SEBWIN-219: Extracted creation of proxy and host objects from base implementations and started implementing unit tests for hosts.

SafeExamBrowser.Client/Communication/ClientHost.cs

@@ -24,7 +24,7 @@ namespace SafeExamBrowser.Client.Communication
 
 		public event CommunicationEventHandler Shutdown;
 
-		public ClientHost(string address, ILogger logger, int processId) : base(address, logger)
+		public ClientHost(string address, IHostObjectFactory factory, ILogger logger, int processId) : base(address, factory, logger)
 		{
 			this.processId = processId;
 		}

SafeExamBrowser.Client/CompositionRoot.cs

@@ -26,6 +26,7 @@ using SafeExamBrowser.Contracts.UserInterface;
 using SafeExamBrowser.Contracts.UserInterface.MessageBox;
 using SafeExamBrowser.Contracts.WindowsApi;
 using SafeExamBrowser.Core.Behaviour.OperationModel;
+using SafeExamBrowser.Core.Communication.Hosts;
 using SafeExamBrowser.Core.Communication.Proxies;
 using SafeExamBrowser.Core.I18n;
 using SafeExamBrowser.Core.Logging;
@@ -159,7 +160,8 @@ namespace SafeExamBrowser.Client
 		private IOperation BuildCommunicationHostOperation()
 		{
 			var processId = Process.GetCurrentProcess().Id;
-			var host = new ClientHost(configuration.RuntimeInfo.ClientAddress, new ModuleLogger(logger, typeof(ClientHost)), processId);
+			var factory = new HostObjectFactory();
+			var host = new ClientHost(configuration.RuntimeInfo.ClientAddress, factory, new ModuleLogger(logger, typeof(ClientHost)), processId);
 			var operation = new CommunicationOperation(host, logger);
 
 			clientHost = host;

SafeExamBrowser.Contracts/Communication/Hosts/IHostObject.cs

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2018 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.ServiceModel;
+
+namespace SafeExamBrowser.Contracts.Communication.Hosts
+{
+	/// <summary>
+	/// The host object to be used in communication hosts.
+	/// </summary>
+	public interface IHostObject : ICommunicationObject
+	{
+	}
+}

SafeExamBrowser.Contracts/Communication/Hosts/IHostObjectFactory.cs

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2018 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/.
+ */
+
+namespace SafeExamBrowser.Contracts.Communication.Hosts
+{
+	/// <summary>
+	/// A factory to create host objects for communication hosts.
+	/// </summary>
+	public interface IHostObjectFactory
+	{
+		/// <summary>
+		/// Utilizes the given communication object to create a host object (see <see cref="IHostObject"/>) for the specified endpoint address.
+		/// </summary>
+		IHostObject CreateObject(string address, ICommunication communicationObject);
+	}
+}

SafeExamBrowser.Contracts/Communication/Proxies/IProxyObject.cs

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2018 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.ServiceModel;
+
+namespace SafeExamBrowser.Contracts.Communication.Proxies
+{
+	/// <summary>
+	/// The communication object to be used in an <see cref="ICommunicationProxy"/>.
+	/// </summary>
+	public interface IProxyObject : ICommunication, ICommunicationObject
+	{
+	}
+}

SafeExamBrowser.Contracts/Communication/Proxies/IProxyObjectFactory.cs

@@ -9,13 +9,13 @@
 namespace SafeExamBrowser.Contracts.Communication.Proxies
 {
 	/// <summary>
-	/// A factory to create communication objects for proxies.
+	/// A factory to create proxy objects for communication proxies.
 	/// </summary>
 	public interface IProxyObjectFactory
 	{
 		/// <summary>
-		/// Creates a communication object (see <see cref="ICommunication"/>) for the specified endpoint address.
+		/// Creates a proxy object (see <see cref="IProxyObject"/>) for the specified endpoint address.
 		/// </summary>
-		ICommunication CreateObject(string address);
+		IProxyObject CreateObject(string address);
 	}
 }

