I have a Visual Studio Unittest-Adapter which is working well for Visual Studio 2013 so far. Tests are extracted using a custom command ctest -N and thus a implementation of ITestContainerDiscoverer is needed.
You can check out the project here: https://github.com/micst/CTestTestAdapter
As it seems, Visual Studio 2015 simply ignores the ITestContainerDiscoverer implementation or at least never instantiates and uses it. If I remove the container discoverer from my project and add the default file extensions .dll and .exe to the ITestDiscoverer, so the VSIX in general is correctly installed and working.
How can I get the ITestContainerDiscoverer to be executed?
Ok, after some (re)search I managed to solve my problem:
1.
There is one unittest adapter example for XML files out there which works on VS2015, so I was able to track down my problem: http://blogs.msdn.com/b/bhuvaneshwari/archive/2012/03/13/authoring-a-new-visual-studio-test-adapter.aspx
2.
It seems like the signature of the constructor of my ITestContainerDiscoverer was wrong. While my original test container discoverer had a constructor without any parameters, the one used in the XML example used a bunch of parameters. After some testing it seems like you need at least a IServiceProvider as constructor parameter:
public CTestContainerDiscoverer(
[Import(typeof (SVsServiceProvider))] IServiceProvider serviceProvider)
{
No idea why exactly, but I think this solved it. It's actually quite sad how bad the documentation for the unittest adapter interfaces is.