[dotnet] Simplify and nullable annotate DriverFinder

[RenderMichael]

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Simplify and nullable annotate DriverFinder

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, Bug fix

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Description

• Simplified and nullable-annotated DriverFinder class.

• Introduced TryGetBrowserPath method for safer browser path retrieval.

• Replaced dictionary-based paths with SeleniumManagerPaths record.

• Improved error handling and nullability checks in driver and browser path logic.

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Changes walkthrough 📝

Relevant files

Enhancement

ChromiumDriver.cs Updated browser path handling in ChromiumDriver                    dotnet/src/webdriver/Chromium/ChromiumDriver.cs Replaced HasBrowserPath with TryGetBrowserPath for safer path retrieval. Updated logic to handle nullable browser paths. +2/-2      DriverFinder.cs Simplified and enhanced `DriverFinder` implementation        dotnet/src/webdriver/DriverFinder.cs Added nullability annotations and checks. Replaced dictionary with SeleniumManagerPaths for path storage. Introduced TryGetBrowserPath method for safer path retrieval. Improved error handling for invalid paths. +43/-25  FirefoxDriver.cs Updated browser path handling in FirefoxDriver                      dotnet/src/webdriver/Firefox/FirefoxDriver.cs Replaced HasBrowserPath with TryGetBrowserPath for safer path retrieval. Updated logic to handle nullable browser paths. +2/-2      SeleniumManager.cs Refactored SeleniumManager to use `SeleniumManagerPaths`  dotnet/src/webdriver/SeleniumManager.cs Replaced dictionary-based paths with SeleniumManagerPaths record. Improved logging and error handling for path retrieval. Updated method signatures to use SeleniumManagerPaths. +17/-17

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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 Error Handling The BinaryPaths method throws NoSuchDriverException for invalid browser path, but this may be too strict since browser path is optional in some cases. Consider making browser path validation conditional. if (!File.Exists(binaryPaths.BrowserPath)) { throw new NoSuchDriverException($"The browser path is not a valid file: {binaryPaths.BrowserPath}"); }

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Possible issue	Prevent null reference exception Add null check for binaryPaths.BrowserPath before validating file existence to prevent NullReferenceException. The browser path might be null in some cases. dotnet/src/webdriver/DriverFinder.cs [119-122] -if (!File.Exists(binaryPaths.BrowserPath)) +if (!string.IsNullOrEmpty(binaryPaths.BrowserPath) && !File.Exists(binaryPaths.BrowserPath)) { throw new NoSuchDriverException($"The browser path is not a valid file: {binaryPaths.BrowserPath}"); } Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion addresses a critical null reference safety issue that could cause runtime crashes. The browser path validation should indeed check for null/empty values before attempting to verify file existence.	8
	Handle null browser path safely Add null check for path before accessing it in GetBrowserPath() to prevent potential NullReferenceException when accessing BrowserPath property. dotnet/src/webdriver/DriverFinder.cs [56-59] public string GetBrowserPath() { - return BinaryPaths().BrowserPath; + var paths = BinaryPaths(); + return paths.BrowserPath ?? string.Empty; } Apply this suggestion Suggestion importance[1-10]: 7 Why: The suggestion improves null safety by handling potential null browser paths gracefully, preventing runtime exceptions. This is particularly important as the code already shows signs of null-safety concerns with nullable annotations.	7

[nvborisenko]

Please let me postpone it, DriverFinder is strange for me (in terms of nullability).

[RenderMichael]

@nvborisenko It took me some time to figure out, but I found out the reason: when no browser exists, Selenium Manager will return an empty string as the value.