SafeExamBrowser.Contracts/SafeExamBrowser.Contracts.csproj

@@ -58,10 +58,13 @@
     <Compile Include="Behaviour\OperationModel\IOperationSequence.cs" />
     <Compile Include="Behaviour\OperationModel\OperationResult.cs" />
     <Compile Include="Communication\Hosts\IClientHost.cs" />
+    <Compile Include="Communication\Hosts\IHostObject.cs" />
+    <Compile Include="Communication\Hosts\IHostObjectFactory.cs" />
     <Compile Include="Communication\ICommunication.cs" />
     <Compile Include="Communication\Proxies\IClientProxy.cs" />
     <Compile Include="Communication\ICommunicationHost.cs" />
     <Compile Include="Communication\ICommunicationProxy.cs" />
+    <Compile Include="Communication\Proxies\IProxyObject.cs" />
     <Compile Include="Communication\Proxies\IProxyObjectFactory.cs" />
     <Compile Include="Communication\Proxies\IProxyFactory.cs" />
     <Compile Include="Communication\Hosts\IRuntimeHost.cs" />

SafeExamBrowser.Core.UnitTests/Communication/Hosts/BaseHostImpl.cs

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2018 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.Communication.Data;
+using SafeExamBrowser.Contracts.Communication.Hosts;
+using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Core.Communication.Hosts;
+
+namespace SafeExamBrowser.Core.UnitTests.Communication.Hosts
+{
+	internal class BaseHostImpl : BaseHost
+	{
+		public Func<Guid?, bool> OnConnectStub { get; set; }
+		public Action OnDisconnectStub { get; set; }
+		public Func<Message, Response> OnReceiveStub { get; set; }
+		public Func<SimpleMessagePurport, Response> OnReceiveSimpleMessageStub { get; set; }
+
+		public BaseHostImpl(string address, IHostObjectFactory factory, ILogger logger) : base(address, factory, logger)
+		{
+		}
+
+		public Guid? GetCommunicationToken()
+		{
+			return CommunicationToken;
+		}
+
+		protected override bool OnConnect(Guid? token)
+		{
+			return OnConnectStub?.Invoke(token) == true;
+		}
+
+		protected override void OnDisconnect()
+		{
+			OnDisconnectStub?.Invoke();
+		}
+
+		protected override Response OnReceive(Message message)
+		{
+			return OnReceiveStub?.Invoke(message);
+		}
+
+		protected override Response OnReceive(SimpleMessagePurport message)
+		{
+			return OnReceiveSimpleMessageStub?.Invoke(message);
+		}
+	}
+}

