xunit.net ASP.NET vNext tests run from VS don't save output to xml

I have the following preconditions:

1. Visual Studio 2015 Community, dnx version 1.0.0-beta5
2. ASP.NET vNext project
3. ASP.NET vNext project with unit-tests (further: Unit-test project)

4. project.json in Unit-test project

   "frameworks": {
   "dnx451": {
      "dependencies": {
      "xunit": "2.1.0-beta3-*",
      "xunit.runner.dnx": "2.1.0-beta3-*",
      "xunit.abstractions": "2.0.0",
      "Moq": "4.2.1507.118",
       }
    }
   },
   "commands": {
   "test": "xunit.runner.dnx -xml TestResults.xml"
   },
   
   

When I run tests within Visual Studio, a new file TestResults.xml is created, but it is empty (except for

<?xml version="1.0" encoding="utf-8"?>
<assemblies>
  <assembly />
</assemblies>

When I run the command dnx . test -xml TestResults.xml from cmd, I get the xml file with results. What should I do to obtain the same result if run tests from Visual Studio?