Unit testable interface based class wrappers for .NET
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 IoC.Register<IAppDomainSystem,AppDomainSystem>();//`AbcSystem` means static methods of 'Abc'
 var service = IoC.Get<HostService>();

 public class HostService()

    public HostService(IFile file, IAppDomainSystem appDomainSystem, IProcessSystem processSystem)
    _file = file;
        _appDomainSystem = appDomainSystem;
        _processSystem = processSystem;

    public void Run()
        if (_file.Exists("Daemon.exe")
        else if (_file.Exists("Daemon.dll")
         var domain = _appDomainSystem.CreateDomain("Daemon");
            dynamic daemon = domain.CreateInstanceAndUnwrap("Daemon.dll","Daemon");
             new Daemon().Start();


  • Wraps classes into other classes with interfaces which are suitable for unit testing.
  • Designed to be used with dependency injection containers.
  • Should be used with mocking libraries and corresponding automocking container extensions in tests.
  • There are frameworks which use CLR VM hooks to fake underlying implementaion of classes. These are not available for free on each platform, but is viable alternative for wrappers.
  • When used with container injection then reveals complex object which should be split according functional provided.
  • Used at least in one production desktop application.


  • No wraps for POCOs and structs like instance of DateTime, Version. But static members like DateTime.Now are covered.
  • Implicit conversion of wrappers to real object and vice versa.
  • Wrapping sender of events (not all are done yet)
  • No combined objects (e.g. File, Path, Directory into one like IO or FileSystem object containing aforementioned as properties) in compiled distribution (only samples which can be copy pasted).
  • Static and instance members in different classes. E.g. IAssemblySystem and IAssembly.
  • No Wrap word in interfaces. Wrap word in wrapping classes.
  • Wrappers for static members also include Create methods for construction of wraps instead of constructor
  • .NET 4.0, .NET 3.5 support (main target is .NET 4.0 and according Mono).
  • All classes behave like they behave on .NET/Mono counterpart.
  • One to one correspondence with real classes, casting back and forth. Close integration with no wrappers code. E.g. can convert FileStreamWrap to FileStream or Stream, AssemblyWrap to Assembly.
  • Underlying object is not public API of wrapping interface (not visible from interfaces). Explicit IWrap implementation is used.
  • Interfaces free of wrapped classes related info.
  • Interfaces into separate assemblies of implementaions



CLR VM and code weaving hooks vs wrappers

  • Wrappers reveal complex code by looking into consuctor
  • Wrappers enforce better desing
  • Wrappers are open source and can be used on any CLR
  • Hooks are easy to inject into old codebase, but wrappers sligtly harder
  • Wrappers cannot be used to hook 3rd party components
  • Wrappers add overhead during runtime, but wrappers usually wrap IO operations which take very large time relative to wrappers added overhead. If something needs to be really fast, then should go to PInvoke.
  • Wrappers go domain modelling first design.
  • Wrappers slower down start up time and hard to use without container on devices with limited resources


  • run nuget-install.bat
  • UnitWrappers.sln
  • Build in Debug or Release mode for Any Cpu
  • in SharpDevelop 5 for .NET 3.5, 4.0
  • in Xamarin Studio 5.9 for all targets
  • in VS 2015 Community with Xamarin tools for all targets
  • run pack.bat to get nuget packages
  • all code is in C# only


If massive breaking changes and fixes happen to make design more correct. This changes will be marked by renaming to NUnitWrappers. Also possible to drop UnitWrappers namespace prefix to put wrappers into BCL namespaces.