SafeExamBrowser.Core.UnitTests/Communication/Hosts/BaseHostTests.cs

@@ -0,0 +1,227 @@
+/*
+ * Copyright (c) 2018 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.ServiceModel;
+using System.Threading;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Moq;
+using SafeExamBrowser.Contracts.Communication;
+using SafeExamBrowser.Contracts.Communication.Data;
+using SafeExamBrowser.Contracts.Communication.Hosts;
+using SafeExamBrowser.Contracts.Logging;
+
+namespace SafeExamBrowser.Core.UnitTests.Communication.Hosts
+{
+	[TestClass]
+	public class BaseHostTests
+	{
+		private Mock<IHostObject> hostObject;
+		private Mock<IHostObjectFactory> hostObjectFactory;
+		private Mock<ILogger> logger;
+		private BaseHostImpl sut;
+
+		[TestInitialize]
+		public void Initialize()
+		{
+			hostObject = new Mock<IHostObject>();
+			hostObjectFactory = new Mock<IHostObjectFactory>();
+			logger = new Mock<ILogger>();
+
+			hostObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>(), It.IsAny<ICommunication>())).Returns(hostObject.Object);
+
+			sut = new BaseHostImpl("net.pipe://some/address/here", hostObjectFactory.Object, logger.Object);
+		}
+
+		[TestMethod]
+		public void MustCorrectlyStartHost()
+		{
+			var threadId = Thread.CurrentThread.ManagedThreadId;
+
+			hostObject.Setup(h => h.Open()).Callback(() => threadId = Thread.CurrentThread.ManagedThreadId);
+
+			sut.Start();
+
+			hostObjectFactory.Verify(f => f.CreateObject(It.IsAny<string>(), sut), Times.Once);
+
+			Assert.AreNotEqual(Thread.CurrentThread.ManagedThreadId, threadId);
+		}
+
+		[TestMethod]
+		[ExpectedException(typeof(CommunicationException))]
+		public void MustCorrectlyHandleStartupException()
+		{
+			hostObject.Setup(h => h.Open()).Throws<Exception>();
+
+			sut.Start();
+		}
+
+		[TestMethod]
+		public void MustCorrectlyStopHost()
+		{
+			sut.Start();
+			sut.Stop();
+
+			hostObject.Verify(h => h.Close(), Times.Once);
+		}
+
+		[TestMethod]
+		[ExpectedException(typeof(CommunicationException))]
+		public void MustCorrectlyHandleShutdownException()
+		{
+			hostObject.Setup(h => h.Close()).Throws<Exception>();
+
+			sut.Start();
+			sut.Stop();
+		}
+
+		[TestMethod]
+		public void MustNotFailToStopIfNotRunning()
+		{
+			sut.Stop();
+			sut.Stop();
+			sut.Stop();
+		}
+
+		[TestMethod]
+		public void MustNotFailToEvaluateIsRunningIfNotRunning()
+		{
+			var running = sut.IsRunning;
+
+			Assert.IsFalse(running);
+		}
+
+		[TestMethod]
+		public void MustCorrectlyIndicateWhetherHostIsRunning()
+		{
+			hostObject.SetupGet(h => h.State).Returns(CommunicationState.Faulted);
+
+			sut.Start();
+
+			Assert.IsFalse(sut.IsRunning);
+
+			hostObject.SetupGet(h => h.State).Returns(CommunicationState.Opened);
+
+			Assert.IsTrue(sut.IsRunning);
+		}
+
+		[TestMethod]
+		public void MustCorrectlyHandleConnectionRequest()
+		{
+			var token = Guid.NewGuid();
+			var receivedToken = default(Guid?);
+
+			sut.OnConnectStub = (t) =>
+			{
+				receivedToken = t;
+
+				return true;
+			};
+
+			var response = sut.Connect(token);
+
+			Assert.IsTrue(response.ConnectionEstablished);
+			Assert.AreEqual(token, receivedToken);
+			Assert.AreEqual(sut.GetCommunicationToken(), response.CommunicationToken);
+		}
+
+		[TestMethod]
+		public void MustCorrectlyHandleDeniedConnectionRequest()
+		{
+			var token = Guid.NewGuid();
+			var receivedToken = default(Guid?);
+
+			sut.OnConnectStub = (t) =>
+			{
+				receivedToken = t;
+
+				return false;
+			};
+
+			var response = sut.Connect(token);
+
+			Assert.IsFalse(response.ConnectionEstablished);
+			Assert.AreEqual(token, receivedToken);
+			Assert.IsNull(sut.GetCommunicationToken());
+			Assert.IsNull(response.CommunicationToken);
+		}
+
+		[TestMethod]
+		public void MustCorrectlyHandleDisconnectionRequest()
+		{
+			var message = new DisconnectionMessage();
+			var disconnected = false;
+
+			sut.OnConnectStub = (t) => { return true; };
+			sut.OnDisconnectStub = () => disconnected = true;
+			sut.Connect();
+
+			message.CommunicationToken = sut.GetCommunicationToken().Value;
+
+			var response = sut.Disconnect(message);
+
+			Assert.IsTrue(disconnected);
+			Assert.IsTrue(response.ConnectionTerminated);
+			Assert.IsNull(sut.GetCommunicationToken());
+		}
+
+		[TestMethod]
+		public void MustCorrectlyHandleUnauthorizedDisconnectionRequest()
+		{
+			var disconnected = false;
+
+			sut.OnConnectStub = (t) => { return true; };
+			sut.OnDisconnectStub = () => disconnected = true;
+			sut.Connect();
+
+			var response = sut.Disconnect(new DisconnectionMessage());
+
+			Assert.IsFalse(disconnected);
+			Assert.IsFalse(response.ConnectionTerminated);
+			Assert.IsNotNull(sut.GetCommunicationToken());
+		}
+
+		[TestMethod]
+		public void MustCorrectlyHandleUnauthorizedTransmission()
+		{
+			var received = false;
+			var simpleReceived = false;
+
+			sut.OnReceiveStub = (m) => { received = true; return null; };
+			sut.OnReceiveSimpleMessageStub = (m) => { simpleReceived = true; return null; };
+
+			var response = sut.Send(new DisconnectionMessage());
+
+			Assert.IsFalse(received);
+			Assert.IsFalse(simpleReceived);
+			Assert.IsInstanceOfType(response, typeof(SimpleResponse));
+			Assert.AreEqual(SimpleResponsePurport.Unauthorized, (response as SimpleResponse)?.Purport);
+		}
+
+		[TestMethod]
+		public void MustCorrectlyHandlePingMessage()
+		{
+			// TODO
+			Assert.Fail();
+		}
+
+		[TestMethod]
+		public void MustCorrectlyReceiveSimpleMessage()
+		{
+			// TODO
+			Assert.Fail();
+		}
+
+		[TestMethod]
+		public void MustCorrectlyReceiveMessage()
+		{
+			// TODO
+			Assert.Fail();
+		}
+	}
+}

