Getting Test Results in Visual Studio Team Services (VSTS)

Important note: These directions are for testing desktop unit test assemblies only. In particular, these directions will not work for .NET Core.

Referencing the Visual Studio test runner

Using NuGet Package Manager (or Package Manager Console), add xunit.runner.visualstudio to at least one of your test projects.
install-package xunit.runner.visualstudio

Configure VSTS

Add a build step of type Visual Studio Test.

These instructions are written for Version 1.* of the Visual Studio Test task. You may need to change the version as it defaults to Version 2.* or whichever is latest.

Locate test assemblies

Under Execution Options/Test Assembly, point to your generated test assemblies, e.g. **\bin\$(BuildConfiguration)\*test*.dll;-:**\xunit.runner.visualstudio.testadapter.dll.
(The second part excludes the xUnit test adapter from being considered a test assembly.)

Enable Code Coverage (optional)

Select the Execution Options/Code Coverage Enabled checkbox.
Add /InIsolation under Advanced Execution Options/Other console options.
(This will supress a warning otherwise generated.)

Viewing the results

After a successful build, the test results are available on the main view of the build. It should look something like this:

Comments

You no longer need to manually configure the test adapter path, because Nuget restored test adapters are automatically searched for.
Sometimes you get this error one or many times
Warning: System.AppDomainUnloadedException: Attempted to access an unloaded AppDomain. This can happen if the test(s) started a thread but did not stop it. Make sure that all the threads started by the test(s) are stopped before completion.
It is not related to VSTS and does not affect the results. For more information, see xUnit Issue 490 and MS Connect.