1. Automatic test equipment, used to develop and execute a test program for verifying a circuit under test, comprising: means for inputting data, including data for specifying a hierarchical tree of nodes, the tree of nodes including a root node and at least one group of end nodes descending from the root node wherein each end node corresponds with one of a plurality of steps in the test program, at least one end node communicating with an instrument driver for controlling a test instrument, and wherein the at least one group of end nodes corresponds with steps relating to a type of test to be performed on the electronic circuit; programmable computer means coupled to the means for inputting data, including processing means responsive to the input data for producing graphic data representing the tree of nodes and execution means for executing, following a sequence prescribed by the tree of nodes, the steps in the test program; and graphic display means, coupled to the computer means, the display means being responsive to the graphic data for displaying an image of the tree of nodes.