[dotnet] Annotate nullability on ChromiumOptions

[RenderMichael]

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Motivation and Context

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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PR Type

Enhancement, Bug fix

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Description

• Annotated nullability for properties and methods in ChromiumOptions.

• Replaced mutable fields with readonly where applicable.

• Added exception handling for invalid arguments in public methods.

• Refactored helper methods to use static and nullable parameters.

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Changes walkthrough 📝

Relevant files

Enhancement

ChromiumOptions.cs Added nullability annotations and refactored `ChromiumOptions`. dotnet/src/webdriver/Chromium/ChromiumOptions.cs Enabled nullable reference types with #nullable enable. Annotated properties and methods with nullable types. Replaced mutable fields with readonly for immutability. Added exception handling for invalid arguments in public methods. Refactored helper methods to use static and nullable parameters. +93/-102

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[qodo-code-review]

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 AddArguments() and AddEncodedExtensions() methods still create a new List unnecessarily when calling the overloaded method this.AddEncodedExtensions((IEnumerable<string>)extensions); Validation The EnableMobileEmulation method accepts null deviceSettings but does not validate other properties like Width, Height, PixelRatio for valid values public void EnableMobileEmulation(ChromiumMobileEmulationDeviceSettings? deviceSettings) {

[qodo-code-review]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Possible issue	Validate individual collection elements The AddArguments method should validate each individual argument in the collection for null/empty values, not just the collection itself, to prevent invalid arguments from being added. dotnet/src/webdriver/Chromium/ChromiumOptions.cs [182-190] public void AddArguments(IEnumerable<string> argumentsToAdd) { if (argumentsToAdd == null) { throw new ArgumentNullException(nameof(argumentsToAdd), "Arguments to add cannot be null"); } + foreach (string arg in argumentsToAdd) + { + if (string.IsNullOrEmpty(arg)) + { + throw new ArgumentException("Individual arguments cannot be null or empty"); + } + } this.arguments.AddRange(argumentsToAdd); } Apply this suggestion Suggestion importance[1-10]: 7 Why: The suggestion adds important input validation to prevent invalid arguments from being added to the collection, which could cause issues later when the arguments are used. This improves robustness and error handling.	7
	Add null check before access The EnableMobileEmulation method should validate that the device settings object is not null before accessing its properties to avoid potential null reference exceptions. dotnet/src/webdriver/Chromium/ChromiumOptions.cs [407-413] public void EnableMobileEmulation(ChromiumMobileEmulationDeviceSettings? deviceSettings) { this.mobileEmulationDeviceName = null; - if (deviceSettings != null && string.IsNullOrEmpty(deviceSettings.UserAgent)) + if (deviceSettings == null) + { + this.mobileEmulationDeviceSettings = null; + return; + } + + if (string.IsNullOrEmpty(deviceSettings.UserAgent)) { throw new ArgumentException("Device settings must include user agent string", nameof(deviceSettings)); } this.mobileEmulationDeviceSettings = deviceSettings; } Apply this suggestion Suggestion importance[1-10]: 5 Why: The suggestion improves null handling by separating the null check from the UserAgent validation, making the code more maintainable and clearer in its intent. However, the original code already handled nulls safely.	5

[RenderMichael]

I am not adding null checks to:

• Each string element of AddArguments
• Each string element of AddExcludedArgument
• Each string element of AddExtensions
• Each string element of AddEncodedExtensions
• Value preferenceValue parameter of AddUserProfilePreference
• Value preferenceValue parameter of AddLocalStatePreference
• Each string element of AddWindowTypes
• Value optionValue parameter of AddAdditionalChromiumOption

This is to avoid breaking users. There is no downstream issue on the C# side of passing in null (it will just get serialized normally). If there are exceptions on the backend, let users see it. We will add a null warning, but not throw an exception on our side here.