1. A test optimization method occurring upon execution by a processor, the method comprising: receiving target program code identifier parameters selected by a user for identifying target program code for a user interface (UI) to be tested, and for specifying inclusion or exclusion of at least one input from an initial representative set of inputs; determining the initial representative set of inputs corresponding to the target program code to obtain an input set using the target program code identifier parameters; selecting feature groups corresponding to the input set such that each selected feature group defines a feature of the target program code that is discernable to a user of the target program code via the UI; and determining a set of optimal input combinations corresponding to the selected feature groups to obtain an optimal input combination set of mutually exclusive inputs from the input set for exhaustively testing each of the selected feature groups, wherein obtaining the optimal input combination set of mutually exclusive inputs comprises at least one of a linked gear approach that utilizes a largest size feature group from the selected feature groups and at least one unique input combination in the largest size feature group, and an unlinked gear approach that involves blocking and non-blocking inputs selected for the exhaustive testing of the selected feature groups.