A retrievable downhole testing tool that is adapted to be temporarily installed in a well is disclosed. The retrievable downhole testing tool comprises a variable choke, a tool control unit adapted to control the variable choke, and at least two measuring sensors adapted to measure physical parameters including pressure. At least one measuring sensor is situated above the variable choke, and at least one measuring sensor is situated below the variable choke. The retrievable downhole testing tool is pre-programmed with a specified test sequence for controlling a downhole flow rate using the variable choke and for executing downhole measurements of physical parameters at specified flow periods. The specified test sequence is adapted according to a pre-defined stability criterion using the tool control unit.