VSTS Build fails running NUnit tests
<p>When building a visual studio solution using visual studio team services it runs the unit tests, written in nunit 3 using the nunit 3 NUnit3TestAdapter it starts running the tests.</p>

<p>The error it gives is: <em>Error: Illegal characters in path.</em></p>

<p>The complete output as follows</p>

<pre><code>2016-02-11T17:02:40.8514411Z Executing the powershell script: C:\BuildAgent\tasks\VSTest\1.0.29\VSTest.ps1
2016-02-11T17:02:41.1483135Z ##[debug]Calling Invoke-VSTest for all test assemblies
2016-02-11T17:02:41.2108131Z Working folder: C:\BuildAgent\_work\5
2016-02-11T17:02:41.2108131Z Executing C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\CommonExtensions\Microsoft\TestWindow\vstest.console.exe "C:\BuildAgent\_work\5\s\xxxxxxxxxxTests\bin\Release\xxxxxxxxxxTests.dll"  /logger:trx /TestAdapterPath:"C:\BuildAgent\_work\5\s"
2016-02-11T17:02:41.5240692Z Microsoft (R) Test Execution Command Line Tool Version 14.0.24720.0
2016-02-11T17:02:41.5240692Z Copyright (c) Microsoft Corporation.  All rights reserved.
2016-02-11T17:02:42.1326930Z Starting test execution, please wait...
2016-02-11T17:02:46.4921857Z Information: NUnit Adapter 3.0.8.0 executing tests is started
2016-02-11T17:02:46.5077303Z Information: Running all tests in C:\BuildAgent\_work\5\s\xxxxxxxxxxTests\bin\Release\xxxxxxxxxxTests.dll
2016-02-11T17:02:46.6327336Z Information: NUnit Adapter 3.0.8.0 executing tests is finished
2016-02-11T17:02:46.6327336Z ##[error]Error: Exception System.ArgumentException, Exception thrown executing tests
2016-02-11T17:02:46.6327336Z ##[error]
2016-02-11T17:02:46.6327336Z ##[error]Error: Illegal characters in path.
2016-02-11T17:02:46.6327336Z ##[error]
2016-02-11T17:02:46.7108474Z Information: Additionally, you can try specifying '/UseVsixExtensions' command if the test discoverer &amp; executor is installed on the machine as vsix extensions and your installation supports vsix extensions. Example: vstest.console.exe myTests.dll /UseVsixExtensions:true
2016-02-11T17:02:46.8358887Z ##[error]VSTest Test Run failed with exit code: 1
2016-02-11T17:02:46.8514965Z ##[warning]No results found to publish.
</code></pre>

<p>We have an on premise build agent but I don't think this should make an difference.</p>

<p><a href="https://i.stack.imgur.com/ZfDXs.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ZfDXs.png" alt="Build test step screenshot"></a></p>

<p>Any advice you can give it appreciated.</p>