n-Complete test suites for IOCO

An n-complete test suite for automata guarantees to detect all faulty implementations with a bounded number of states. We propose a construction of such a test suite for ioco conformance on labeled transition systems, which we derive from construction methods for deterministic FSMs. Our resulting test suite poses no further restrictions on the implementations other than their number of states and fairness in test execution. This elevates restrictions made in existing methods. In particular, we address the problem of compatible states: specification states which can be implemented by a single state. Such states are forbidden by existing methods for ioco, as they complicate test suite construction.