Continued implementing the scaffolding:

- Added composition root
- Implemented XML resource for I18n

SafeExamBrowser.Core.UnitTests/I18n/TextTests.cs

@@ -13,21 +13,34 @@ using SafeExamBrowser.Core.I18n;
 namespace SafeExamBrowser.Core.UnitTests
 {
 	[TestClass]
-	public class StringsTests
+	public class TextTests
 	{
+		[TestMethod]
+		public void MustNeverBeNull()
+		{
+			Assert.IsNotNull(Text.Instance);
+		}
+
 		[TestMethod]
 		public void MustNeverReturnNull()
 		{
-			var text = Strings.Get((Key) (-1));
+			var text = Text.Instance.Get((Key) (-1));
 
 			Assert.IsNotNull(text);
 		}
 
+		[TestMethod]
+		[ExpectedException(typeof(ArgumentNullException))]
+		public void MustNotAllowBeingNull()
+		{
+			Text.Instance = null;
+		}
+
 		[TestMethod]
 		[ExpectedException(typeof(ArgumentNullException))]
 		public void MustNotAllowNullResource()
 		{
-			Strings.Initialize(null);
+			new Text(null);
 		}
 	}
 }

SafeExamBrowser.Core.UnitTests/SafeExamBrowser.Core.UnitTests.csproj

@@ -48,7 +48,7 @@
     <Reference Include="System.Core" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="I18n\StringsTests.cs" />
+    <Compile Include="I18n\TextTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>

SafeExamBrowser.Core/Contracts/ITextResource.cs

@@ -11,8 +11,8 @@ using SafeExamBrowser.Core.I18n;
 
 namespace SafeExamBrowser.Core.Contracts
 {
-	public interface IStringResource
+	public interface ITextResource
 	{
-		IDictionary<Key, string> LoadStrings();
+		IDictionary<Key, string> LoadText();
 	}
 }

SafeExamBrowser.Core/I18n/Key.cs

@@ -10,6 +10,7 @@ namespace SafeExamBrowser.Core.I18n
 {
 	public enum Key
 	{
+		MessageBox_FatalErrorTitle,
 		MessageBox_SingleInstance,
 		MessageBox_SingleInstanceTitle
 	}

SafeExamBrowser.Core/I18n/NullTextResource.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.Collections.Generic;
+using SafeExamBrowser.Core.Contracts;
+
+namespace SafeExamBrowser.Core.I18n
+{
+	class NullTextResource : ITextResource
+	{
+		public IDictionary<Key, string> LoadText()
+		{
+			return new Dictionary<Key, string>();
+		}
+	}
+}

SafeExamBrowser.Core/I18n/Text.cs

@@ -12,21 +12,42 @@ using SafeExamBrowser.Core.Contracts;
 
 namespace SafeExamBrowser.Core.I18n
 {
-	public static class Strings
+	public class Text
 	{
-		private static IDictionary<Key, string> cache = new Dictionary<Key, string>();
+		private static Text instance;
+		private static readonly object @lock = new object();
 
-		public static void Initialize(IStringResource resource)
+		private IDictionary<Key, string> cache = new Dictionary<Key, string>();
+
+		public Text(ITextResource resource)
 		{
 			if (resource == null)
 			{
 				throw new ArgumentNullException(nameof(resource));
 			}
 
-			cache = resource.LoadStrings();
+			cache = resource.LoadText();
 		}
 
-		public static string Get(Key key)
+		public static Text Instance
+		{
+			get
+			{
+				lock (@lock)
+				{
+					return instance ?? new Text(new NullTextResource());
+				}
+			}
+			set
+			{
+				lock (@lock)
+				{
+					instance = value ?? throw new ArgumentNullException(nameof(value));
+				}
+			}
+		}
+
+		public string Get(Key key)
 		{
 			return cache.ContainsKey(key) ? cache[key] : $"Could not find string for key '{key}'!";
 		}

SafeExamBrowser.Core/I18n/Text.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8" ?>
 <Text>
+  <MessageBox_FatalErrorTitle>Fatal Error</MessageBox_FatalErrorTitle>
   <MessageBox_SingleInstance>You can only run one instance of SEB at a time.</MessageBox_SingleInstance>
   <MessageBox_SingleInstanceTitle>Startup Not Allowed</MessageBox_SingleInstanceTitle>
 </Text>

