[py]: fix WebView2 and target issues related to CDP and BiDi

[nxs7]

User description

💥 What does this PR do?

This PR addresses two issues related to the CDP and BiDi functionalities in the selenium.webdriver.remote.webdriver.WebDriver class.

• WebView2 Identification
  • In WebDriver._get_cdp_details, the current implementation does not properly account for WebView2 when determining whether the browser is Edge. This causes crashes when using CDP or BiDi features with WebView2-based applications.
• Target locating
  • In WebDriver.start_devtools and WebDriver.bidi_connection, the current implementation hard codes the attachment to the first target returned by the CDP method Target.getTargets, resulting in the following two issues:
    • If multiple pages are open, a random page is attached;
    • If only one page is open but it contains service workers or iframes, one of these may be attached instead, causing crashes in subsequent CDP method calls.

Minimal reproduction code for target locating:
Case 1: Multiple pages

from selenium import webdriver
driver = webdriver.Chrome()
driver.get("https://www.google.com/")
driver.switch_to.new_window()
driver.get("https://www.facebook.com/")
devtools, connection = driver.start_devtools()
current_index, entries = connection.execute(devtools.page.get_navigation_history())
print(entries[current_index].url) # Randomly prints "https://www.google.com/" or "https://www.facebook.com/"
driver.quit()

Case 2: Single page with service workers or iframes

from selenium import webdriver
driver = webdriver.Chrome()
driver.get("https://www.youtube.com/")
devtools, connection = driver.start_devtools()
connection.execute(devtools.page.get_navigation_history()) # May crash with "method not found" error
driver.quit()

🔧 Implementation Notes

To address the target locating issue, this PR iterates through the targets returned, matching the target ID with the handle of the current window.

💡 Additional Considerations

In future implementations, the start_devtools and bidi_connection may receive an optional parameter specifying the window handle, enabling more precise attachment to a specific window.

🔄 Types of changes

• Bug fix (backwards compatible)

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PR Type

Bug fix

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Description

• Fix WebView2 browser identification in CDP connection setup

• Fix target selection to use current window handle instead of first target

• Prevent crashes when multiple pages or service workers are present

• Ensure correct target attachment for CDP and BiDi connections

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Diagram Walkthrough

flowchart LR
  A["WebDriver CDP/BiDi Request"] --> B["Get Available Targets"]
  B --> C["Match Target ID with Current Window Handle"]
  C --> D["Attach to Correct Target"]
  E["WebView2 Detection"] --> F["Use ms:edgeOptions for WebView2"]

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File Walkthrough

	Relevant files
Bug fix	webdriver.py Fix target selection and WebView2 support                                py/selenium/webdriver/remote/webdriver.py Replace hardcoded first target selection with window handle matching Add WebView2 browser name check for Edge options Apply fix to both start_devtools and bidi_connection methods +9/-3

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[CLAassistant]

All committers have signed the CLA.

[qodo-merge-pro]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 3 🔵🔵🔵⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Possible Issue The target matching logic may fail if no target matches the current window handle, leaving target_id undefined and causing a NameError when passed to attach_to_target. A fallback mechanism or error handling should be considered. for target in targets: if target.target_id == self.current_window_handle: target_id = target.target_id break Logic Error The conditional logic for Edge browser detection is malformed. The elif condition should include the assignment to debugger_address within its block, but the current structure places it outside the conditional. elif self.caps.get("browserName") == "MicrosoftEdge" or self.caps.get("browserName") == "webview2": debugger_address = self.caps.get("ms:edgeOptions").get("debuggerAddress")

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Add fallback for undefined target_id Add a fallback mechanism when no target matches the current window handle. Without this, target_id could remain undefined if no matching target is found, leading to a runtime error. py/selenium/webdriver/remote/webdriver.py [1214-1217] +target_id = None for target in targets: if target.target_id == self.current_window_handle: target_id = target.target_id break +if target_id is None: + target_id = targets[0].target_id if targets else None Apply / Chat Suggestion importance[1-10]: 8 __ Why: The suggestion correctly identifies a potential UnboundLocalError if no matching target is found in the loop, which would leave target_id undefined and cause a runtime error.	Medium
Update

[navin772]

@nxs7 Thanks for the contribution! The changes look good, have you tested this with webview2 and does it works as intended? How can I test it?

[nxs7]

Hello. Given that you're a Selenium developer, I hope it's not too bold to assume you already have Visual Studio with C# installed :)

Microsoft provides several WebView2 samples, including the MicrosoftEdge/WebView2Samples repository. Please clone the repository and navigate to either GettingStartedGuides/WPF_GettingStarted or GettingStartedGuides/WinForms_GettingStarted, then build the project. You may want to update the target framework first, as it is somewhat outdated.

After building the application, you can use the following code to reproduce the issue.

from selenium import webdriver
options = webdriver.EdgeOptions()
options.use_webview = True
options.binary_location = <path_to_your_application>
driver = webdriver.Edge(options=options)
driver.start_devtools() # Crashes with "variable not associated with value" error
driver.quit()

[navin772]

@nxs7 I was able to get this working on a windows machine and with your fix, the mentioned error is no longer present.

But I wasn't able to get start_devtools to work with webview2 completely, it got stuck/hanged at this line:

selenium/py/selenium/webdriver/remote/webdriver.py

Line 1213 in 0a931d7

targets = self._websocket_connection.execute(self._devtools.target.get_targets())

After digging a bit, I found that the websocket connection was getting closed (this behavior was flaky), adding a few retries did solve it. Note that this happens only with webview2 and not normal chrome/edge devtools connection.

Did you noticed any such issues with selenium and webview2?

[nxs7]

Nope, I've tested this on multiple machines with both WPF_GettingStarted and WinForms_GettingStarted, as well as several other real-world WebView2 applications. In all cases, the start_devtools returned successfully, and I was able to use the returned devtools and connection to execute CDP methods and get correct results. Could you try testing it on different machines to see if the issue persists?

[navin772]

It is now working consistently after a restart! Spent a good amount of time debugging the previous error :(

[navin772]

LGTM!

[cgoldberg]

1 tiny nitpick requested... other than that LGTM.

@nxs7 please make that small change and we will merge this.
thanks!