  • add Mono target install script for windows
  • Use FAKE for build system
  • Wrap all senders of events
  • Real world sample with IoC/DI, Net, IO, WCF, etc.
  • Performance(calls and object graph construction) and memory usage overhead evaluation
  • Namespace wide factories
  • Tests which check method signatures (that wraps call right underlying methods) on code or IL level
  • UnitsWrappers.GetInstance()
  • Test helpers like in http://systemioabstractions.codeplex.com
  • Virtual in memory net server.
  • Virual in memory NTFS
  • Semi-automatic migration, documenting, wrapping (using Roslyn/Mono.Cecil) of of types
  • Wrapperasing /dewraperasing existing code (using Roslyn) Prove of Concept
  • Wraperizer: add partial
  • Wraperizer: add conversion implicit coversion back and forward
  • Wraperizer: use IL reader to allow for .NET current runtime independant generation for several profiles
  • Wraperizer:use roslyn and parse WrapBase as template for mixing
  • Wraperizer: add methods
  • Wraperizer: add properites
  • Wraperizer: add events
  • Wraperizer:add options how to wrap events
  • Wraperizer:research how event patters are implement and wrap accoding patter used by underlying code
  • Wraperizer: research reading metadata from Reference Assemblies vs real assemblies
  • Wraperizer:add IDisposable
  • Wraperizer:add all unit testable interfaces implemented by wrapped object
  • Wraperizer:add depenencies wrapping (if return type or parameter are used and are wrapped then should build them before
  • Wraperizer: add contol over events (threading, error handling)
  • Wraperizer:add Component inheritance if needed
  • Wraperizer: add custom interface hook
  • Wraperizer: fix parallel hierarchies of inheritance
  • Wraperizer: add doc generation
  • Wraperizer:do call for GetType, Equals, but ToString(only if overridden in wrapped) and GetHashCode

Obsolete and new methods

Methods obsolete in .NET 4.0 or .NET 3.5 are not implemented. New .NET methods sometimes backported to 3.5 wrappers.



Total number of wraps: 60 Microsoft.Win32.Registry-> UnitWrappers.Microsoft.Win32.IRegistry : 100%

Microsoft.Win32.RegistryKey-> UnitWrappers.Microsoft.Win32.IRegistryKey UnitWrappers.Microsoft.Win32.IRegistryKeySystem : 60%

Microsoft.Win32.SafeHandles.SafeFileHandle-> UnitWrappers.Microsoft.Win32.SafeHandles.ISafeFileHandle : 90%

System.AppDomain-> UnitWrappers.System.IAppDomainSystem UnitWrappers.System.IAppDomain : 52%

System.ComponentModel.BackgroundWorker-> UnitWrappers.System.ComponentModel.IBackgroundWorker : 65%

System.Configuration.ConfigurationManager-> UnitWrappers.System.Configuration.IConfigurationManager : 75%

System.Console-> UnitWrappers.System.IConsole : 9%

System.Data.SqlClient.SqlCommand-> UnitWrappers.System.Data.SqlClient.ISqlCommand : 2%

System.Data.SqlClient.SqlConnection-> UnitWrappers.System.Data.SqlClient.ISqlConnection : 32%

System.Data.SqlClient.SqlDataReader-> UnitWrappers.System.Data.SqlClient.ISqlDataReader : 48%

System.DateTime-> UnitWrappers.System.IDateTimeSystem : 20%

System.Diagnostics.FileVersionInfo-> UnitWrappers.System.Diagnostics.IFileVersionInfoSystem UnitWrappers.System.Diagnostics.IFileVersionInfo : 50%

System.Diagnostics.Process-> UnitWrappers.System.Diagnostics.IProcess UnitWrappers.System.Diagnostics.IProcessSystem : 58%

System.Diagnostics.ProcessStartInfo-> UnitWrappers.System.Diagnostics.IProcessStartInfo : 34%

System.Diagnostics.TraceSource-> UnitWrappers.System.Diagnostics.ITraceSource : 66%

System.Environment-> UnitWrappers.System.IEnvironment : 53%

System.IO.BinaryReader-> UnitWrappers.System.IO.IBinaryReader : 88%

System.IO.BinaryWriter-> UnitWrappers.System.IO.IBinaryWriter : 85%

System.IO.Compression.DeflateStream-> UnitWrappers.System.IO.Compression.IDeflateStream : 65%

System.IO.Directory-> UnitWrappers.System.IO.IDirectory : 77%

System.IO.DirectoryInfo-> UnitWrappers.System.IO.IDirectoryInfo : 52%

System.IO.File-> UnitWrappers.System.IO.IFile : 89%

System.IO.FileInfo-> UnitWrappers.System.IO.IFileInfoSystem UnitWrappers.System.IO.IFileInfo : 58%

