Using Selenium.WebDriver's `By.Id` for finding elements fails when the ID starts with a numeral

[ChristoWolf]

Hi!

I have followed your Getting Started, but having troubles with finding existing elements using Selenium.WebDriver's By.Id.
I have not tried any other selector strategies yet.
The session that I am using is tied to the Root app.

Here is the exception thrown by OpenQA.Selenium.WebDriver.FindElement:

Exception thrown: 'OpenQA.Selenium.UnsupportedOperationException' in System.Private.CoreLib.dll: 'Selector strategy 'css selector' with value '#\34 b090d48-e3a5-4eb4-bd37-4bd62dfa6e5b' is not supported'
   at OpenQA.Selenium.WebDriver.UnpackAndThrowOnError(Response errorResponse, String commandToExecute)
   at OpenQA.Selenium.WebDriver.<ExecuteAsync>d__63.MoveNext()
   at OpenQA.Selenium.WebDriver.Execute(String driverCommandToExecute, Dictionary`2 parameters)
   at OpenQA.Selenium.WebDriver.FindElement(String mechanism, String value)
   at OpenQA.Selenium.By.<.ctor>b__11_0(ISearchContext context)
   at OpenQA.Selenium.By.FindElement(ISearchContext context)
   at OpenQA.Selenium.WebDriver.FindElement(By by)

The FlaUI.WebDriver output reads:

info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 POST http://127.0.0.1:4723/session/33131d2d-ee74-4618-a2cc-9cfcfe019e86/element - application/json;+charset=utf-8 76
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint 'FlaUI.WebDriver.Controllers.FindElementsController.FindElement (FlaUI.WebDriver)'
info: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[102]
      Route matched with {action = "FindElement", controller = "FindElements"}. Executing controller action with signature System.Threading.Tasks.Task`1[Microsoft.AspNetCore.Mvc.ActionResult] FindElement(System.String, FlaUI.WebDriver.Models.FindElementRequest) on controller FlaUI.WebDriver.Controllers.FindElementsController (FlaUI.WebDriver).
fail: FlaUI.WebDriver.WebDriverResponseExceptionFilter[0]
      Returning WebDriver error response with error code 'unsupported operation'
      FlaUI.WebDriver.WebDriverResponseException: Selector strategy 'css selector' with value '#\34 b090d48-e3a5-4eb4-bd37-4bd62dfa6e5b' is not supported
         at FlaUI.WebDriver.Services.ConditionParser.ParseCondition(ConditionFactory conditionFactory, String using, String value)
         at FlaUI.WebDriver.Controllers.FindElementsController.FindElementFrom(Func`1 startNode, FindElementRequest findElementRequest, Session session)
         at FlaUI.WebDriver.Controllers.FindElementsController.FindElement(String sessionId, FindElementRequest findElementRequest)
         at lambda_method14(Closure, Object)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.TaskOfActionResultExecutor.Execute(ActionContext actionContext, IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask`1 actionResultValueTask)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
info: Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor[1]
      Executing ObjectResult, writing value of type 'FlaUI.WebDriver.Models.ResponseWithValue`1[[FlaUI.WebDriver.Models.ErrorResponse, FlaUI.WebDriver, Version=0.3.3.0, Culture=neutral, PublicKeyToken=null]]'.
info: Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker[105]
      Executed action FlaUI.WebDriver.Controllers.FindElementsController.FindElement (FlaUI.WebDriver) in 0.9177ms
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint 'FlaUI.WebDriver.Controllers.FindElementsController.FindElement (FlaUI.WebDriver)'
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished HTTP/1.1 POST http://127.0.0.1:4723/session/33131d2d-ee74-4618-a2cc-9cfcfe019e86/element - 500 - application/json;+charset=utf-8 1.0363ms

4b090d48-e3a5-4eb4-bd37-4bd62dfa6e5b is the actual automation ID that I'm looking for, so I am confused by the leading 4 being escaped to #\34 by the Selenium client.

In any case, even if that ID would not exist, it is weird that FlaUI.WebDriver says that it does not support the CSS selector.

Used versions:

• FlaUI.WebDriver v0.3.3
• Selenium.WebDriver v4.29.0, also tried with v4.21.0
• The client code is wrapped on our side in .NET Standard 2.0 code.

Thanks for any help!

[ChristoWolf]

I guess you are expecting [\240-\377], see this regex, as based on the CSS grammar, but somehow the prefix #\34 is used for whatever reason, thus not matching of course.

[ChristoWolf]

It is due to this if block, the 4 gets escaped to \34 .

I have no deeper knowledge of CSS, so I don't know the reasoning for this.

Also, if it is possible to have such escaped sequences, why is that not covered by the regexes in the ConditionParser?