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Tudor Bălănescu 《Formal Aspects of Computing》2000,12(6):473-484
Some conditions relating to the automata involved in the W-testing method are discussed. It is also shown how to use the
method for reduced automata instead of minimal automata. New design test conditions (weak output distinguishable, strong test-complete and output delimited type) are considered for the generalised stream X-machines (stream X-machines with basic functions replaced by relations and having as output strings of symbols rather than single
symbols). It is proved that testing methods similar to those already developed for ordinary deterministic stream X-machines
may be applied for generalised stream X-machines with output delimited types. A particular case of generalised stream X-machine
with output delimited type is the X-machine with output delimiter, which produces outputs having a distinct right end character.
Received October 2000 / Accepted in revised form January 2001 相似文献
2.
X-machines were proposed by Holcombe as a possible specification language and since then a number of further investigations
have demonstrated that the model is intuitive and easy to use as well as general enough to cater for a wide range of applications.
In particular (generalised) stream X-machines have been found to be extremely useful as a specification method and most of
the theory developed so far has concentrated on this particular class of X-machines. Furthermore, a method for testing systems
specified by stream X-machines exists and is proved to detect all faults of the implementation provided that the system meets
certain initial requirements. However, this method can only be used to generate test sequences from deterministic X-machine
specifications. In this paper we present the theoretical basis for a method for generating test sets from non-deterministic
generalised stream X-machines.
Received November 1999 / Accepted in revised form September 2000 相似文献
3.
Marian Gheorghe 《Formal Aspects of Computing》2000,12(6):459-472
Stream X-machines are a general and powerful computational model. By coupling the control structure of a stream X-machine
with a set of formal grammars a new machine called a generalised stream X-machine with underlying distributed grammars, acting as a translator, is obtained. By introducing this new mechanism a hierarchy of computational models is provided.
If the grammars are of a particular class, say regular or context-free, then finite sets are translated into finite sets,
when ?k, = k derivation strategies are used, and regular or context-free sets, respectively, are obtained for ?k, * and terminal derivation strategies. In both cases, regular or context-free grammars, the regular sets are translated into non-context-free
languages. Moreover, any language accepted by a Turing machine may be written as a translation of a regular set performed
by a generalised stream X-machine with underlying distributed grammars based on context-free rules, under = k derivation strategy. On the other hand the languages generated by some classes of cooperating distributed grammar systems
may be obtained as images of regular sets through some X-machines with underlying distributed grammars. Other relations of
the families of languages computed by generalised stream X-machines with the families of languages generated by cooperating
distributed grammar systems are established. At the end, an example dealing with the specification of a scanner system illustrates
the use of the introduced mechanism as a formal specification model.
Received September 1999 / Accepted in revised form October 2000 相似文献
4.
One of the strengths of using stream X-machines to specify a system is that, under certain well defined conditions, it is possible to produce a test set that is guaranteed to determine the correctness of an implementation. However, the existing method assumes that the implementation of each processing function is proved to be correct before the actual testing can take place, so it only test the system integration. This paper presents a new method for generating test sets from a deterministic stream X-machine specification that generalises the existing integration testing method. This method no longer requires the implementations of the processing functions to be proved correct prior to the actual testing. Instead, the testing of the processing functions is performed along with the integration testing.Accepted in revised form 27 February 2004 by D.A. Duce 相似文献
5.
This paper presents a new model for passing messages in communicating stream X-machine systems (CSXMS). The components are
stream X-machines with ε-transitions, acting simultaneously. The states are partitioned into processing and communicating
states. Passing messages between the X-machines involves only communicating states. A communication matrix is used as a common
memory. It is shown that a structured way of using channels, namely via select constructs with guarded alternatives and terminate clause, may be implemented. An automatic scheme for writing concurrent programs in an Ada-like style, starting from a CSXMS,
is proposed.
Received December 1999 / Accepted in revised form January 2001 相似文献
6.
The X-machine testing method has been developed as an application of the W-method to testing the control structure of an implementation,
against a specification. The method was proven to demonstrate the equivalence of the behaviour of the two, subject to a number
of conditions both a specification and an implementation are expected to satisfy, such as (1) determinism of the two and (2)
that functions labelling arcs on a transition diagram of a specification control structure have been tested in advance. Since
the original publication of the testing method, a number of extensions have been published, removing the restrictions mentioned
above. This paper surveys the extensions of the X-machine testing method, for (1) testing of functions together with testing
of a transition diagram, (2) equivalence testing of a non-deterministic implementation against a non-deterministic specification,
(3) conformance testing of a deterministic implementation against a non-deterministic specification and (4) equivalence testing
of a system of concurrently executing and communicating X-machines, against a specification.
Received June 2004
Revised March 2005
Accepted March 2005 by J. Derrick, M. Harman and R. M. Herons 相似文献
7.
X-machines were proposed by Holcombe as a possible specification language and since then a number of further investigations
have demonstrated that the model is intuitive and easy to use. In particular, stream X-machines (SXM), a particular class of X-machines, have been found to be extremely useful in practice. Furthermore, a method of testing
systems specified as SXMs exists and is proved to detect all faults of the implementation provided that the system meets certain
“design for test conditions”. Recently, a system of communicating SXMs was introduced as a means of modelling parallel processing. This paper proves that each communicating machine component can
be transformed in a straightforward manner so that the entire system will behave like a single stream X-machine - the equivalent
SXM of the system. The paper goes on to investigate the applicability of the SXM testing method to a system of communicating
SXMs and identifies a class of communicating SXMs for which the equivalent SXM of the system meets the “design for test conditions”.
Received November 1999 / Accepted in revised form June 2001 相似文献
8.
Robert M. Hierons 《Theoretical computer science》2010,411(37):3372-3385
Stream X-machines are a state based formalism that has associated with it a particular development process in which a system is built from trusted components. Testing thus essentially checks that these components have been combined in a correct manner and that the orders in which they can occur are consistent with the specification. Importantly, there are test generation methods that return a checking experiment: a test that is guaranteed to determine correctness as long as the implementation under test (IUT) is functionally equivalent to an unknown element of a given fault domain Ψ. Previous work has show how three methods for generating checking experiments from a finite state machine (FSM) can be adapted to testing from a stream X-machine. However, there are many other methods for generating checking experiments from an FSM and these have a variety of benefits that correspond to different testing scenarios. This paper shows how any method for generating a checking experiment from an FSM can be adapted to generate a checking experiment for testing an implementation against a stream X-machine. This is the case whether we are testing to check that the IUT is functionally equivalent to a specification or we are testing to check that every trace (input/output sequence) of the IUT is also a trace of a nondeterministic specification. Interestingly, this holds even if the fault domain Ψ used is not that traditionally associated with testing from a stream X-machine. The results also apply for both deterministic and nondeterministic implementations. 相似文献
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