Compositionality, Decompositionality and Refinement in Input/Output Conformance Testing

Abstract

We propose an input/output conformance testing theory utilizing Modal Interface Automata with Input Refusals (IR-MIA) as novel behavioral formalism for both the specification and the implementation under test. A modal refinement relation on IR-MIA allows distinguishing between obligatory and allowed output behaviors, as well as between implicitly underspecified and explicitly forbidden input behaviors. The theory therefore supports positive and negative conformance testing with optimistic and pessimistic environmental assumptions. We further show that the resulting conformance relation on IR-MIA, called modal-irioco, enjoys many desirable properties concerning componentbased behaviors. First, modal-irioco is preserved under modal refinement and constitutes a preorder under certain restrictions which can be ensured by a canonical input completion for IR-MIA. Second, under the same restrictions, modal-irioco is compositional with respect to parallel composition of IR-MIA with multi-cast and hiding. Finally, the quotient operator on IR-MIA, as the inverse to parallel composition, facilitates decompositionality in conformance testing to solve the unknown-component problem.

Compositional testing of management conformance for multi-component enterprise applications

“…To define the mpioco relation, we first formally introduce the notions of quiescence and suspension traces. Quiescence occurs in a state when no output can be provided [12]. As for the IOLTS encoding of a management protocol, quiescence occurs whenever a configuration corresponds to a state in the original protocol where no capability is provided.…”

“…The main difference between the above solutions and ours resides in the objectives and applied method, as we build upon Tretmans' I/O conformance theory [7] to test management conformance. We chose I/O conformance testing to explicitly deal with the I/O behaviour defined by management proto-cols, while still fitting black-box scenarios [7], supporting compositionality [12], and enabling implementation freedom [22].…”

“…As for (ii) fault-handling, to the best of our knowledge, our framework is the first for I/O conformance testing in multi-component applications that explicitly models faulthandling. The only other approaches explicitly including faults are those in [12,22], even if for different purposes. They indeed model explicit fault states, which constitute forbidden states used to suspend conformance testing runs to handle the case of forbidden inputs.…”

Compositional Liveness-Preserving Conformance Testing of Timed I/O Automata

“…Finally, there are several other ioco-based testing theories. Among others, mioco [33,32,31] (i.e., ioco for modality-based systems) distinguishes optional transition (which may be implemented) from mandatory transitions (which must be implemented). Furthermore, featured-ioco [9] is based on socalled featured transition systems, incorporating feature constraints to to restrict which (pairs of) transitions may be part of the same variant.…”

Efficient Computation of Invariably Safe States for Motion Planning of Self-Driving Vehicles

“…Note that in this work we do not consider the correctness of software components of self-driving vehicles with respect to their specification, as discussed in [27], [28], for example. Furthermore, we assume redundant hardware, allowing us to ignore hardware faults, e. g., as described in [29] or [30].…”