I’ve run into this problem a couple of times, but not often enough to remember it, so I’m “writing” it down here to help improve my memory.
I was trying to run a test against an ASP.Net MVC project, when I kept encountering an error, telling me the test wouldn’t run because the location of one of my DLL or the DLL itself wasn’t trusted…
What it basically was is that the DLL in question was from the internet, and Windows knows that, so it marked it as not trusted. The solution was easy, as explained here: simply navigate to the DLL in question, and click the Unblock button.
That article said “You may need to restart Visual Studio before the tests will run.” I do remember that in doing this previously, I had to restart Visual Studio every time.
Oh, and a special note: When your test project is named very similarly to your project under test—make sure you find the right file. That took me a few minutes, as I kept trying to unblock the one in my Web project, instead of my Test project. (Like I said, my two are similarly named.)
I hope that helps someone, or maybe myself if/when I hit this again.