Bounded Sequence Testing from Non-deterministic Finite State Machines

The widespread use of

finite state machines

(

FSMs

) in modeling of communication protocols has lead to much interest in testing from (deterministic and non-deterministic) FSMs. Most approaches for selecting a test suite from a non-deterministic FSM are based on

state counting

. Generally, the existing methods of testing from FSMs check that the implementation under test behaves as specified for

all

input sequences. On the other hand, in many applications, only input sequences of limited length are used. In such cases, the test suite needs only to establish that the IUT produces the specified results in response to input sequences whose length does not exceed an upper bound

l

. A recent paper devises methods for

bounded sequence testing

from

deterministic

FSM specifications. This paper considers the, more general, situation where the specification may be a

non-deterministic FSM

and extends state counting to the case of bounded sequences. The extension is not trivial and has practical value since the test suite produced may contain only a small fraction of all sequences of length less than or equal to the upper bound.