Mark service interfaces with [SDService].

src/Main/Base/Project/Src/Editor/IEditorControlService.cs

@@ -11,7 +11,7 @@ namespace ICSharpCode.SharpDevelop.Editor
 	/// <summary>
 	/// Allows creating new text editor instances and accessing the default text editor options.
 	/// </summary>
-	[FallbackService(typeof(EditorControlServiceFallback))]
+	[SDService(FallbackImplementation = typeof(EditorControlServiceFallback))]
 	public interface IEditorControlService
 	{
 		ITextEditor CreateEditor(out object control);

src/Main/Base/Project/Src/Gui/IWorkbench.cs

@@ -14,6 +14,7 @@ namespace ICSharpCode.SharpDevelop.Gui
 	/// <summary>
 	/// This is the basic interface to the workspace.
 	/// </summary>
+	[SDService]
 	public interface IWorkbench : IMementoCapable
 	{
 		/// <summary>

src/Main/Base/Project/Src/Services/File/IFileService.cs

@@ -15,6 +15,7 @@ namespace ICSharpCode.SharpDevelop
 	/// <summary>
 	/// File service.
 	/// </summary>
+	[SDService]
 	public interface IFileService
 	{
 		#region Options

src/Main/Base/Project/Src/Services/IMessageLoop.cs

@@ -7,11 +7,14 @@ using System.Threading;
 using System.Threading.Tasks;
 using System.Windows.Threading;
 
+using ICSharpCode.Core;
+
 namespace ICSharpCode.SharpDevelop
 {
 	/// <summary>
 	/// Represents a thread running a message loop.
 	/// </summary>
+	[SDService]
 	public interface IMessageLoop
 	{
 		/// <summary>

src/Main/Base/Project/Src/Services/ParserService/IAssemblyParserService.cs

@@ -13,6 +13,7 @@ namespace ICSharpCode.SharpDevelop.Parser
 	/// <summary>
 	/// Portions of parser service that deal with loading external assemblies for code completion.
 	/// </summary>
+	[SDService]
 	public interface IAssemblyParserService
 	{
 		IUnresolvedAssembly GetAssembly(FileName fileName, CancellationToken cancellationToken = default(CancellationToken));

src/Main/Base/Project/Src/Services/ParserService/IGlobalAssemblyCacheService.cs

@@ -3,12 +3,14 @@
 
 using System;
 using System.Collections.Generic;
+using ICSharpCode.Core;
 
 namespace ICSharpCode.SharpDevelop.Parser
 {
 	/// <summary>
 	/// Interface for global assembly cache service.
 	/// </summary>
+	[SDService]
 	public interface IGlobalAssemblyCacheService
 	{
 		/// <summary>

src/Main/Base/Project/Src/Services/ParserService/IParserService.cs

@@ -21,6 +21,7 @@ namespace ICSharpCode.SharpDevelop.Parser
 	/// <summary>
 	/// Manages parse runs and caches ParseInformation.
 	/// </summary>
+	[SDService]
 	public interface IParserService
 	{
 		/// <summary>

src/Main/Base/Project/Src/Services/StatusBar/StatusBarService.cs

@@ -11,6 +11,7 @@ using ICSharpCode.Core;
 
 namespace ICSharpCode.SharpDevelop.Gui
 {
+	[SDService]
 	public interface IStatusBarService
 	{
 		//bool Visible { get; set; }

src/Main/Core/Project/ICSharpCode.Core.csproj

@@ -107,7 +107,7 @@
     <Compile Include="Src\ExtensionMethods.cs" />
     <Compile Include="Src\Services\AnalyticsMonitorService.cs" />
     <Compile Include="Src\Services\ApplicationStateInfoService.cs" />
-    <Compile Include="Src\Services\FallbackServiceAttribute.cs" />
+    <Compile Include="Src\Services\SDServiceAttribute.cs" />
     <Compile Include="Src\Services\FileUtility\FileName.cs" />
     <Compile Include="Src\Services\FileUtility\FileNameEventHandler.cs" />
     <Compile Include="Src\Services\FileUtility\FileUtility.cs" />

src/Main/Core/Project/Src/AddInTree/IAddInTree.cs

@@ -7,6 +7,7 @@ using System.Collections.Generic;
 
 namespace ICSharpCode.Core
 {
+	[SDService]
 	public interface IAddInTree
 	{
 		/// <summary>

src/Main/Core/Project/Src/Services/AnalyticsMonitorService.cs

@@ -9,7 +9,7 @@ namespace ICSharpCode.Core
 	/// Interface for AnalyticsMonitorService.
 	/// </summary>
 	/// <remarks>Implementations of this interface must be thread-safe.</remarks>
-	[FallbackService(typeof(AnalyticsMonitorFallback))]
+	[SDService(FallbackImplementation = typeof(AnalyticsMonitorFallback))]
 	public interface IAnalyticsMonitor
 	{
 		/// <summary>

src/Main/Core/Project/Src/Services/ApplicationStateInfoService.cs

@@ -12,6 +12,7 @@ namespace ICSharpCode.Core
 	/// This service is used to summarize important information
 	/// about the state of the application when an exception occurs.
 	/// </summary>
+	[SDService]
 	public class ApplicationStateInfoService
 	{
 		readonly Dictionary<string, Func<object>> stateGetters = new Dictionary<string, Func<object>>(StringComparer.InvariantCulture);

