diff --git a/SafeExamBrowser.Contracts/Logging/ILogger.cs b/SafeExamBrowser.Contracts/Logging/ILogger.cs
index 8b4979ce..352f5a2f 100644
--- a/SafeExamBrowser.Contracts/Logging/ILogger.cs
+++ b/SafeExamBrowser.Contracts/Logging/ILogger.cs
@@ -16,37 +16,44 @@ namespace SafeExamBrowser.Contracts.Logging
 		/// <summary>
 		/// Logs the given message with severity <b>INFO</b>.
 		/// </summary>
+		/// <exception cref="ArgumentNullException" />
 		void Info(string message);
 
 		/// <summary>
 		/// Logs the given message with severity <b>WARNING</b>.
 		/// </summary>
+		/// <exception cref="ArgumentNullException" />
 		void Warn(string message);
 
 		/// <summary>
 		/// Logs the given message with severity <b>ERROR</b>.
 		/// </summary>
+		/// <exception cref="ArgumentNullException" />
 		void Error(string message);
 
 		/// <summary>
 		/// Logs the given message with severity <b>ERROR</b> and includes information about
 		/// the specified exception (i.e. type, message and stacktrace).
 		/// </summary>
+		/// <exception cref="ArgumentNullException" />
 		void Error(string message, Exception exception);
 
 		/// <summary>
 		/// Logs the given message as raw text.
 		/// </summary>
+		/// <exception cref="ArgumentNullException" />
 		void Log(string message);
 
 		/// <summary>
 		/// Appends the given content to the log.
 		/// </summary>
+		/// <exception cref="ArgumentNullException" />
 		void Log(ILogContent content);
 
 		/// <summary>
 		/// Suscribes an observer to the application log.
 		/// </summary>
+		/// <exception cref="ArgumentNullException" />
 		void Subscribe(ILogObserver observer);
 
 		/// <summary>
diff --git a/SafeExamBrowser.Core.UnitTests/Logging/DefaultLogFormatterTests.cs b/SafeExamBrowser.Core.UnitTests/Logging/DefaultLogFormatterTests.cs
new file mode 100644
index 00000000..1610b5b2
--- /dev/null
+++ b/SafeExamBrowser.Core.UnitTests/Logging/DefaultLogFormatterTests.cs
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2017 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Core.Logging;
+
+namespace SafeExamBrowser.Core.UnitTests.Logging
+{
+	[TestClass]
+	public class DefaultLogFormatterTests
+	{
+		[TestMethod]
+		[ExpectedException(typeof(NotImplementedException))]
+		public void MustReportNotYetImplementedLogContent()
+		{
+			var sut = new DefaultLogFormatter();
+
+			sut.Format(new NewLogContentType());
+		}
+
+		[TestMethod]
+		public void MustReturnRawTextForLogMessage()
+		{
+			var sut = new DefaultLogFormatter();
+			var entry = new LogText("Must return this text...");
+
+			var text = sut.Format(entry);
+
+			Assert.AreEqual(entry.Text, text);
+		}
+
+		[TestMethod]
+		public void MustCorrectlyFormatLogMessage()
+		{
+			var sut = new DefaultLogFormatter();
+			var date = new DateTime(2017, 10, 10, 15, 24, 38);
+			var threadInfo = new ThreadInfo(1234, "ABC");
+			var entry = new LogMessage(date, LogLevel.Warning, "Here's a warning message...", threadInfo);
+
+			var text = sut.Format(entry);
+
+			Assert.AreEqual($"2017-10-10 15:24:38.000 [1234: ABC] - WARNING: Here's a warning message...", text);
+		}
+	}
+}
diff --git a/SafeExamBrowser.Core.UnitTests/Logging/LoggerTests.cs b/SafeExamBrowser.Core.UnitTests/Logging/LoggerTests.cs
index 23f08876..4dcda524 100644
--- a/SafeExamBrowser.Core.UnitTests/Logging/LoggerTests.cs
+++ b/SafeExamBrowser.Core.UnitTests/Logging/LoggerTests.cs
@@ -67,6 +67,19 @@ namespace SafeExamBrowser.Core.UnitTests.Logging
 			}
 		}
 
