A new approach based on using alternative graphs (AG) to create tools for computer aided test pattern design for digital systems is proposed. Different representation levels of digital systems (behavioral, procedural, functional, logical and topological ones) are supported by uniform test design tools based on the same AG-formalism. Instead of using different libraries of component models for solving different test design tasks (fault analysis, test synthesis, multivalued simulation, testability analysis), only a single library of AGs will be used, which reduces the cost of creating and updating component libraries. Aoverview of the model and methods is given and a description of a system for automated test program generation is described.