Best way to test Update Operations?

[laeubi]

I have a RCP application and like to debug/test updates of the installation

I have already activated "support software installations" in the run config and I can install stuff (even though it seems not persisted), but have a problem with the update as the following code:

IQuery<IInstallableUnit> query = new UserVisibleRootQuery();
IQueryResult<IInstallableUnit> queryResult = profile.query(query, null);

always returns an empty result. I have checked that in a deployed product the same return the items of my product so in general this should work.

Is there any other option one needs to enable? Is there something PDE needs to do to make the features of a product available?