebElement findWebElementFromXPATHID(String xpathID) {    return xpathIDToWebElementMap.get(xpathID);}public String findXPATHIDFromWebElement(WebElement webElement) {    return webElementToXPATHIDMap.get(webElement);}private String constructXPATH(String parentXPATH,        Map siblingCountMap, String childTag) {    Integer count = siblingCountMap.get(childTag);    if(count == null) {        count = 1;    } else {        count = count + 1;    }    siblingCountMap.put(childTag, count);    String childXPATH = parentXPATH + "/" + childTag + "[" + count + "]";    return childXPATH;}}

Another wrapper to generate ids from Document is posted at: http://scottizu.wordpress.com/2014/05/12/generating-unique-ids-for-webelements-via-xpath/