added logPath property

dotnet/src/webdriver/Firefox/FirefoxDriverService.cs

@@ -39,6 +39,7 @@ public sealed class FirefoxDriverService : DriverService
         private string host = string.Empty;
         private string browserCommunicationHost = string.Empty;
         private FirefoxDriverLogLevel loggingLevel = FirefoxDriverLogLevel.Default;
+        private string logPath = string.Empty;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="FirefoxDriverService"/> class.
@@ -153,6 +154,15 @@ protected override bool HasShutdown
             get { return false; }
         }
 
+        /// <summary>
+        /// Gets or sets the path to which service logging should be written.
+        /// </summary>
+        public string LogPath
+        {
+            get { return this.logPath; }
+            set { this.logPath = value; }
+        }
+
         /// <summary>
         /// Gets the command-line arguments for the driver service.
         /// </summary>
@@ -170,6 +180,12 @@ protected override string CommandLineArguments
                     argsBuilder.Append(string.Format(CultureInfo.InvariantCulture, " --websocket-port {0}", PortUtilities.FindFreePort()));
                 }
 
+                StringBuilder argsBuilder = new StringBuilder(base.CommandLineArguments);
+                if (!string.IsNullOrEmpty(this.logPath))
+                {
+                    argsBuilder.Append(string.Format(CultureInfo.InvariantCulture, " --log \"{0}\"", this.logPath));
+                }
+
                 if (this.browserCommunicationPort > 0)
                 {
                     argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --marionette-port {0}", this.browserCommunicationPort);

dotnet/test/firefox/FirefoxDriverServiceTests.cs

@@ -0,0 +1,63 @@
+using NUnit.Framework;
+using OpenQA.Selenium.Firefox;
+using System;
+using System.IO;
+
+namespace OpenQA.Selenium.Firefox
+{
+    [TestFixture]
+    public class FirefoxDriverServiceTests
+    {
+        private string tempFileName;
+
+        [SetUp]
+        public void Setup()
+        {
+            tempFileName = Path.GetTempFileName();
+            File.Delete(tempFileName);
+        }
+
+        [TearDown]
+        public void Teardown()
+        {
+            if (File.Exists(tempFileName))
+            {
+                File.Delete(tempFileName);
+            }
+        }
+
+        [Test]
+        public void CanSetLogPath()
+        {
+            var service = FirefoxDriverService.CreateDefaultService();
+            service.LogPath = tempFileName;
+
+            Assert.That(service.LogPath, Is.EqualTo(tempFileName), "LogPath should be set correctly");
+
+            string commandLineArgs = service.CommandLineArguments;
+            Assert.That(commandLineArgs, Contains.Substring($"--log \"{tempFileName}\""), 
+                "Command line arguments should contain the log path");
+        }
+
+        [Test]
+        public void LogFileIsCreatedWhenDriverStarts()
+        {
+            var service = FirefoxDriverService.CreateDefaultService();
+            service.LogPath = tempFileName;
+
+            service.Start();
+
+            try
+            {
+                Assert.That(File.Exists(tempFileName), Is.True, "Log file should be created when service starts");
+
+                string logContent = File.ReadAllText(tempFileName);
+                Assert.That(logContent, Is.Not.Empty, "Log file should contain content");
+            }
+            finally
+            {
+                service.Dispose();
+            }
+        }
+    }
+}

dotnet/test/firefox/FirefoxDriverTest.cs

@@ -360,6 +360,43 @@ public void ShouldInstallAndUninstallUnSignedDirAddon()
             Assert.That(driver.FindElements(By.Id("webextensions-selenium-example")).Count, Is.Zero);
         }
 
+        [Test]
+        public void ShouldBeAbleToLogToFile()
+        {
+            string tempFileName = Path.GetTempFileName();
+            try
+            {
+                File.Delete(tempFileName);
+                FirefoxOptions options = new FirefoxOptions();
+                FirefoxDriverService service = FirefoxDriverService.CreateDefaultService();
+                service.LogPath = tempFileName;
+
+                IWebDriver firefox = new FirefoxDriver(service, options);
+                firefox.Url = xhtmlTestPage;
+                Assert.That(firefox.Title, Is.EqualTo("XHTML Test Page"));
+
+                firefox.Quit();
+
+                Assert.That(File.Exists(tempFileName), Is.True, "Log file should exist");
+                string logContent = File.ReadAllText(tempFileName);
+                Assert.That(logContent, Is.Not.Empty, "Log file should not be empty");
+            }
+            finally
+            {
+                if (File.Exists(tempFileName))
+                {
+                    File.Delete(tempFileName);
+                }
+            }
+        }
+
+        [Test]
+        public void LogPathShouldBeNullByDefault()
+        {
+            FirefoxDriverService service = FirefoxDriverService.CreateDefaultService();
+            Assert.That(service.LogPath, Is.Empty);
+        }
+
         private string GetPath(string name)
         {
             string sCurrentDirectory = AppDomain.CurrentDomain.BaseDirectory;