Getting Error in Asmx Web Service Unit Testing

I am getting below error message while running unit test for ASMX web service

Failed MyFunction The ASP.NET Web application at 'D:\MyProjectFolder' is already configured for testing by another test run. Only one test run at a time can run tests in ASP.NET. If there are no other test runs using this Web application, ensure that the Web.config file does not contain an httpModule named HostAdapter.

i checked in web.config. below line already added in web.config

<httpModules>
  <add name="HostAdapter" type="Microsoft.VisualStudio.TestTools.HostAdapter.Web.HttpModule, Microsoft.VisualStudio.QualityTools.HostAdapters.ASPNETAdapter, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
</httpModules>