+		[TestMethod]
+		public void MustNotAllowLoggingNull()
+		{
+			var sut = new Logger();
+
+			Assert.ThrowsException<ArgumentNullException>(() => sut.Info(null));
+			Assert.ThrowsException<ArgumentNullException>(() => sut.Warn(null));
+			Assert.ThrowsException<ArgumentNullException>(() => sut.Error(null));
+			Assert.ThrowsException<ArgumentNullException>(() => sut.Error(null, null));
+			Assert.ThrowsException<ArgumentNullException>(() => sut.Log((string) null));
+			Assert.ThrowsException<ArgumentNullException>(() => sut.Log((ILogContent) null));
+		}
+
 		[TestMethod]
 		[ExpectedException(typeof(ArgumentNullException))]
 		public void MustNotAllowNullObserver()
diff --git a/SafeExamBrowser.Core.UnitTests/Logging/ModuleLoggerTests.cs b/SafeExamBrowser.Core.UnitTests/Logging/ModuleLoggerTests.cs
new file mode 100644
index 00000000..44bcd05d
--- /dev/null
+++ b/SafeExamBrowser.Core.UnitTests/Logging/ModuleLoggerTests.cs
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2017 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Moq;
+using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Core.Logging;
+
+namespace SafeExamBrowser.Core.UnitTests.Logging
+{
+	[TestClass]
+	public class ModuleLoggerTests
+	{
+		[TestMethod]
+		public void MustCorrectlyForwardCalls()
+		{
+			var loggerMock = new Mock<ILogger>();
+			var logObserverMock = new Mock<ILogObserver>();
+			var logText = new LogText("Log text");
+			var sut = new ModuleLogger(loggerMock.Object, typeof(ModuleLoggerTests));
+
+			sut.Info("Info");
+			sut.Warn("Warning");
+			sut.Error("Error");
+			sut.Log("Raw text");
+			sut.Log(logText);
+			sut.Subscribe(logObserverMock.Object);
+			sut.Unsubscribe(logObserverMock.Object);
+			sut.GetLog();
+
+			loggerMock.Verify(l => l.Info($"[{nameof(ModuleLoggerTests)}] Info"), Times.Once);
+			loggerMock.Verify(l => l.Warn($"[{nameof(ModuleLoggerTests)}] Warning"), Times.Once);
+			loggerMock.Verify(l => l.Error($"[{nameof(ModuleLoggerTests)}] Error"), Times.Once);
+			loggerMock.Verify(l => l.Log("Raw text"), Times.Once);
+			loggerMock.Verify(l => l.Log(logText), Times.Once);
+			loggerMock.Verify(l => l.Subscribe(logObserverMock.Object), Times.Once);
+			loggerMock.Verify(l => l.Unsubscribe(logObserverMock.Object), Times.Once);
+			loggerMock.Verify(l => l.GetLog(), Times.Once);
+		}
+	}
+}
diff --git a/SafeExamBrowser.Core.UnitTests/Logging/NewLogContentType.cs b/SafeExamBrowser.Core.UnitTests/Logging/NewLogContentType.cs
new file mode 100644
index 00000000..c56912ca
--- /dev/null
+++ b/SafeExamBrowser.Core.UnitTests/Logging/NewLogContentType.cs
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2017 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using SafeExamBrowser.Contracts.Logging;
+
+namespace SafeExamBrowser.Core.UnitTests.Logging
+{
+	class NewLogContentType : ILogContent
+	{
+		public object Clone()
+		{
+			throw new NotImplementedException();
+		}
+	}
+}
diff --git a/SafeExamBrowser.Core.UnitTests/SafeExamBrowser.Core.UnitTests.csproj b/SafeExamBrowser.Core.UnitTests/SafeExamBrowser.Core.UnitTests.csproj
index f0ab8304..3f26e552 100644
--- a/SafeExamBrowser.Core.UnitTests/SafeExamBrowser.Core.UnitTests.csproj
+++ b/SafeExamBrowser.Core.UnitTests/SafeExamBrowser.Core.UnitTests.csproj
@@ -77,7 +77,10 @@
     <Compile Include="Behaviour\ShutdownControllerTests.cs" />
     <Compile Include="I18n\TextTests.cs" />
     <Compile Include="I18n\XmlTextResourceTests.cs" />
+    <Compile Include="Logging\DefaultLogFormatterTests.cs" />
     <Compile Include="Logging\LoggerTests.cs" />
+    <Compile Include="Logging\ModuleLoggerTests.cs" />
+    <Compile Include="Logging\NewLogContentType.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
diff --git a/SafeExamBrowser.Core/Logging/LogMessage.cs b/SafeExamBrowser.Core/Logging/LogMessage.cs
index a39d6cf4..e463c1c4 100644
--- a/SafeExamBrowser.Core/Logging/LogMessage.cs
+++ b/SafeExamBrowser.Core/Logging/LogMessage.cs
@@ -9,9 +9,9 @@
 using System;
 using SafeExamBrowser.Contracts.Logging;
 
