* make the test checking expected start and stop date working

  with new simulation
* simplify this test, it will be needed to extend it once
  more complex cases can be handled by the code

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@44492 20353a03-c40f-0410-a6d1-a30d3c3de9de