I am currently writing a unit test framework which shall in the end run standard unit tests written in Visual Studio. The Framework is currently not working correctly with accessors. Consider the following test method:
[TestMethod()]
public void TestMethod()
{
ExampleMethods_Accessor target = null;
target = new ExampleMethods_Accessor();
target.SomeMethod();
}
In this example, the accessor has been generated by Visual Studio. The unit test works perfectly fine when run using the Unit Testing environment of Visual Studio. However, I would like to invoke the TestMethod() from within my Framework. At the line "target = new ExampleMethods_Accessor()", the following exception is thrown:
The type initializer for "Proband.ExampleMethods_Accessor" threw an excepition.
Inner exception:
Could not load file or assembly: Proband, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null...
Has anyone an idea of how the Microsoft Unit Testing Framework invokes unit tests? I was thinking it might be due to the missing TestContext object. This is "null" in my case. When starting the unit test in Visual Studio, the TestContext object contains a lot of information. Could it be, that I need to initialize it properly? How would it need to be initialized?
Thanks for all help, Christian
EDIT:
I kept experimenting with the way accessors are working. I used ILSpy to see what code is being generated into the Proband_Accessor.dll. It turns out that the instruction causing the exception is:
SomeClass_Accessor.m_privateType = new PrivateType("Probant, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null", "Probant.SomeClass");
I modified my unit test code to be like this (just for test):
[TestMethod()]
[DeploymentItem("Proband.dll")]
public void SomeMethodTest()
{
ExampleMethods_Accessor target = null;
ExampleMethods c = null;
try
{
Assembly.Load("Proband, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"); // this works fine
PrivateType tx = new PrivateType(typeof(ExampleMethods)); // this works fine as well (also without loading the assembly)
PrivateType t = new PrivateType("Proband, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null", "Proband.ExampleMethods"); // this causes the exception
c = new ExampleMethods(); // this works fine
target = new ExampleMethods_Accessor(); // this causes the exception as well
}
catch (Exception ex)
{
Console.WriteLine();
}
int actual;
actual = target.SomeMethod();
}
I do absolutely not understand, why "new PrivateType("Proband, Version...." does not work. Has anyone an idea?
I have managed to create a workaround for the issue.
To my AppDomain, I am adding an AssemblyResolveEventHandler:
AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(MyResolveEventHandler);
This event handler contains the following code:
private Assembly MyResolveEventHandler(object sender, ResolveEventArgs args)
{
if(args.Name == "Proband, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null")
{
// resolving correct assembly of type under test
return typeof(ExampleMethods).Assembly;
}
else
{
return null;
}
}
Now the line of code "target = new ExampleMethods_Accessor();" works fine and returns the correct accessor object.
I still do not understand, why the Assembly cannot be resolved automatically.
Even if it is very unlikely that anyone will have the same problem: I hope this answer helps someone :)
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