Solving Resharper “Unit Test Runner failed to load test assembly” error

recently working in my project I got this error of resharper when I tried to run/debug unittest

System.TypeLoadException: Method 'get_SolutionDirectory' in type 'JetBrains.ReSharper.UnitTestRunner.MSTest.RunContext' from assembly 'JetBrains.ReSharper.UnitTestRunner.MSTest11.Impl, Version=, Culture=neutral, PublicKeyToken=1010a0d8d6380325' does not have an implementation.

What I was using ?
Visual studio 2012 Update 4
Resharper 7.0.9
windows 8.1 pro

after Searching on google for some time I found that this problem is with resharper version 7.0.XX

So I just upgraded to 7.1.3 (free upgrade if you have resharper 7.0.XX license)

Click here to download new version of resharper.