src/Main/Core/Project/Src/Services/FallbackServiceAttribute.cs

@@ -1,62 +0,0 @@
-// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
-// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
-
-using System;
-using System.Collections.Generic;
-
-namespace ICSharpCode.Core
-{
-	/// <summary>
-	/// Used on a service interface to indicate the default implementation.
-	/// </summary>
-	[AttributeUsage(AttributeTargets.Interface, Inherited=false)]
-	public class FallbackServiceAttribute : Attribute
-	{
-		readonly string assemblyQualifiedName;
-		readonly Type fallbackServiceType;
-		
-		public FallbackServiceAttribute(Type fallbackServiceType)
-		{
-			if (fallbackServiceType == null)
-				throw new ArgumentNullException("fallbackServiceType");
-			this.fallbackServiceType = fallbackServiceType;
-		}
-		
-		public FallbackServiceAttribute(string assemblyQualifiedName)
-		{
-			if (assemblyQualifiedName == null)
-				throw new ArgumentNullException("assemblyQualifiedName");
-			this.assemblyQualifiedName = assemblyQualifiedName;
-		}
-		
-		public string AssemblyQualifiedName {
-			get { return assemblyQualifiedName ?? fallbackServiceType.AssemblyQualifiedName; }
-		}
-		
-		public Type FallbackServiceType {
-			get { return fallbackServiceType ?? Type.GetType(assemblyQualifiedName); }
-		}
-	}
-	
-	sealed class FallbackServiceProvider : IServiceProvider
-	{
-		Dictionary<Type, object> fallbackServiceDict = new Dictionary<Type, object>();
-		
-		public object GetService(Type serviceType)
-		{
-			object instance;
-			lock (fallbackServiceDict) {
-				if (!fallbackServiceDict.TryGetValue(serviceType, out instance)) {
-					var attr = serviceType.GetCustomAttributes(typeof(FallbackServiceAttribute), false);
-					if (attr.Length == 1) {
-						instance = Activator.CreateInstance(((FallbackServiceAttribute)attr[0]).FallbackServiceType);
-					} else {
-						instance = null;
-					}
-					fallbackServiceDict.Add(serviceType, instance);
-				}
-			}
-			return instance;
-		}
-	}
-}

src/Main/Core/Project/Src/Services/LoggingService/ILoggingService.cs

@@ -6,7 +6,7 @@ using ICSharpCode.Core.Implementation;
 
 namespace ICSharpCode.Core
 {
-	[FallbackService(typeof(FallbackLoggingService))]
+	[SDService(FallbackImplementation = typeof(FallbackLoggingService))]
 	public interface ILoggingService
 	{
 		void Debug(object message);

src/Main/Core/Project/Src/Services/MessageService/IMessageService.cs

@@ -9,7 +9,7 @@ namespace ICSharpCode.Core
 	/// <summary>
 	/// Interface for the MessageService.
 	/// </summary>
-	[FallbackService(typeof(FallbackMessageService))]
+	[SDService(FallbackImplementation = typeof(FallbackMessageService))]
 	public interface IMessageService
 	{
 		/// <summary>

src/Main/Core/Project/Src/Services/PropertyService/IPropertyService.cs

@@ -11,6 +11,7 @@ namespace ICSharpCode.Core
 	/// <summary>
 	/// The property service.
 	/// </summary>
+	[SDService]
 	public interface IPropertyService : INotifyPropertyChanged
 	{
 		/// <summary>

src/Main/Core/Project/Src/Services/ResourceService/IResourceService.cs

@@ -10,7 +10,7 @@ namespace ICSharpCode.Core
 	/// <summary>
 	/// Provides string and bitmap resources.
 	/// </summary>
-	[FallbackService(typeof(DummyResourceService))]
+	[SDService(FallbackImplementation = typeof(FallbackResourceService))]
 	public interface IResourceService
 	{
 		/// <summary>
@@ -59,7 +59,7 @@ namespace ICSharpCode.Core
 		void RegisterNeutralImages(ResourceManager imageManager);
 	}
 	
-	sealed class DummyResourceService : IResourceService
+	sealed class FallbackResourceService : IResourceService
 	{
 		event EventHandler IResourceService.LanguageChanged { add {} remove {} }
 		

src/Main/Core/Project/Src/Services/SDServiceAttribute.cs

@@ -0,0 +1,52 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Collections.Generic;
+
+namespace ICSharpCode.Core
+{
+	/// <summary>
+	/// Specifies that the interface is a SharpDevelop service that is accessible via <c>SD.Services</c>.
+	/// </summary>
+	/// <remarks>
+	/// This attribute is mostly intended as documentation, so that it is easily possible to see
+	/// if a given service is globally available in SharpDevelop.
+	/// </remarks>
+	[AttributeUsage(AttributeTargets.Interface | AttributeTargets.Class, Inherited=false)]
+	public class SDServiceAttribute : Attribute
+	{
+		/// <summary>
+		/// The class that implements the interface and serves as a fallback service
+		/// in case no real implementation is registered.
+		/// </summary>
+		/// <remarks>
+		/// This property is also useful for unit tests, as there usually is no real service instance when testing.
+		/// </remarks>
+		public Type FallbackImplementation { get; set; }
+	}
+	
+	sealed class FallbackServiceProvider : IServiceProvider
+	{
+		Dictionary<Type, object> fallbackServiceDict = new Dictionary<Type, object>();
+		
+		public object GetService(Type serviceType)
+		{
+			object instance;
+			lock (fallbackServiceDict) {
+				if (!fallbackServiceDict.TryGetValue(serviceType, out instance)) {
+					var attrs = serviceType.GetCustomAttributes(typeof(SDServiceAttribute), false);
+					if (attrs.Length == 1) {
+						var attr = (SDServiceAttribute)attrs[0];
+						if (attr.FallbackImplementation != null) {
+							instance = Activator.CreateInstance(attr.FallbackImplementation);
+						}
+					}
+					// store null if no fallback implementation exists
+					fallbackServiceDict.Add(serviceType, instance);
+				}
+			}
+			return instance;
+		}
+	}
+}