1. A computer-implemented method, the method performed by a processor, the 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 test-space with respect to functional attributes; 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 test-space; and manipulating the covered BDD to identify one or more coverage holes, wherein a coverage hole defines a set of coverage tasks in the 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.