No tests found to run - while debugging/running Unit test cases -- Visual studio 2017 15.5.1

Error : No tests found to run - while debugging/running C# Unit test cases -- Visual studio 2017 15.5.1 not discovering test cases.

Framework Microsoft.NET framework 4.6.1

Added Test adapters as below MSTest.TestAdapter.1.2.0 MSTest.TestFramework.1.2.0

Test explorer not showing the test cases.

This started happening after upgrading visual studio. Some unit test projects test cases do not get discovered in the test explorer. When try to debug or run it says "No tests found to run."

I tried deleting project and recreating it again .. but didn't worked.

Output [4/3/2018 2:59:25 PM Informational] No tests found to run.