SafeExamBrowser.Core.UnitTests/Communication/Proxies/BaseProxyTests.cs

@@ -10,7 +10,6 @@ using System;
 using System.ServiceModel;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
-using SafeExamBrowser.Contracts.Communication;
 using SafeExamBrowser.Contracts.Communication.Data;
 using SafeExamBrowser.Contracts.Communication.Proxies;
 using SafeExamBrowser.Contracts.Logging;
@@ -36,7 +35,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		[TestMethod]
 		public void MustConnectCorrectly()
 		{
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var response = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -58,7 +57,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		[TestMethod]
 		public void MustDisconnectCorrectly()
 		{
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var connectionResponse = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -71,7 +70,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(connectionResponse);
 			proxy.Setup(p => p.Disconnect(It.IsAny<DisconnectionMessage>())).Returns(disconnectionResponse);
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			var token = Guid.NewGuid();
@@ -87,7 +86,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		[TestMethod]
 		public void MustHandleConnectionRefusalCorrectly()
 		{
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var response = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -117,7 +116,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		[ExpectedException(typeof(CommunicationException))]
 		public void MustFailToDisconnectIfChannelNotOpen()
 		{
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var response = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -125,7 +124,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 			};
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(response);
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Faulted);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Faulted);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			var token = Guid.NewGuid();
@@ -145,7 +144,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		[ExpectedException(typeof(CommunicationException))]
 		public void MustFailToSendIfChannelNotOpen()
 		{
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var response = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -153,7 +152,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 			};
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(response);
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Faulted);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Faulted);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			var token = Guid.NewGuid();
@@ -172,7 +171,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		[TestMethod]
 		public void MustSendCorrectly()
 		{
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var connectionResponse = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -183,7 +182,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(connectionResponse);
 			proxy.Setup(p => p.Send(message)).Returns(response.Object);
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			var token = Guid.NewGuid();
@@ -197,7 +196,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		[TestMethod]
 		public void MustSendSimpleMessageCorrectly()
 		{
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var connectionResponse = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -208,7 +207,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(connectionResponse);
 			proxy.Setup(p => p.Send(It.IsAny<Message>())).Returns(response.Object);
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			var token = Guid.NewGuid();
@@ -255,7 +254,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		[TestMethod]
 		public void TestConnectionMustPingHost()
 		{
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var connectionResponse = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -264,7 +263,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(connectionResponse);
 			proxy.Setup(p => p.Send(It.Is<SimpleMessage>(m => m.Purport == SimpleMessagePurport.Ping))).Returns(new SimpleResponse(SimpleResponsePurport.Acknowledged));
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			var token = Guid.NewGuid();
@@ -279,7 +278,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		public void TestConnectionMustInvokeConnectionLostEvent()
 		{
 			var lost = false;
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var connectionResponse = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -290,7 +289,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(connectionResponse);
 			proxy.Setup(p => p.Send(It.Is<SimpleMessage>(m => m.Purport == SimpleMessagePurport.Ping))).Returns(new SimpleResponse(SimpleResponsePurport.UnknownMessage));
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			var token = Guid.NewGuid();
@@ -305,7 +304,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 		public void TestConnectionMustNotFail()
 		{
 			var lost = false;
-			var proxy = new Mock<ICommunication>();
+			var proxy = new Mock<IProxyObject>();
 			var connectionResponse = new ConnectionResponse
 			{
 				CommunicationToken = Guid.NewGuid(),
@@ -316,7 +315,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(connectionResponse);
 			proxy.Setup(p => p.Send(It.IsAny<Message>())).Throws<Exception>();
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			var token = Guid.NewGuid();