SafeExamBrowser.Core/I18n/XmlTextResource.cs

@@ -0,0 +1,38 @@
+/*
+ * 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 System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+using System.Xml.Linq;
+using SafeExamBrowser.Core.Contracts;
+
+namespace SafeExamBrowser.Core.I18n
+{
+	public class XmlTextResource : ITextResource
+	{
+		public IDictionary<Key, string> LoadText()
+		{
+			var assembly = Assembly.GetAssembly(typeof(XmlTextResource)).Location;
+			var path = Path.GetDirectoryName(assembly) + $@"\{nameof(I18n)}\Text.xml";
+			var xml = XDocument.Load(path);
+			var text = new Dictionary<Key, string>();
+
+			foreach (var definition in xml.Root.Descendants())
+			{
+				if (Enum.TryParse(definition.Name.LocalName, out Key key))
+				{
+					text[key] = definition.Value;
+				}
+			}
+
+			return text;
+		}
+	}
+}

SafeExamBrowser.Core/SafeExamBrowser.Core.csproj

@@ -40,14 +40,18 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="Contracts\IStringResource.cs" />
+    <Compile Include="Contracts\ITextResource.cs" />
     <Compile Include="Contracts\ITaskbar.cs" />
     <Compile Include="I18n\Key.cs" />
-    <Compile Include="I18n\Strings.cs" />
+    <Compile Include="I18n\NullTextResource.cs" />
+    <Compile Include="I18n\Text.cs" />
+    <Compile Include="I18n\XmlTextResource.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
-    <Content Include="I18n\Text.xml" />
+    <Content Include="I18n\Text.xml">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
 </Project>

SafeExamBrowser/App.cs

@@ -10,7 +10,6 @@ using System;
 using System.Threading;
 using System.Windows;
 using SafeExamBrowser.Core.I18n;
-using SafeExamBrowser.UserInterface;
 
 namespace SafeExamBrowser
 {
@@ -21,22 +20,36 @@ namespace SafeExamBrowser
 		[STAThread]
 		public static void Main()
 		{
-			if (mutex.WaitOne(TimeSpan.Zero, true))
+			try
 			{
-				StartApplication();
+				var compositionRoot = new CompositionRoot();
+
+				compositionRoot.InitializeGlobalModules();
+				compositionRoot.BuildObjectGraph();
+
+				StartApplication(compositionRoot.Taskbar);
+			}
+			catch (Exception e)
+			{
+				MessageBox.Show(e.Message + "\n\n" + e.StackTrace, Text.Instance.Get(Key.MessageBox_FatalErrorTitle));
+			}
+		}
+
+		private static void StartApplication(Window taskbar)
+		{
+			if (NoInstanceRunning())
+			{
+				new App().Run(taskbar);
 			}
 			else
 			{
-				MessageBox.Show(Strings.Get(Key.MessageBox_SingleInstance), Strings.Get(Key.MessageBox_SingleInstanceTitle));
+				MessageBox.Show(Text.Instance.Get(Key.MessageBox_SingleInstance), Text.Instance.Get(Key.MessageBox_SingleInstanceTitle));
 			}
 		}
 
-		private static void StartApplication()
+		private static bool NoInstanceRunning()
 		{
-			var app = new App();
+			return mutex.WaitOne(TimeSpan.Zero, true);
-			var taskbar = new Taskbar();
-
-			app.Run(taskbar);
 		}
 	}
 }

SafeExamBrowser/CompositionRoot.cs

@@ -0,0 +1,29 @@
+/*
+ * 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.Windows;
+using SafeExamBrowser.Core.I18n;
+using SafeExamBrowser.UserInterface;
+
+namespace SafeExamBrowser
+{
+	class CompositionRoot
+	{
+		public Window Taskbar { get; private set; }
+
+		public void InitializeGlobalModules()
+		{
+			Text.Instance = new Text(new XmlTextResource());
+		}
+
+		public void BuildObjectGraph()
+		{
+			Taskbar = new Taskbar();
+		}
+	}
+}

SafeExamBrowser/SafeExamBrowser.csproj

@@ -51,6 +51,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="App.cs" />
+    <Compile Include="CompositionRoot.cs" />
     <Compile Include="Properties\AssemblyInfo.cs">
       <SubType>Code</SubType>
     </Compile>