Error mocking internal members of Trimmable assemblies on Android

[jamescrosswell]

Describe the bug Tests that use NSubstitute to mock internal members of Trimmable assemblies fail when run on Android, with the following error:

System.ArgumentException : Can not create proxy for type Sentry.IPing because it is not accessible. Make it public, or internal and mark your assembly with [assembly: InternalsVisibleTo("DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7")] attribute, because assembly Sentry is strong-named. Arg_ParamName_Name, additionalInterfacesToProxy]]

If we set <IsTrimmable>false</IsTrimmable> in the .csproj file of the code being tested then the test pass.

To Reproduce

I've provided a minimal reproducable example at:

• https://github.com/jamescrosswell/device-test-repro

The readme.md file in that repo describes how to run the tests using the included powershell script.

Expected behaviour

We'd like the tests to pass for assemblies marked with IsTrimmable. With the growth of frameworks like MAUI we're seeing more and more people wanting to trim their applications.

Environment:

• NSubstitute version: 5.1.0
• NSubstitute.Analyzers version: CSharp 1.0.17
• Platform: net8.0-android

Additional context We bumped into this in the device tests for the Sentry SDK for .NET. For the time being, I'll look at disabling trimming on the relevant assemblies for the purposes of running these device tests. Ideally we'd be able to run our tests against the same code we ship though and we ship with <IsAotCompatible>true</IsAotCompatible> (so implicitly <IsTrimmable>true</IsTrimmable>).