SafeExamBrowser.Core.UnitTests/Communication/Proxies/ClientProxyTests.cs

@@ -23,7 +23,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 	{
 		private Mock<ILogger> logger;
 		private Mock<IProxyObjectFactory> proxyObjectFactory;
-		private Mock<ICommunication> proxy;
+		private Mock<IProxyObject> proxy;
 		private ClientProxy sut;
 
 		[TestInitialize]
@@ -37,10 +37,10 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			logger = new Mock<ILogger>();
 			proxyObjectFactory = new Mock<IProxyObjectFactory>();
-			proxy = new Mock<ICommunication>();
+			proxy = new Mock<IProxyObject>();
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(response);
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			sut = new ClientProxy("net.pipe://random/address/here", proxyObjectFactory.Object, logger.Object);

SafeExamBrowser.Core.UnitTests/Communication/Proxies/RuntimeProxyTests.cs

@@ -24,7 +24,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 	{
 		private Mock<ILogger> logger;
 		private Mock<IProxyObjectFactory> proxyObjectFactory;
-		private Mock<ICommunication> proxy;
+		private Mock<IProxyObject> proxy;
 		private RuntimeProxy sut;
 
 		[TestInitialize]
@@ -38,10 +38,10 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			logger = new Mock<ILogger>();
 			proxyObjectFactory = new Mock<IProxyObjectFactory>();
-			proxy = new Mock<ICommunication>();
+			proxy = new Mock<IProxyObject>();
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(response);
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			sut = new RuntimeProxy("net.pipe://random/address/here", proxyObjectFactory.Object, logger.Object);

SafeExamBrowser.Core.UnitTests/Communication/Proxies/ServiceProxyTests.cs

@@ -23,7 +23,7 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 	{
 		private Mock<ILogger> logger;
 		private Mock<IProxyObjectFactory> proxyObjectFactory;
-		private Mock<ICommunication> proxy;
+		private Mock<IProxyObject> proxy;
 		private ServiceProxy sut;
 
 		[TestInitialize]
@@ -37,10 +37,10 @@ namespace SafeExamBrowser.Core.UnitTests.Communication.Proxies
 
 			logger = new Mock<ILogger>();
 			proxyObjectFactory = new Mock<IProxyObjectFactory>();
-			proxy = new Mock<ICommunication>();
+			proxy = new Mock<IProxyObject>();
 
 			proxy.Setup(p => p.Connect(It.IsAny<Guid>())).Returns(response);
-			proxy.As<ICommunicationObject>().Setup(o => o.State).Returns(CommunicationState.Opened);
+			proxy.Setup(o => o.State).Returns(CommunicationState.Opened);
 			proxyObjectFactory.Setup(f => f.CreateObject(It.IsAny<string>())).Returns(proxy.Object);
 
 			sut = new ServiceProxy("net.pipe://random/address/here", proxyObjectFactory.Object, logger.Object);

