[dotnet] Simplify and nullable annotate DriverFinder

dotnet/src/webdriver/Chromium/ChromiumDriver.cs

@@ -168,9 +168,9 @@ private static ICommandExecutor GenerateDriverServiceCommandExecutor(DriverServi
                 string fullServicePath = finder.GetDriverPath();
                 service.DriverServicePath = Path.GetDirectoryName(fullServicePath);
                 service.DriverServiceExecutableName = Path.GetFileName(fullServicePath);
-                if (finder.HasBrowserPath())
+                if (finder.TryGetBrowserPath(out string browserPath))
                 {
-                    options.BinaryLocation = finder.GetBrowserPath();
+                    options.BinaryLocation = browserPath;
                     options.BrowserVersion = null;
                 }
             }

dotnet/src/webdriver/DriverFinder.cs

@@ -19,10 +19,13 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.IO;
 using System.Text;
 
+#nullable enable
+
 namespace OpenQA.Selenium
 {
     /// <summary>
@@ -31,17 +34,16 @@ namespace OpenQA.Selenium
     /// </summary>
     public class DriverFinder
     {
-        private DriverOptions options;
+        private readonly DriverOptions options;
         private Dictionary<string, string> paths = new Dictionary<string, string>();
-        private const string BrowserPathKey = "browser_path";
-        private const string DriverPathKey = "driver_path";
 
         /// <summary>
         /// Initializes a new instance of the <see cref="DriverFinder"/> class.
         /// </summary>
+        /// <exception cref="ArgumentNullException">If <paramref name="options"/> is <see langword="null"/>.</exception>
         public DriverFinder(DriverOptions options)
         {
-            this.options = options;
+            this.options = options ?? throw new ArgumentNullException(nameof(options));
         }
 
         /// <summary>
@@ -52,7 +54,7 @@ public DriverFinder(DriverOptions options)
         /// </returns>
         public string GetBrowserPath()
         {
-            return BinaryPaths()[BrowserPathKey];
+            return BinaryPaths()[SeleniumManager.BrowserPathKey];
         }
 
         /// <summary>
@@ -63,14 +65,36 @@ public string GetBrowserPath()
         /// </returns>
         public string GetDriverPath()
         {
-            return BinaryPaths()[DriverPathKey];
+            return BinaryPaths()[SeleniumManager.DriverPathKey];
         }
 
+        /// <summary>
+        /// Gets whether there is a browser path for the given browser on this platform.
+        /// </summary>
+        /// <returns><see langword="true"/> if a browser path exists; otherwise, <see langword="false"/>.</returns>
         public bool HasBrowserPath()
         {
             return !string.IsNullOrWhiteSpace(GetBrowserPath());
         }
 
+        /// <summary>
+        /// Tries to get the browser path, as retrieved by Selenium Manager.
+        /// </summary>
+        /// <param name="browserPath">If the method returns <see langword="true"/>, the full browser path.</param>
+        /// <returns><see langword="true"/> if a browser path exists; otherwise, <see langword="false"/>.</returns>
+        public bool TryGetBrowserPath([NotNullWhen(true)] out string? browserPath)
+        {
+            string? path = GetBrowserPath();
+            if (!string.IsNullOrWhiteSpace(path))
+            {
+                browserPath = path;
+                return true;
+            }
+
+            browserPath = null;
+            return false;
+        }
+
         /// <summary>
         /// Invokes Selenium Manager to get the binaries paths and validates if they exist.
         /// </summary>
@@ -80,29 +104,33 @@ public bool HasBrowserPath()
         /// <exception cref="NoSuchDriverException">If one of the paths does not exist.</exception>
         private Dictionary<string, string> BinaryPaths()
         {
-            if (paths.ContainsKey(DriverPathKey) && !string.IsNullOrWhiteSpace(paths[DriverPathKey]))
+            if (paths.ContainsKey(SeleniumManager.DriverPathKey) && !string.IsNullOrWhiteSpace(paths[SeleniumManager.DriverPathKey]))
             {
                 return paths;
             }
+
             Dictionary<string, string> binaryPaths = SeleniumManager.BinaryPaths(CreateArguments());
-            string driverPath = binaryPaths[DriverPathKey];
-            string browserPath = binaryPaths[BrowserPathKey];
+            string driverPath = binaryPaths[SeleniumManager.DriverPathKey];
+            string browserPath = binaryPaths[SeleniumManager.BrowserPathKey];
+
             if (File.Exists(driverPath))
             {
-                paths.Add(DriverPathKey, driverPath);
+                paths.Add(SeleniumManager.DriverPathKey, driverPath);
             }
             else
             {
                 throw new NoSuchDriverException($"The driver path is not a valid file: {driverPath}");
             }
+
             if (File.Exists(browserPath))
             {
-                paths.Add(BrowserPathKey, browserPath);
+                paths.Add(SeleniumManager.BrowserPathKey, browserPath);
             }
             else
             {
                 throw new NoSuchDriverException($"The browser path is not a valid file: {browserPath}");
             }
+
             return paths;
         }
 
