test: Ensuring objectId to datastore object (datastore)

The main goal of this pull request is that performed this test for testing the method that populates a datastore object with the objectId received from the sugar's environment.
If you look, you will notice that the new method I suggested getObjectId is not very important, but... I want to stress that gives better semantics and the important thing what motivated me to do that is to getEnvironment kick back, which is a method that is causing me to want to look for a way to solve it in another way, this motivated me to isolate here.
If you do not agree with this, and want to use the test anyway, I can remove getObjectId, but atomicity that it provides should always becoming useful.