Selenium WebDriver for .Net does not work IE11 when WebComponents.js present

Expected Behavior

WebDriver should be able to find an element on page.

Actual Behavior

WebDriver can’t find an element on page if WebComponents.js is loaded and the browser is IE11. This happens at least for methods By.XPath and By.CssSelector.

The below test project tries Firefox and IE11 driver. Only IE11 fails on this.

My environment is Windows 10 64-bit, using Selenium for .Net.

Versions used: NUnit 2.6.4, NUnitTestAdapter 2.0.0, Selenium.Support 2.52.0, Selenium.WebDriver 2.52.0, WebDriver.IEDriverServer.win64 2.44, WebComponents.js 0.7.21

Steps to reproduce

I have created a test project to recreate the issue: https://github.com/warpech/SeleniumTest

• Test file: https://github.com/warpech/SeleniumTest/blob/gh-pages/UnitTest1.cs
• HTML that works: https://github.com/warpech/SeleniumTest/blob/gh-pages/wwwroot/regular.html
• HTML that doesn’t work: https://github.com/warpech/SeleniumTest/blob/gh-pages/wwwroot/webcomponents.html

For example, the following test:

IWebElement element = wait.Until(driver => driver.FindElement(By.XPath("(//h1)[1]")));

Fails with error:

Test Name:  Polyfill_BodyElementExists
Test FullName:  SeleniumTests.MarcinNunit("internet explorer").Polyfill_BodyElementExists
Test Source:    C:\www\warpech\SeleniumTest\UnitTest1.cs : line 78
Test Outcome:   Failed
Test Duration:  0:00:18.645

Result StackTrace:  
at OpenQA.Selenium.Support.UI.DefaultWait`1.ThrowTimeoutException(String exceptionMessage, Exception lastException)
at OpenQA.Selenium.Support.UI.DefaultWait`1.Until[TResult](Func`2 condition)
at SeleniumTests.MarcinNunit.Polyfill_BodyElementExists() in C:\www\warpech\SeleniumTest\UnitTest1.cs:line 83
--NoSuchElementException
at OpenQA.Selenium.Remote.RemoteWebDriver.UnpackAndThrowOnError(Response errorResponse)
at OpenQA.Selenium.Remote.RemoteWebDriver.Execute(String driverCommandToExecute, Dictionary`2 parameters)
at OpenQA.Selenium.Remote.RemoteWebDriver.FindElement(String mechanism, String value)
at OpenQA.Selenium.Remote.RemoteWebDriver.FindElementByXPath(String xpath)
at OpenQA.Selenium.By.<>c__DisplayClasse.<XPath>b__c(ISearchContext context)
at OpenQA.Selenium.By.FindElement(ISearchContext context)
at OpenQA.Selenium.Remote.RemoteWebDriver.FindElement(By by)
at SeleniumTests.MarcinNunit.<>c.<Polyfill_BodyElementExists>b__10_0(IWebDriver driver) in C:\www\warpech\SeleniumTest\UnitTest1.cs:line 83
at OpenQA.Selenium.Support.UI.DefaultWait`1.Until[TResult](Func`2 condition)
Result Message: 
OpenQA.Selenium.WebDriverTimeoutException : Timed out after 10 seconds
  ----> OpenQA.Selenium.NoSuchElementException : Unable to find element with xpath == (//h1)[1]

[jimevans]

This polyfill overrides basic DOM functionality, and causes JavaScript execution to return a wrapper object instead of the actual DOM node. Since IE doesn’t have a native XPath-over-HTML engine, finding elements by XPath is done using a JavaScript XPath execution engine. Additionally, the automation atoms for finding elements are written in JavaScript, and that means finding by CSS selector similarly uses JavaScript, via querySelector(). As long as this is the case, and the polyfill is returning a wrapped JavaScript object instead of the actual DOM node, findElement() will not work for the IE driver.

[diemol]

Closing this since the thread has been stale and also thanks to the explanation given here.