[dotnet] Annotate nullability for DriverService and chromium/safari services

[RenderMichael]

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Description

Adds nullability annotations to DriverService, as well as some child types SafariDriverService and ChromiumDriverService.

Motivation and Context

Contributes to #14640

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

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Description

• Added nullability annotations to DriverService and derived classes.

• Refactored properties in ChromiumDriverService to use auto-properties.

• Improved code readability and safety with nullable reference types.

• Updated event handling and initialization logic in DriverService.

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Changes walkthrough 📝

Relevant files

Enhancement

ChromiumDriverService.cs Refactored `ChromiumDriverService` with nullability annotations dotnet/src/webdriver/Chromium/ChromiumDriverService.cs Enabled nullable reference types for the file. Refactored properties to use auto-properties with default values. Updated command-line argument construction for null-safe properties. Simplified obsolete property handling and improved readability. +33/-68  DriverService.cs Enhanced `DriverService` with nullability and refactoring dotnet/src/webdriver/DriverService.cs Enabled nullable reference types for the file. Refactored fields to properties with default values. Updated event handling with null-safe invocation. Improved initialization and process management logic. +40/-80  SafariDriverService.cs Updated `SafariDriverService` with nullability and refactoring dotnet/src/webdriver/Safari/SafariDriverService.cs Enabled nullable reference types for the file. Updated constructor parameters to nullable types. Refactored properties to use expression-bodied members. Improved default service creation logic with null safety. +7/-5

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PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Null Reference The ServiceUrl property constructs a new Uri without checking if HostName is null, which could lead to a NullReferenceException. get { string url = string.Format(CultureInfo.InvariantCulture, "http://{0}:{1}", this.HostName, this.Port); return new Uri(url); } } Error Handling The Start() method throws a generic WebDriverException without including the original exception details when service initialization fails. throw new WebDriverException($"Cannot start the driver service on {this.ServiceUrl}"); }

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Possible issue	Add proper null checking when processing file paths to prevent runtime errors Add null check for driverPath before using Path.GetDirectoryName() since it could return null for invalid paths. Consider throwing an ArgumentException if path is invalid. dotnet/src/webdriver/Safari/SafariDriverService.cs [112] -driverPath = Path.GetDirectoryName(driverPath)!; +var dirPath = Path.GetDirectoryName(driverPath); +if (dirPath == null) +{ + throw new ArgumentException("Invalid driver path specified", nameof(driverPath)); +} +driverPath = dirPath; Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion addresses a potential runtime error by adding proper null checks for directory paths. This is important for robustness and error handling, preventing crashes when invalid paths are provided.	8
	Add null checks when accessing nested properties to prevent null reference exceptions Add null check for response.Content.Headers.ContentType before accessing its MediaType property to prevent potential NullReferenceException. dotnet/src/webdriver/DriverService.cs [195] -isInitialized = response.StatusCode == HttpStatusCode.OK && response.Content.Headers.ContentType is { MediaType: string mediaType } && mediaType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase); +isInitialized = response.StatusCode == HttpStatusCode.OK && + response.Content?.Headers?.ContentType?.MediaType is string mediaType && + mediaType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase); Apply this suggestion Suggestion importance[1-10]: 7 Why: The suggestion improves code safety by adding proper null checks for nested properties in the HTTP response handling. This prevents potential NullReferenceExceptions in production environments.	7

[nvborisenko]

In general any field here can be null. Later all fields go to executable as command parameters (if not null or empty).

The principle question:

driverService.PortServerAddress = null; // am I doing right as an user? or exception?

I guess any parameter in this class can be nullable.

TIP: AndroidDebugBridgePort also can be nullable, previously -1 indicated it is not set (as I understand the logic).

[RenderMichael]

Good points! Let me update the code.