Are XPath selectors properly supported in BiDi mode? #14275

aDifferentUser · 2025-03-12T12:38:07Z

aDifferentUser
Mar 12, 2025

We currently use WDIO v9 in "classic mode" and want to switch over to BiDi mode. The main reason for this is to benefit from the new “Automatic Shadow Root Piercing”.

When I run our tests in BiDi mode, the log gets flooded with these messages:
[0-0] 2025-03-12T10:54:45.253Z WARN webdriverio: Failed to execute browser.browsingContextLocateNodes({ ... }) due to Error: WebDriver Bidi command "browsingContext.locateNodes" failed with error: unknown error - Unexpected error in selector script: NotSupportedError: Failed to execute 'evaluate' on 'XPathExpression': The node provided is '#document-fragment', which is not a valid context node type., falling back to regular WebDriver Classic command

This message gets logged every time a XPath selector gets evaluated when there is a shadow root present on the test page. Even the targeted element is not inside a shadow root.

Is this expected behaviour?
I could not find any documentation or reported issue about this.

christian-bromann · 2025-03-12T17:43:25Z

christian-bromann
Mar 12, 2025
Maintainer

Thanks for raising the issue @aDifferentUser , any chance you can create a reproduction case?

0 replies

aDifferentUser · 2025-03-13T10:32:50Z

aDifferentUser
Mar 13, 2025
Author

Hi @christian-bromann
Thanks for your fast response.

I can reproduce it with this simple example using Chrome 134:
index.html

<html lang="en">
    <head>
        <title>Test</title>
    </head>
    <body>
        <div id="shadowHost"></div>
        <script>
            const shadow = document.querySelector('#shadowHost').attachShadow({mode: "open"});
            shadow.innerHTML = '<p id="test">Text in Shadow DOM</p>';
        </script>
    </body>
</html>

spec.ts

describe('BiDi test', () => {
    it('CSS selector', async () => {
        expect(await $('#test').getText()).toBe('Text in Shadow DOM');
    });
    it('XPath selector', async () => {
        expect(await $('//*[@id="test"]').getText()).toBe('Text in Shadow DOM');
    });
});

The CSS selector works as expected. But the XPath selector does not work at all and raises the metioned warning before failing:

[chrome 134.0.6998.89 windows #0-0] BiDi test
[chrome 134.0.6998.89 windows #0-0]    ✓ CSS selector
[chrome 134.0.6998.89 windows #0-0]    ✖ XPath selector
[chrome 134.0.6998.89 windows #0-0]
[chrome 134.0.6998.89 windows #0-0] 1 passing (10.4s)
[chrome 134.0.6998.89 windows #0-0] 1 failing
[chrome 134.0.6998.89 windows #0-0]
[chrome 134.0.6998.89 windows #0-0] 1) BiDi test XPath selector
[chrome 134.0.6998.89 windows #0-0] Can't call getText on element with selector "//*[@id="test"]" because element wasn't found
[chrome 134.0.6998.89 windows #0-0] Error: Can't call getText on element with selector "//*[@id="test"]" because element wasn't found
[chrome 134.0.6998.89 windows #0-0]     at Context.<anonymous> (c:\Workspace\.....\bidi.spec.ts:6:16)

0 replies

christian-bromann · 2025-03-24T07:58:23Z

christian-bromann
Mar 24, 2025
Maintainer

@aDifferentUser I created an issue for this. Any contributions would be much appreciated.

0 replies

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