System.IO.FileStream-> UnitWrappers.System.IO.IFileStream : 62%

System.IO.FileSystemWatcher-> UnitWrappers.System.IO.IFileSystemWatcher : 50%

System.IO.IsolatedStorage.IsolatedStorageFile-> UnitWrappers.System.IO.IsolatedStorage.IIsolatedStorageFile : 0%

System.IO.MemoryStream-> UnitWrappers.System.IO.IMemoryStream : 64%

System.IO.Path-> UnitWrappers.System.IO.IPath : 100%

System.IO.Stream-> UnitWrappers.System.IO.IStream UnitWrappers.System.IO.IStreamSystem : 50%

System.IO.StreamReader-> UnitWrappers.System.IO.IStreamReader : 35%

System.IO.StreamWriter-> UnitWrappers.System.IO.IStreamWriter : 66%

System.IO.TextReader-> UnitWrappers.System.IO.ITextReader : 47%

System.IO.TextWriter-> UnitWrappers.System.IO.ITextWriter : 68%

System.Management.ManagementObjectSearcher-> UnitWrappers.System.Management.IManagementObjectSearcher : 6%

System.Net.Mail.SmtpClient-> UnitWrappers.System.Net.Mail.ISmtpClient : 0%

System.Net.NetworkInformation.NetworkChange-> UnitWrappers.System.Net.NetworkInformation.INetworkChange : 100%

System.Net.NetworkInformation.NetworkInterface-> UnitWrappers.System.Net.NetworkInformation.INetworkInterface : 7%

System.Net.NetworkInformation.Ping-> UnitWrappers.System.Net.NetworkInformation.IPing : 2%

System.Net.Sockets.Socket-> UnitWrappers.System.Net.Sockets.ISocket : 25%

System.Net.WebClient-> UnitWrappers.System.Net.IWebClient : 65%

System.Net.WebRequest-> UnitWrappers.System.Net.IWebRequestSystem : 8%

System.Reflection.Assembly-> UnitWrappers.System.Reflection.IAssemblySystem UnitWrappers.System.Reflection.IAssembly : 64%

System.Reflection.AssemblyName-> UnitWrappers.System.Reflection.IAssemblyName : 43%

System.Runtime.InteropServices.SafeHandle-> UnitWrappers.System.Runtime.InteropServices.ISafeHandle : 70%

System.Security.AccessControl.DirectorySecurity-> UnitWrappers.System.Security.AccessControl.IDirectorySecurity : 40%

System.Security.AccessControl.FileSecurity-> UnitWrappers.System.Security.AccessControl.IFileSecurity : 40%

System.Security.AccessControl.FileSystemSecurity-> UnitWrappers.System.Security.AccessControl.IFileSystemSecurity : 35%

System.Security.Permissions.FileIOPermission-> UnitWrappers.System.Security.Permissions.IFileIOPermission : 41%

System.Threading.AutoResetEvent-> UnitWrappers.System.Threading.IAutoResetEvent : 15%

System.Threading.Mutex-> UnitWrappers.System.Threading.IMutex UnitWrappers.System.Threading.IMutexSystem : 18%

System.Threading.Tasks.Task-> UnitWrappers.System.Threading.Tasks.ITask : 11%

System.Threading.Thread-> UnitWrappers.System.Threading.IThread UnitWrappers.System.Threading.IThreadSystem : 33%

System.Threading.ThreadPool-> UnitWrappers.System.Threading.IThreadPool : 44%

System.Threading.WaitHandle-> UnitWrappers.System.Threading.IWaitHandle UnitWrappers.System.Threading.IWaitHandleSystem : 24%

System.Timers.Timer-> UnitWrappers.System.Timers.ITimer : 28%

System.Windows.Clipboard-> UnitWrappers.System.Windows.IClipboard : 96%

System.Windows.MessageBox-> UnitWrappers.System.Windows.IMessageBox : 100%

System.Windows.Threading.Dispatcher-> UnitWrappers.System.Windows.Threading.IDispatcherSystem UnitWrappers.System.Windows.Threading.IDispatcher : 68%

System.Windows.Threading.DispatcherTimer-> UnitWrappers.System.Windows.Threading.IDispatcherTimerSystem UnitWrappers.System.Windows.Threading.IDispatcherTimer : 65%

System.Windows.Window-> UnitWrappers.System.Windows.IWindow UnitWrappers.System.Windows.IWindowSystem : 10%