[🐛 Bug]: [dotnet] Unable to set dictionary to the UnhandledPromptBehavior option

[JuliaNaumetsss]

Description

Starting from Chrome 137 it's unable to manage browser prompts (alerts) using BiDi driver. Issues on ChromeDriver were created, but they were closed as intendent behavior:
https://issues.chromium.org/issues/425390962
https://issues.chromium.org/issues/428153658

Based on the specification we should provide unhandledPromptBehavior as a dictionary. Based on the comment in the issue it's possible to do it for java, using MutableCapabilities, but I didn't find any solution for c#.

In my project I use Selenium 4.23 + .net 4.7.2. I tried the following code:

var promptBehavior = new Dictionary<string, string>
{
				{"alert", "ignore"},
				{"confirm", "ignore"},
				{"prompt", "ignore"},
				{"beforeUnload", "ignore"},
				{"default", "ignore"}
};
options.AddAdditionalOption("unhandledPromptBehavior", promptBehavior);

But exception is thrown : System.ArgumentException: 'There is already an option for the unhandledPromptBehavior capability. Please use the UnhandledPromptBehavior property instead.
Parameter name: capabilityName'

I can't set dictionary to the options.UnhandledPromptBehavior either, because it's waiting for the UnhandledPromptBehavior map (for example, UnhandledPromptBehavior.Ignore).

Before Selenium 4 we were able to set capabilities via DesiredCapabilities, but in Selenium 4.23 this class is internal.

So, it seems, that there are no possibility to set dictionary to the unhandledPromptBehavior option when starting Chrome Driver.

Note: everything worked fine till Chrome 137.

Reproducible Code

1. Start Chrome 137+ using BiDi ChromeDriver and use the following Chrome options:
options.UseWebSocketUrl = true;
options.UnhandledPromptBehavior = UnhandledPromptBehavior.Ignore;

Actual result: browser alert is not shown
Expected result: alert is shown, because UnhandledPromptBehavior was set to Ignore. 

Possible reason: value for UnhandledPromptBehavior is not a dictionary.

[selenium-ci]

@JuliaNaumetsss, thank you for creating this issue. We will troubleshoot it as soon as we can.

Selenium Triage Team: remember to follow the Triage Guide

[github-actions]

⚠️ You reported using Selenium version 4.23.0, but the latest release is 4.34.

Please verify that this issue still occurs with the latest version. If it no longer applies, you can close this issue or update your comment.

This issue will be marked "awaiting answer" and may be closed automatically if no response is received.

[cgoldberg]

Please also add a title to this issue.

[nvborisenko]

Interesting, just subscribing on it..