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

@@ -84,6 +84,8 @@
     <Compile Include="Behaviour\OperationModel\I18nOperationTests.cs" />
     <Compile Include="Behaviour\OperationModel\DelegateOperationTests.cs" />
     <Compile Include="Behaviour\OperationModel\OperationSequenceTests.cs" />
+    <Compile Include="Communication\Hosts\BaseHostImpl.cs" />
+    <Compile Include="Communication\Hosts\BaseHostTests.cs" />
     <Compile Include="Communication\Proxies\BaseProxyImpl.cs" />
     <Compile Include="Communication\Proxies\BaseProxyTests.cs" />
     <Compile Include="Communication\Proxies\ClientProxyTests.cs" />

SafeExamBrowser.Core/Communication/Hosts/BaseHost.cs

@@ -11,6 +11,7 @@ using System.ServiceModel;
 using System.Threading;
 using SafeExamBrowser.Contracts.Communication;
 using SafeExamBrowser.Contracts.Communication.Data;
+using SafeExamBrowser.Contracts.Communication.Hosts;
 using SafeExamBrowser.Contracts.Logging;
 
 namespace SafeExamBrowser.Core.Communication.Hosts
@@ -25,7 +26,8 @@ namespace SafeExamBrowser.Core.Communication.Hosts
 		private readonly object @lock = new object();
 
 		private string address;
-		private ServiceHost host;
+		private IHostObject host;
+		private IHostObjectFactory factory;
 		private Thread hostThread;
 
 		protected Guid? CommunicationToken { get; private set; }
@@ -42,9 +44,10 @@ namespace SafeExamBrowser.Core.Communication.Hosts
 			}
 		}
 
-		public BaseHost(string address, ILogger logger)
+		public BaseHost(string address, IHostObjectFactory factory, ILogger logger)
 		{
 			this.address = address;
+			this.factory = factory;
 			this.Logger = logger;
 		}
 
@@ -153,7 +156,7 @@ namespace SafeExamBrowser.Core.Communication.Hosts
 				{
 					Logger.Debug($"Terminated communication host for endpoint '{address}'.");
 				}
-				else
+				else if (exception != null)
 				{
 					throw new CommunicationException($"Failed to terminate communication host for endpoint '{address}'!", exception);
 				}
@@ -171,16 +174,15 @@ namespace SafeExamBrowser.Core.Communication.Hosts
 
 			try
 			{
-				host = new ServiceHost(this);
+				host = factory.CreateObject(address, this);
-				host.AddServiceEndpoint(typeof(ICommunication), new NetNamedPipeBinding(NetNamedPipeSecurityMode.Transport), address);
+
 				host.Closed += Host_Closed;
 				host.Closing += Host_Closing;
 				host.Faulted += Host_Faulted;
 				host.Opened += Host_Opened;
 				host.Opening += Host_Opening;
-				host.UnknownMessageReceived += Host_UnknownMessageReceived;
-				host.Open();
 
+				host.Open();
 				Logger.Debug($"Successfully started communication host for endpoint '{address}'.");
 
 				startedEvent.Set();
@@ -200,7 +202,7 @@ namespace SafeExamBrowser.Core.Communication.Hosts
 			try
 			{
 				host?.Close();
-				success = hostThread.Join(TWO_SECONDS);
+				success = hostThread?.Join(TWO_SECONDS) == true;
 			}
 			catch (Exception e)
 			{
@@ -236,11 +238,6 @@ namespace SafeExamBrowser.Core.Communication.Hosts
 			Logger.Debug("Communication host is opening...");
 		}
 
-		private void Host_UnknownMessageReceived(object sender, UnknownMessageReceivedEventArgs e)
-		{
-			Logger.Warn($"Communication host has received an unknown message: {e?.Message}.");
-		}
-
 		private string ToString(Message message)
 		{
 			return message != null ? message.ToString() : "<null>";

