There are many stages of this test. Basically planetflow2 is a 'chain of responsibility'. There are a set of dots and a set of arcs joining these dots, and each arc has to be tested. Specifically, the arcs are:

(i) The packet should be received by the user-space data-collection process in root context
(ii) The packet should get incorporated in one or the other flow
(iii) The flow should get serialized into the fprobe raw dumps
(iv) The logs get shipped out to PF central
(v) The logs at PF central are successfully imported into silk - and the packet seen in (i) is appropriately reflected in the database.

For now, this test supports only (i) and (ii).
It sends out a packet and checks if it shows up as a flow. If it succeeds, it means that ULOG and fprobe are running fine, which means that flows are getting collected at least on the node.