[dotnet] Add examples for logging (#1541)

Add examples for dotnet logging

examples/dotnet/SeleniumDocs/Troubleshooting/LoggingTest.cs

@@ -0,0 +1,87 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using OpenQA.Selenium;
+using OpenQA.Selenium.Internal.Logging;
+using OpenQA.Selenium.Remote;
+using System;
+using System.Collections.Generic;
+
+namespace SeleniumDocs.Troubleshooting
+{
+    [TestClass]
+    public class LoggingTest
+    {
+        [TestMethod]
+        public void Logging()
+        {
+            Log.SetLevel(LogEventLevel.Trace);
+
+            // TODO: Replace it with coming FileLogHandler
+            var testLogHandler = new TestLogHandler();
+            Log.Handlers.Add(testLogHandler);
+
+            Log.SetLevel(typeof(RemoteWebDriver), LogEventLevel.Debug);
+            Log.SetLevel(typeof(SeleniumManager), LogEventLevel.Info);
+
+            Warn("this is a warning");
+            Info("this is useful information");
+            Debug("this is detailed debug information");
+
+            Assert.IsTrue(testLogHandler.Messages.Contains("this is a warning"));
+            Assert.IsTrue(testLogHandler.Messages.Contains("this is useful information"));
+            Assert.IsTrue(testLogHandler.Messages.Contains("this is detailed debug information"));
+        }
+
+        [TestCleanup]
+        public void TestCleanup()
+        {
+            // reset log to default
+            Log.SetLevel(LogEventLevel.Info)
+                .Handlers.Clear()
+                .Handlers.Add(new ConsoleLogHandler());
+        }
+
+        // logging is only for internal usage
+        // hacking it via reflection
+
+        private void Debug(string message)
+        {
+            LogMessage("Debug", message);
+        }
+
+        private void Warn(string message)
+        {
+            LogMessage("Warn", message);
+        }
+
+        private void Info(string message)
+        {
+            LogMessage("Info", message);
+        }
+
+        private void LogMessage(string methodName, string message)
+        {
+            var getLoggerMethod = typeof(Log).GetMethod("GetLogger", System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic, new Type[] { typeof(Type) });
+
+            var logger = getLoggerMethod.Invoke(null, new object[] { typeof(LoggingTest) });
+
+            var emitMethod = logger.GetType().GetMethod(methodName);
+
+            emitMethod.Invoke(logger, new object[] { message });
+        }
+
+        class TestLogHandler : ILogHandler
+        {
+            public ILogHandler Clone()
+            {
+                return this;
+            }
+
+            public void Handle(LogEvent logEvent)
+            {
+                Messages.Add(logEvent.Message);
+            }
+
+            public List<string> Messages { get; } = new List<string>();
+        }
+    }
+}