Can't run UWP unit tests: Test adapter sent back a result for an unknown test case. Ignoring result

Question

I'm running into an issue in running unit tests in a Universal Windows Platform unit test library. Specifically, I'm getting the following error message:

Test adapter sent back a result for an unknown test case. Ignoring result for [unit test method name]

Here are the things I've tried, but to no avail:

• Ensured the solution builds with the x86 platform; I've even tried x64 as the platform too, but the same error occurs.
• Ensured that the platform that the test runner is using matches the platform I build against (x86 or x64).
• Deleted the bin and obj folders.
• Restarted Visual Studio (numerous times).

Are there other things I can check for?

Edit: Some more environment-specific items that hopefully will shed more light on the issue:

• The unit test library project type I have is the Universal Windows Platform Unit Test library type.
• The tests do run successfully on my desktop, which is running VS2015 with Update 2 (Enterprise). However, on my laptop which is running the same version of VS, it runs into the above issue.

Answer 1

I figured out my issue. It turns out I had at one point removed the following, critical attribute from the unit test project's AssemblyInfo file:

[assembly: AssemblyMetadata("TargetPlatform", "UAP")]

Once I added it back in, the unit tests executed.

d'oh!