mutation17 Paolo Arcaini Angelo Gargantini Elvinia Riccobene

MutRex: a mutation-based generator of fault detecting strings for regular expressions

in The 12th International Workshop on Mutation Analysis - 2017 IEEE International Conference on Software Testing, Verification and Validation Workshops (ICSTW) (2017): 87-96

Regular expressions (regexes) permit to describe set of strings using a pattern-based syntax. Writing a correct regex that exactly captures the desired set of strings is difficult, also because a regex is seldom syntactically incorrect, and so it is rare to detect faults at parse time. We propose a fault-based approach for generating tests for regexes. We identify fault classes representing possible mistakes a user can make when writing a regex, and we introduce the notion of *distinguishing string*, i.e., a string that is able to witness a fault. Then, we provide a tool, based on the automata representation of regexes, for generating distinguishing strings exposing the faults introduced in mutated versions of a regex under test. The basic generation process is improved by two techniques, namely *monitoring* and *collecting*. Experiments show that the approach produces compact test suites having a guaranteed fault detection capability, differently from other test generation approaches.

[download the pdf file] [DOI] [This paper won the **best paper award**. The tool is available at]

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