| 1. |
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| 2. |
- Blom, Johan, et al.
(author)
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Industrial Evaluation of Test Suite Generation Strategies for Model-Based Testing
- 2016
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Conference paper (peer-reviewed)abstract
- We report on a case study on model based testing for a commercially available telecom software system. A main purpose is to investigate how different strategies for test suite generation affect quality attributes of the generated test suites, in a realistic industrial environment. We develop a functional model in the form of an extended finite state machine, from which we generate test suites using several different (model) coverage criteria, alongside with randomly and manually generated test suites. We compare test suites with respect to fault-detection capability, incurred (source) code coverage, and test generation and execution time. The system under test is a commercially released version, not seeded with any faults, implying that exposed faults are "real" faults that passed previous testing. We did not find clear difference between coverage-based and random test suites. Test suite generation and execution is performed using the tool ERLY MARSH, developed by the first author.
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| 3. |
- Blom, Johan, 1966-
(author)
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Model-Based Protocol Testing in an Erlang Environment
- 2016
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Doctoral thesis (other academic/artistic)abstract
- Testing is the dominant technique for quality assurance of software systems. It typically consumes considerable resources in development projects, and is often performed in an ad hoc manner. This thesis is concerned with model-based testing, which is an approach to make testing more systematic and more automated. The general idea in model-based testing is to start from a formal model, which captures the intended behavior of the software system to be tested. On the basis of this model, test cases can be generated in a systematic way. Since the model is formal, the generation of test suites can be automated and with adequate tool support one can automatically quantify to which degree they exercise the tested software.Despite the significant improvements on model-based testing in the last 20 years, acceptance by industry has so far been limited. A number of commercially available tools exist, but still most testing in industry relies on manually constructed test cases.This thesis address this problem by presenting a methodology and associated tool support, which is intended to be used for model-based testing of communication protocol implementations in industry. A major goal was to make the developed tool suitable for industrial usage, implying that we had to consider several problems that typically are not addressed by the literature on model-based testing. The thesis presents several technical contributions to the area of model-based testing, including- a new specification language based on the functional programming language Erlang,- a novel technique for specifying coverage criteria for test suite generation, and- a technique for automatically generating test suites.Based on these developments, we have implemented a complete tool chain that generates and executes complete test suites, given a model in our specification language. The thesis also presents a substantial industrial case study, where our technical contributions and the implemented tool chain are evaluated. Findings from the case study include that test suites generated using (model) coverage criteria have at least as good fault-detection capability as equally large random test suites, and that model-based testing could discover faults in previously well-tested software where previous testing had employed a relaxed validation of requirements.
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| 4. |
- Nyström, Sven-Olof
(author)
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Subtyping and Algebraic Data Types
- 2015
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Reports (other academic/artistic)abstract
- We present a new method for type inference. Traditional approaches rely on an inductively defined domain of types. Instead, we specify the properties of the type system as a set of axioms, and give a polynomial-time algorithm for checking whether there is any domain of types for which the program types. We show the correctness of the algorithm and also prove that safety properties are satisfied; any program accepted by the type system will not cause type errors at run-time. The advantages of our approach is that is simpler and more general. The algorithm for checking that a program types is a simple mechanism for propagating type information which should be easy to extend to support other programming language features. The type checking algorithm is more general than other approaches as the algorithm will accept any program that types under any type system that satisfies the axioms. We also show how to make type information available to compilers and other development tools through an algorithm to determine entailment. The language we consider is lambda calculus extended with a constructors and a form of type construct we call \emphopen case expressions. Open case expressions allow a program to manipulate abstract data types where the sets of constructors overlap.
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| 5. |
- Nyström, Sven-Olof
(author)
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Subtyping, consistency and derivability
- 2014
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Reports (other academic/artistic)abstract
- Earlier work on subtyping has focused on the problem of constructing a typing for a given program. This paper considers a slightly different problem: Given a lambda term, is the corresponding constraint system \emphconsistent? An O(n^3) algorithm for checking the consistency of constraint systems is presented, where n is the size of the constraint system. The paper also considers the problem of \emphderivability, i.e., whether a property can be derived from the corresponding constraint system and gives an O(n^3) algorithm for checking derivability of a class of constraints.
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| 6. |
- Nyström, Jan Henry, 1968-
(author)
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Analysing Fault Tolerance for Erlang Applications
- 2009
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Doctoral thesis (other academic/artistic)abstract
- ERLANG is a concurrent functional language, well suited for distributed, highly concurrent and fault-tolerant software. An important part of Erlang is its support for failure recovery. Fault tolerance is provided by organising the processes of an ERLANG application into tree structures. In these structures, parent processes monitor failures of their children and are responsible for their restart. Libraries support the creation of such structures during system initialisation.A technique to automatically analyse that the process structure of an ERLANG application from the source code is presented. The analysis exposes shortcomings in the fault tolerance properties of the application. First, the process structure is extracted through static analysis of the initialisation code of the application. Thereafter, analysis of the process structure checks two important properties of the fault handling mechanism: 1) that it will recover from any process failure, 2) that it will not hide persistent errors.The technique has been implemented in a tool, and applied it to several OTP library applications and to a subsystem of a commercial system the AXD 301 ATM switch.The static analysis of the ERLANG source code is achieved through symbolic evaluation. The evaluation is peformed according to an abstraction of ERLANG’s actual semamtics. The actual semantics is formalised for a nontrivial part of the language and it is proven that the abstraction of the semantics simulates the actual semantics.
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| 7. |
- Nyström, Sven-Olof
(author)
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Ideas for a new Erlang
- 2009
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Reports (other academic/artistic)abstract
- This paper presents some thoughts and ideas on the future development of Erlang. Among the topics are: an alternative to Erlang's selective receive, a simple language mechanism to allow function in-lining across module boundaries, a new mechanism for introducing local variables with a more cleanly defined semantics, and a mini-language to allow the efficient implementation of low-level algorithms.
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| 8. |
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| 9. |
- Nyström, Sven-Olof
(author)
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A Polyvariant Type Analysis for Erlang
- 2003
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Reports (other academic/artistic)abstract
- This paper presents a type analysis for the programming language Erlang. The analysis computes interprocedural control-flow and data-flow information, and should be applicable to any higher-order functional programming language with call-by-value semantics. The analysis uses a novel method for polyvariance, \emphstatic limiting, where an approximation of the call graph is analyzed to determine whether a function should be treated as polyvariant or monovariant. A general framework for polyvariant analysis is presented. This framework is used for experimental investigations to evaluate the cost and potential benefits of polyvariant analysis and to compare different approaches to polyvariant analysis. The experimental results show that static limiting gives the same or better precision as the other polyvariant analyses, while having more predictable analysis times. However, the experiments show only small improvements in precision for the various polyvariant analyses.
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| 10. |
- Nyström, Sven-Olof
(author)
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A soft-typing system for Erlang
- 2003
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In: Proceedings of the 2003 ACM SIGPLAN workshop on Erlang. - 1581137729 ; , s. 56-71
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Conference paper (peer-reviewed)abstract
- This paper presents a soft-typing system for the programming language Erlang. The system is based on two concepts; a (forward) data flow analysis that determines upper approximations of the possible values of expressions and other constructs, and a specification language that allows the programmer to specify the interface of a module. We examine the programming language Erlang and point to various aspects of the language that make it hard to type. We present experimental result of applying the soft-typing system to some previously written programs.
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