System.Security.VerificationException: Operation could destabilize the runtime during code coverage run in visual studio

Question

I have a unit test that basically does the following:
Creates an app domain using minimum priviledges.  The MarshalByRefObject that is living in the app domain, loads another assembly to execute.  This new assembly basically takes in a data object defined in a separate assembly, and returns a
new data object of that type.
All this works fine in debug mode, or when running w/out code coverage.  The Sandbox assembly is signed.
The exception that gets thrown is this:
Test method TestProject1.UnitTest1.TestMethod1 threw exception:
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Security.VerificationException: Operation could destabilize the runtime.
ClassLibrary3.Bar..ctor()
ClassLibrary2.Foo.TestMethod(Bar testBar)
System.RuntimeMethodHandle._InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
System.RuntimeMethodHandle.InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
ClassLibrary1.RemoteSandBox.Execute(String assemblyPath, String scriptType, String method, Object[] parameters)
ClassLibrary1.RemoteSandBox.Execute(String assemblyPath, String scriptType, String method, Object[] parameters)
ClassLibrary1.SandBox.Execute(String assemblyPath, String scriptType, String method, Object[] parameters) in c:\users\la22426\documents\visual studio 2010\Projects\TestProject1\ClassLibrary1\Sandbox.cs: line 43
TestProject1.UnitTest1.TestMethod1() in c:\users\la22426\documents\visual studio 2010\Projects\TestProject1\TestProject1\UnitTest1.cs: line 21
Unit Test code:
[TestClass]
public class UnitTest1
[TestMethod]
public void TestMethod1()
using (SandBox sandbox = new SandBox())
string assemblyLocation = Path.Combine(Environment.CurrentDirectory, @"..\..\..\ClassLibrary2\bin\Debug\ClassLibrary2.dll");
object result = sandbox.Execute(assemblyLocation, "ClassLibrary2.Foo", "TestMethod", new Bar() { X = "test" });
Assert.IsNotNull(result);
Data Object code:
namespace ClassLibrary3
[Serializable]
public class Bar
public Bar() { }
public string X { get; set; }
Assembly to execute code:
namespace ClassLibrary2
public class Foo
public Bar TestMethod(Bar testBar)
return new Bar() { X = testBar.X };
Sandbox code:
namespace ClassLibrary1
public class SandBox : IDisposable
AppDomain Domain { get; set; }
RemoteSandBox RemoteSandBox { get; set; }
public SandBox()
var setup = new AppDomainSetup()
ApplicationBase = AppDomain.CurrentDomain.BaseDirectory,
ApplicationName = Guid.NewGuid().ToString(),
DisallowBindingRedirects = true,
DisallowCodeDownload = true,
DisallowPublisherPolicy = true,
//DisallowApplicationBaseProbing = true,
var permissions = new PermissionSet(PermissionState.None);
permissions.AddPermission(new SecurityPermission(SecurityPermissionFlag.Execution));
permissions.AddPermission(new ReflectionPermission(PermissionState.Unrestricted));
this.Domain = AppDomain.CreateDomain(setup.ApplicationName, null, setup, permissions,
typeof(RemoteSandBox).Assembly.Evidence.GetHostEvidence<StrongName>());
this.RemoteSandBox = (RemoteSandBox)Activator.CreateInstanceFrom(this.Domain, typeof(RemoteSandBox).Assembly.ManifestModule.FullyQualifiedName, typeof(RemoteSandBox).FullName).Unwrap();
public object Execute(string assemblyPath, string scriptType, string method, params object[] parameters)
return this.RemoteSandBox.Execute(assemblyPath, scriptType, method, parameters);
public void Dispose()
if (this.Domain != null)
AppDomain.Unload(this.Domain);
class RemoteSandBox : MarshalByRefObject
public RemoteSandBox()
public object Execute(string assemblyPath, string scriptType, string method, params object[] parameters)
//we need some file io permissions to load the assembly
new FileIOPermission(FileIOPermissionAccess.Read | FileIOPermissionAccess.PathDiscovery, assemblyPath).Assert();
Assembly assembly;
try
assembly = Assembly.LoadFile(assemblyPath);
finally
CodeAccessPermission.RevertAssert();
Type type = assembly.GetType(scriptType, true);
MethodInfo methodInfo = type.GetMethod(method);
object instance = (methodInfo.IsStatic) ? null : Activator.CreateInstance(type);
object returnVal = null;
returnVal = methodInfo.Invoke(instance, parameters);
return returnVal;

Answer 1

I marked the shared data library with the attributes:
[assembly: AllowPartiallyTrustedCallers]
[assembly: SecurityRules(SecurityRuleSet.Level2, SkipVerificationInFullTrust = true)]
And then marked  the data class Bar with the attribute:
[SecuritySafeCritical]
And got a little more insight into what's going on:
Test method TestProject1.UnitTest1.TestMethod1 threw exception:
System.MethodAccessException: Attempt by security transparent method 'Microsoft.VisualStudio.Coverage.Init_d2f466df4c65e2a7bb5d7592c49efef0.Register()' to call native code through method 'Microsoft.VisualStudio.Coverage.Init_d2f466df4c65e2a7bb5d7592c49efef0.VSCoverRegisterAssembly(UInt32[],
System.String)' failed.  Methods must be security critical or security safe-critical to call native code.
Microsoft.VisualStudio.Coverage.Init_d2f466df4c65e2a7bb5d7592c49efef0.Register()
ClassLibrary3.Bar..ctor() in c:\users\xxx\documents\visual studio 2010\Projects\TestProject1\ClassLibrary3\Bar.cs: line 13
TestProject1.UnitTest1.TestMethod1() in c:\users\xxx\documents\visual studio 2010\Projects\TestProject1\TestProject1\UnitTest1.cs: line 21
Since the injected code coverage il is doing some native stuff, it's throwing.  Any ideas on how to allow this?