SafeExamBrowser.Core/Communication/Hosts/HostObjectFactory.cs

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2018 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.ServiceModel;
+using SafeExamBrowser.Contracts.Communication;
+using SafeExamBrowser.Contracts.Communication.Hosts;
+
+namespace SafeExamBrowser.Core.Communication.Hosts
+{
+	/// <summary>
+	/// Default implementation of the <see cref="IHostObjectFactory"/> utilizing WCF (<see cref="ServiceHost"/>).
+	/// </summary>
+	public class HostObjectFactory : IHostObjectFactory
+	{
+		public IHostObject CreateObject(string address, ICommunication communicationObject)
+		{
+			var host = new Host(communicationObject);
+
+			host.AddServiceEndpoint(typeof(ICommunication), new NetNamedPipeBinding(NetNamedPipeSecurityMode.Transport), address);
+
+			return host;
+		}
+
+		private class Host : ServiceHost, IHostObject
+		{
+			internal Host(object singletonInstance, params Uri[] baseAddresses) : base(singletonInstance, baseAddresses)
+			{
+			}
+		}
+	}
+}

SafeExamBrowser.Core/Communication/Proxies/BaseProxy.cs

@@ -25,7 +25,7 @@ namespace SafeExamBrowser.Core.Communication.Proxies
 		private static readonly object @lock = new object();
 
 		private string address;
-		private ICommunication proxy;
+		private IProxyObject proxy;
 		private IProxyObjectFactory factory;
 		private Guid? communicationToken;
 		private Timer timer;
@@ -43,19 +43,10 @@ namespace SafeExamBrowser.Core.Communication.Proxies
 
 		public virtual bool Connect(Guid? token = null, bool autoPing = true)
 		{
-			proxy = factory.CreateObject(address);
-
-			if (proxy is ICommunicationObject communicationObject)
-			{
-				communicationObject.Closed += BaseProxy_Closed;
-				communicationObject.Closing += BaseProxy_Closing;
-				communicationObject.Faulted += BaseProxy_Faulted;
-				communicationObject.Opened += BaseProxy_Opened;
-				communicationObject.Opening += BaseProxy_Opening;
-			}
-
 			Logger.Debug($"Trying to connect to endpoint '{address}'{(token.HasValue ? $" with authentication token '{token}'" : string.Empty)}...");
 
+			InitializeProxyObject();
+
 			var response = proxy.Connect(token);
 
 			communicationToken = response.CommunicationToken;
@@ -160,13 +151,24 @@ namespace SafeExamBrowser.Core.Communication.Proxies
 		}
 
 		/// <summary>
-		/// etrieves the string representation of the given <see cref="Response"/>, or indicates that a response is <c>null</c>.
+		/// Retrieves the string representation of the given <see cref="Response"/>, or indicates that a response is <c>null</c>.
 		/// </summary>
 		protected string ToString(Response response)
 		{
 			return response != null ? response.ToString() : "<null>";
 		}
 
+		private void InitializeProxyObject()
+		{
+			proxy = factory.CreateObject(address);
+
+			proxy.Closed += BaseProxy_Closed;
+			proxy.Closing += BaseProxy_Closing;
+			proxy.Faulted += BaseProxy_Faulted;
+			proxy.Opened += BaseProxy_Opened;
+			proxy.Opening += BaseProxy_Opening;
+		}
+
 		private void BaseProxy_Closed(object sender, EventArgs e)
 		{
 			Logger.Debug("Communication channel has been closed.");
@@ -199,7 +201,7 @@ namespace SafeExamBrowser.Core.Communication.Proxies
 				throw new InvalidOperationException($"Cannot perform '{operationName}' before being connected to endpoint!");
 			}
 
-			if (proxy == null || (proxy as ICommunicationObject)?.State != CommunicationState.Opened)
+			if (proxy == null || proxy.State != CommunicationState.Opened)
 			{
 				throw new CommunicationException($"Tried to perform {operationName}, but channel was {GetChannelState()}!");
 			}
@@ -207,7 +209,7 @@ namespace SafeExamBrowser.Core.Communication.Proxies
 
 		private string GetChannelState()
 		{
-			return proxy == null ? "null" : $"in state '{(proxy as ICommunicationObject)?.State}'";
+			return proxy == null ? "null" : $"in state '{proxy.State}'";
 		}
 
 		private void StartAutoPing()

