For anyone who would like to try it out and improve the test coverage these are the steps: 1. bzr branch lp:~simone.busoli/nunitv2/async-support-void-and-task-return-types 2. cd into the directory 3. [optional] modify the NUnitTests.v2.nunit to contain only the 4.5 core test assembly 4. build.bat test net-4.0 Of course existing runners/core cannot run the new tests, so they have to be built from the source, which is what the above steps do. I'd say that GC modes have nothing to do with this though. Simone On Tue, Oct 2, 2012 at 4:56 PM, Jv