I have in the past posted about developing SharePoint web parts without having to use a SharePoint server by using Typemock Isolator. This technique relies on using Cassini or IIS Express as the web server to host the aspx page that in turn contains the webpart. This is all well and good for SharePoint 2007, but we get a problem with SharePoint 2010 which seems to be due to 32/64bit issues.

Working with SharePoint 2007 assemblies when SharePoint 2010 assemblies are in the GAC 

I started this adventure with a SharePoint 2007 webpart solution setup as discussed in my previous post. In this solution’s web test harness I was only referencing the SharePoint 2007 Microsoft.Sharepoint.dll. This had been working fine on a PC that had never had SharePoint installed, the required DLL was loaded from a local solution folder of SharePoint assemblies.

This was until I installed SharePoint 2010 onto my Windows 7 development PC (a great way to do SharePoint development). This put the SharePoint 2010 assemblies into the GAC. So now when I ran my Sharepoint 2007 test harness I got the error

Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.
Compiler Error Message: CS1705: Assembly ‘Microsoft.SharePoint, Version=, Culture=neutral, PublicKeyToken=71e9bce111e9429c’ uses ‘Microsoft.SharePoint.Library, Version=, Culture=neutral, PublicKeyToken=71e9bce111e9429c’ which has a higher version than referenced assembly ‘Microsoft.SharePoint.Library, Version=, Culture=neutral, PublicKeyToken=71e9bce111e9429c’

The solution is fairly simple, assuming you want work with the 2007 assemblies. All you need to do is make sure the test harness project also references the 2007 Microsoft.Sharepoint.library.dll so it does not pickup version in the GAC.


Once this is done the 2007 based test harness worked again

But what about using 2010 assemblies?

If you want to work against SharePoint 2010 assemblies there are other problems. If you just reference the 2010 Microsoft.sharepoint.dll you get the error

Could not load file or assembly ‘Microsoft.Sharepoint.Sandbox’ or one of its dependencies. An attempt was made to load a program with an incorrect format

As I said, on my PC I now have a SharePoint local installation, so I have the SharePoint 2010 assemblies in the GAC. It is from here the test harness tries to load the Microsoft.Sharepoint.Sandbox.dll assembly. The problem is that this is not a standard MSIL assembly but a 64bit one. The default Cassini development web server is 32bit. Hence the incorrect format error, the WOW64 technology behind the scenes cannot manage the loading. The only option is to use a 64bit web server to address the problem; so this rules out Cassini and IIS Express at this time as these are 32bit only.

A possible solution is to use the full IIS 7.5 installation available with Windows7, as this must be 64bit as it is able to run SharePoint 2010. The problem here is that when you load the test harness you get the error

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: TypeMock.TypeMockException:
*** Typemock Isolator is not currently enabled.
To enable do one of the following:
* To run Typemock Isolator as part of an automated process you can:
- run tests via TMockRunner.exe command line tool
- use ‘TypeMockStart’ tasks for MSBuild or NAnt
* To work with Typemock Isolator inside Visual Studio.NET:
set Tools->Enable Typemock Isolator from within Visual Studio
For more information consult the documentation (see ‘Running’ topic)

This is because this IIS instance is not under the control of Visual Studio and so it cannot start Isolator for you. To get round this you have to start Isolator manually, maybe you could do it in your test harness pages. However, you also have to remember that you if you want to debug against this IIS instance you must run Visual Studio as administrator – OK this will work, but I don’t like any of this. I really do try not to run as administrator these days.

So what we need is a 64bit web server. The best option appears to be http://cassinidev.codeplex.com. This can be used as a direct replacement for Cassini. This is still a 32bit build by default, but if you pull the source down you can change this. You need to change all the projects from x86 to Any CPU, rebuild and copy the resultant EXE and DLLs over the Cassini installation. I recommend you copy the 32bit release build over first to get the right .config files in place. You probably don’t want to use the ones from the source code zip.

Once this is all done you have a web server that can load 32bit and 64bits without issue. So for my test project I referenced the SharePoint 2010 assemblies (I maybe could have referenced less, but this works)


So we have a workaround, once setup it is used automatically. It is just a shame that the default web servers are all set to be x86 as opposed to Any CPU.