SafeExamBrowser.Core/Communication/Proxies/ProxyObjectFactory.cs

@@ -7,7 +7,6 @@
  */
 
 using System.ServiceModel;
-using SafeExamBrowser.Contracts.Communication;
 using SafeExamBrowser.Contracts.Communication.Proxies;
 
 namespace SafeExamBrowser.Core.Communication.Proxies
@@ -17,10 +16,10 @@ namespace SafeExamBrowser.Core.Communication.Proxies
 	/// </summary>
 	public class ProxyObjectFactory : IProxyObjectFactory
 	{
-		public ICommunication CreateObject(string address)
+		public IProxyObject CreateObject(string address)
 		{
 			var endpoint = new EndpointAddress(address);
-			var channel = ChannelFactory<ICommunication>.CreateChannel(new NetNamedPipeBinding(NetNamedPipeSecurityMode.Transport), endpoint);
+			var channel = ChannelFactory<IProxyObject>.CreateChannel(new NetNamedPipeBinding(NetNamedPipeSecurityMode.Transport), endpoint);
 
 			return channel;
 		}

SafeExamBrowser.Core/SafeExamBrowser.Core.csproj

@@ -60,6 +60,7 @@
     <Compile Include="Behaviour\OperationModel\I18nOperation.cs" />
     <Compile Include="Behaviour\OperationModel\DelegateOperation.cs" />
     <Compile Include="Behaviour\OperationModel\OperationSequence.cs" />
+    <Compile Include="Communication\Hosts\HostObjectFactory.cs" />
     <Compile Include="Communication\Proxies\BaseProxy.cs" />
     <Compile Include="Communication\Hosts\BaseHost.cs" />
     <Compile Include="Communication\Proxies\ClientProxy.cs" />

SafeExamBrowser.Runtime/Communication/RuntimeHost.cs

@@ -30,7 +30,7 @@ namespace SafeExamBrowser.Runtime.Communication
 		public event CommunicationEventHandler ReconfigurationRequested;
 		public event CommunicationEventHandler ShutdownRequested;
 
-		public RuntimeHost(string address, IConfigurationRepository configuration, ILogger logger) : base(address, logger)
+		public RuntimeHost(string address, IConfigurationRepository configuration, IHostObjectFactory factory, ILogger logger) : base(address, factory, logger)
 		{
 			this.configuration = configuration;
 		}

SafeExamBrowser.Runtime/CompositionRoot.cs

@@ -14,6 +14,7 @@ using SafeExamBrowser.Contracts.Behaviour.OperationModel;
 using SafeExamBrowser.Contracts.Configuration;
 using SafeExamBrowser.Contracts.Logging;
 using SafeExamBrowser.Core.Behaviour.OperationModel;
+using SafeExamBrowser.Core.Communication.Hosts;
 using SafeExamBrowser.Core.Communication.Proxies;
 using SafeExamBrowser.Core.I18n;
 using SafeExamBrowser.Core.Logging;
@@ -51,7 +52,7 @@ namespace SafeExamBrowser.Runtime
 			var desktop = new Desktop(new ModuleLogger(logger, typeof(Desktop)));
 			var processFactory = new ProcessFactory(desktop, new ModuleLogger(logger, typeof(ProcessFactory)));
 			var proxyFactory = new ProxyFactory(new ProxyObjectFactory(), logger);
-			var runtimeHost = new RuntimeHost(runtimeInfo.RuntimeAddress, configuration, new ModuleLogger(logger, typeof(RuntimeHost)));
+			var runtimeHost = new RuntimeHost(runtimeInfo.RuntimeAddress, configuration, new HostObjectFactory(), new ModuleLogger(logger, typeof(RuntimeHost)));
 			var serviceProxy = new ServiceProxy(runtimeInfo.ServiceAddress, new ProxyObjectFactory(), new ModuleLogger(logger, typeof(ServiceProxy)));
 			var sessionController = new SessionController(configuration, logger, processFactory, proxyFactory, runtimeHost, serviceProxy);