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Running MSTest in partial trust from Visual Studio

I like being able to run MSTest in partial trust. This would allow me to configure that the code that my modulation calls cause may not be able to do.

The problem I'm trying to solve is to allow automatic (single) tests to fail when things like the file system, database, system clock, and other external resources are used. By performing partial trust, I can configure actions that AppDomain may and may not perform. This allows me to detect places in the code that incorrectly abstract from the resources used.

If there are other ways to achieve this, please let me know.

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Unfortunately, MSTest does not have a built-in mechanism for this, and changes to the CAS policy application in .NET 4.0 severely limited the supported approaches for this.

The simplest approach to this would be to restrict the permission of the CAS permission on the AppDomain created by MSTest to run tests in a specific test assembly. However, current versions of MSTest do not allow you to intercept and / or configure the creation of AppDomain. We cannot get around this by adding code to the AssemblyInitialize method, because changes to the AppDomain policy made after running the code in AppDomain have no effect.

This basically leaves us with one supported mechanism for applying CAS permission restrictions for testing: using PermissionSet.PermitOnly from the test method or code that calls the test method. eg:.

[TestMethod] public void SomeTest() { SomeStaticTestUtilityClass.TargetPermissionSet.PermitOnly(); // Run the rest of your test code here. }

This can be done using custom test attributes using the approach described at http://blogs.msdn.com/b/vstsqualitytools/archive/2009/09/04/extending-the-visual-studio-unit-test-type- part-1.aspx . However, I have not tested this, and I am not sure that the mechanism for invoking the testing method will allow PermitOnly to be applied in such a way that it is present in the call stack for the tested code.

If you have a lot of them, so that the author and use of custom ITestMethodInvoker either does not work or otherwise does not work, another option is to use a post compiler such as PostSharp to insert PermitOnly calls.

If this does not work and you are not married to MSTest, you may also need to change your test environment to a more flexible one.

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Source: https://habr.com/ru/post/1335279/

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