vstest.console throws System.IO.FileNotFoundException - unit-testing

Question

My application has several unit tests projects. All other projects and the unit tests projects get built to a common output directory. With an msbuild task I'm collecting all the unit tests assemblies and run vstest.console.exe to test these assemblies.
"C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\Tools\..\IDE\CommonExtensions\Microsoft\TestWindow\vstest.console.exe" "Assembly1.UnitTest.dll" "Assembly2.UnitTest.dll" /Platform:x64 /Framework:Framework40 /InIsolation /Logger:trx
This results in an exception: System.IO.FileNotFoundException: Could not load file or assembly 'someassembly.dll' or one of its dependencies. The specified module could not be found.
When I execute vstest.console.exe for a single unit tests assembly the above exception doesn't occur. Further investigation learned me that when testing multiple assemblies at once the vstest.console is copying the test assemblies and depended assemblies to an "out" directory in the "testresults" directory. However not all needed assemblies are referenced by a project but manually copied to the common output directory. Those assemblies are missing in the "out" directory in "testresults" and causing the System.IO.FileNotFoundException.
With MSTest I could use a config file an point to the common output directory by adding a DeploymentItem. For vstest.console this doesn't work anymore.
What can I do to get around this behavior? I don't want to work with an "out" directory. Running my unit tests from the common output directory is just fine.
PS. I have the same issue on TFS 2013 with build definitions. My build definitions are collecting *.unittest.dlls and executing these with the Test Runner.

Answer 1

The solution is using a .runsettings file. In the runsettings file it is possible to specify "DeploymentEnabled". By default this is true. Changing it to false doesn't copy all the assemblies to the out directory of the TestResults directory. More information on the runsettings file: http://msdn.microsoft.com/en-us/library/jj635153.aspx.
Example:
<?xml version="1.0" encoding="utf-8"?>
<RunSettings>
<!--Info: http://msdn.microsoft.com/en-us/library/jj635153.aspx -->
<MSTest>
<IgnoreTestImpact>True</IgnoreTestImpact>
<MapInconclusiveToFailed>True</MapInconclusiveToFailed>
<CaptureTraceOutput>False</CaptureTraceOutput>
<DeleteDeploymentDirectoryAfterTestRunIsComplete>True</DeleteDeploymentDirectoryAfterTestRunIsComplete>
<DeploymentEnabled>False</DeploymentEnabled>
</MSTest>
</RunSettings>