-namespace SafeExamBrowser.Core.Entities
+namespace SafeExamBrowser.Core.Logging
 {
-	class LogMessage : ILogMessage
+	public class LogMessage : ILogMessage
 	{
 		public DateTime DateTime { get; private set; }
 		public LogLevel Severity { get; private set; }
diff --git a/SafeExamBrowser.Core/Logging/Logger.cs b/SafeExamBrowser.Core/Logging/Logger.cs
index 7e65fa76..25a8137b 100644
--- a/SafeExamBrowser.Core/Logging/Logger.cs
+++ b/SafeExamBrowser.Core/Logging/Logger.cs
@@ -12,7 +12,6 @@ using System.Linq;
 using System.Text;
 using System.Threading;
 using SafeExamBrowser.Contracts.Logging;
-using SafeExamBrowser.Core.Entities;
 
 namespace SafeExamBrowser.Core.Logging
 {
@@ -24,21 +23,46 @@ namespace SafeExamBrowser.Core.Logging
 
 		public void Info(string message)
 		{
+			if (message == null)
+			{
+				throw new ArgumentNullException(nameof(message));
+			}
+
 			Add(LogLevel.Info, message);
 		}
 
 		public void Warn(string message)
 		{
+			if (message == null)
+			{
+				throw new ArgumentNullException(nameof(message));
+			}
+
 			Add(LogLevel.Warning, message);
 		}
 
 		public void Error(string message)
 		{
+			if (message == null)
+			{
+				throw new ArgumentNullException(nameof(message));
+			}
+
 			Add(LogLevel.Error, message);
 		}
 
 		public void Error(string message, Exception exception)
 		{
+			if (message == null)
+			{
+				throw new ArgumentNullException(nameof(message));
+			}
+
+			if (exception == null)
+			{
+				throw new ArgumentNullException(nameof(exception));
+			}
+
 			var details = new StringBuilder();
 
 			details.AppendLine();
diff --git a/SafeExamBrowser.Core/Logging/ThreadInfo.cs b/SafeExamBrowser.Core/Logging/ThreadInfo.cs
index d7b7a666..43b6d088 100644
--- a/SafeExamBrowser.Core/Logging/ThreadInfo.cs
+++ b/SafeExamBrowser.Core/Logging/ThreadInfo.cs
@@ -11,7 +11,7 @@ using SafeExamBrowser.Contracts.Logging;
 
 namespace SafeExamBrowser.Core.Logging
 {
-	class ThreadInfo : IThreadInfo
+	public class ThreadInfo : IThreadInfo
 	{
 		public int Id { get; private set; }
 		public string Name { get; private set; }