1. A method, comprising: automatically decomposing a set of one or more units at a first level of a configurable hardware system design hierarchy into a set of two or more units of a lower level of the hardware system design hierarchy, wherein the set of one or more units at a first level includes one or more units dynamically instantiated at design creation time as well as at least a first unit composed of a previously instantiated hardware system composed with two or more levels of units within the hardware system design hierarchy of the previously instantiated hardware system; and individually verifying units of each hierarchy level of the hardware system design hierarchy successively from the lower levels to the first level with testbenches, wherein the sequences of test inputs for the previously instantiated hardware system are reused when testing that previously instantiated hardware system in the configurable hardware system.