You have to remember that the production flight test is only the last procedure of a whole series of system and operational tests done on each aircraft while it is being assembled. This will include full engine and electrical & radio checks plus a test of fuel quantity & flow in a specialized facility.
The actual Production Flight Test is carried out by a minimum crew (typically Pilot, Co-pilot & FTE) who all have many hours on type and are well acquainted with the "normal" characteristics. The test includes sub-sections for takeoff, climb, descent, approach & landing where specific tests are carried out. If the aircraft is equipped with APU and/or RAT then these are also exercised as is manual deployment of gear, manual reversion etc. Post-flight the FDR & CVR will be downloaded & checked.
This is only skimming the surface - the test for even an Regional Jet is over 18 pages and only gives the outline of the tests required as the crew is expected to know most of the details!