1. A computer-implemented method comprising: obtaining a functional coverage model of a System Under Test (SUT) defining all functional coverage tasks of the SUT, wherein the functional coverage model defining a functional coverage test-space with respect to functional attributes, wherein the functional coverage test-space includes the all functional coverage tasks of the SUT; obtaining a set of covered functional coverage tasks; encoding a covered Binary Decision Diagram (BDD) to represent the set of covered functional coverage tasks within the functional coverage test-space; and manipulating, by a processor, the covered BDD to identify one or more coverage holes, wherein a coverage hole defines a set of functional coverage tasks in the functional coverage test-space, all having a same combination of values to a subset of the functional attributes, that are not covered by the set of covered functional coverage task.