@@ -123,7 +151,7 @@ private string CreateArguments()
                 argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --browser-version {0}", options.BrowserVersion);
             }
 
-            string browserBinary = options.BinaryLocation;
+            string? browserBinary = options.BinaryLocation;
             if (!string.IsNullOrEmpty(browserBinary))
             {
                 argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --browser-path \"{0}\"", browserBinary);

dotnet/src/webdriver/Firefox/FirefoxDriver.cs

@@ -221,9 +221,9 @@ private static ICommandExecutor GenerateDriverServiceCommandExecutor(DriverServi
                 string fullServicePath = finder.GetDriverPath();
                 service.DriverServicePath = Path.GetDirectoryName(fullServicePath);
                 service.DriverServiceExecutableName = Path.GetFileName(fullServicePath);
-                if (finder.HasBrowserPath())
+                if (finder.TryGetBrowserPath(out string browserPath))
                 {
-                    options.BinaryLocation = finder.GetBrowserPath();
+                    options.BinaryLocation = browserPath;
                     options.BrowserVersion = null;
                 }
             }

dotnet/src/webdriver/SeleniumManager.cs

@@ -38,6 +38,9 @@ namespace OpenQA.Selenium
     /// </summary>
     public static class SeleniumManager
     {
+        internal const string DriverPathKey = "driver_path";
+        internal const string BrowserPathKey = "browser_path";
+
         private static readonly ILogger _logger = Log.GetLogger(typeof(SeleniumManager));
 
         private static readonly Lazy<string> _lazyBinaryFullPath = new(() =>
@@ -93,14 +96,14 @@ public static Dictionary<string, string> BinaryPaths(string arguments)
             var smCommandResult = RunCommand(_lazyBinaryFullPath.Value, argsBuilder.ToString());
             Dictionary<string, string> binaryPaths = new()
             {
-                { "browser_path", smCommandResult.BrowserPath },
-                { "driver_path", smCommandResult.DriverPath }
+                { BrowserPathKey, smCommandResult.BrowserPath },
+                { DriverPathKey, smCommandResult.DriverPath }
             };
 
             if (_logger.IsEnabled(LogEventLevel.Trace))
             {
-                _logger.Trace($"Driver path: {binaryPaths["driver_path"]}");
-                _logger.Trace($"Browser path: {binaryPaths["browser_path"]}");
+                _logger.Trace($"Driver path: {binaryPaths[DriverPathKey]}");
+                _logger.Trace($"Browser path: {binaryPaths[BrowserPathKey]}");
             }
 
             return binaryPaths;
@@ -214,9 +217,9 @@ public sealed record LogEntryResponse(string Level, string Message);
 
         public sealed record ResultResponse
         (
-            [property: JsonPropertyName("driver_path")]
+            [property: JsonPropertyName(SeleniumManager.DriverPathKey)]
             string DriverPath,
-            [property: JsonPropertyName("browser_path")]
+            [property: JsonPropertyName(SeleniumManager.BrowserPathKey)]
             string BrowserPath
         );
     }