Weapon regeX

With Weapon regeX you can mutate regular expressions which can be used in mutation testing. The generated regular expressions cover edge cases and typos. Weapon regeX is available for both Javascript and Scala. The Javascript version of the library is generated from Scala using ScalaJS.

The current supported versions for Scala are: 2.12.12 and 2.13.3.

Getting started

Scala

Add Weapon regeX to your build.sbt.

"io.stryker-mutator" %% "weapon-regex" % "0.3.0"

Mutate!

import weaponregex.WeaponRegeX
import scala.util.{Success, Failure}

WeaponRegeX.mutate("^abc(d+|[xyz])$") match {
  case Success(mutants) => mutants map (_.pattern) map println
  case Failure(e)       => print(e.getMessage)
}

Javascript

Install Weapon regeX with npm.

npm install weapon-regex

Mutate!

const wrx = require('weapon-regex');

let mutants = wrx.mutate("^abc(d+|[xyz])$");

mutants.forEach(mutant => {
  console.log(mutant.pattern);
});

API

Scala

The mutate function has the following signature:

//import scala.util.{Try, Success, Failure}

def mutate(
      pattern: String,
      mutators: Seq[TokenMutator] = BuiltinMutators.all,
      mutationLevels: Seq[Int] = null
  ): Try[Seq[Mutant]]

With the mutators argument you can give a select list of mutators that should be used in the mutation process. If omitted, all builtin mutators will be used. This list will be filtered depending on the mutationLevels argument.

A list of mutationLevels can also be passed to the function. The mutators will be filtered based on the levels in the list. If omitted, no filtering takes place.

This function will return a Success of of a sequence of Mutant if can be parsed, a Failure otherwise.

Javascript

The mutate function can be called with an options object to control which mutators should be used in the mutation process:

const wrx = require('weapon-regex');

let mutants = wrx.mutate("^abc(d+|[xyz])$",{
  mutators: Array.from(wrx.mutators.values()),
  mutationLevels: [1, 2, 3]
});

Both options can be omitted, and have the same functionality as the options described in the Scala API section. You can get a map of mutators from the mutators attribute of the library. It is a map from string (mutator name) to a mutator object.

This function will return a JavaScript Array of Mutant if can be parsed, or throw an exception otherwise.

Supported mutators

All the supported mutators and at which mutation level they appear are shown in the table below.

Boundary Mutators

BOLRemoval

It removes the beginning of line character "^"

Back to table 🔝

EOLRemoval

It removes the end of line character "$"

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BOL2BOI

It changes the beginning of line character "^" to a beginning of input character "\A"

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EOL2EOI

It changes the end of line character "^" to a end of input character "\z"

Back to table 🔝

Character class mutators

CharClassNegation

It flips the sign of a character class.

Back to table 🔝

CharClassChildRemoval

It removes a child of a character class.

Back to table 🔝

CharClassAnyChar

It changes a character class to a character class which matches any character.

Back to table 🔝

CharClassRangeModification

It changes the high and low of a range by one in both directions if possible.

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Predefined character class mutators

PredefCharClassNegation

It flips the sign of a predefined character class. All the predefined character classes are shown in the table below.

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PredefCharClassNullification

It removes the backslash from a predefined character class such as "\w".

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PredefCharClassAnyChar

It changes a predefined character class to a character class containing the predefined one and its negation.

Back to table 🔝

Quantifier mutators

QuantifierRemoval

It removes a quantifier. This is done for all possible quantifiers, even ranges, and the reluctant and possessive variants.

Back to table 🔝

QuantifierNChange

It changes the fixed amount quantifier to a couple range variants.

Back to table 🔝

QuantifierNOrMoreModification

It changes the n to infinity range quantifier to a couple variants where the low of the range is incremented an decremented by one.

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QuantifierNOrMoreChange

It turns an N or more range quantifier into a fixed number quantifier.

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QuantifierNMModification

It alters the N to M range quantifier by decrementing or incrementing the high and low of the range by one.

Back to table 🔝

QuantifierShortModification

It treats the shorthand quantifiers (?, *, +) as their corresponding range quantifier variant ({0,1}, {0,}, {1,}), and applies the same mutations as mentioned in the mutators above.

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QuantifierShortChange

It changes the shorthand quantifiers * and + to their fixed range quantifier variant.

Back to table 🔝

QuantifierReluctantAddition

It changes greedy quantifiers to reluctant quantifiers.

Back to table 🔝

Group mutators

GroupToNCGroup

It changes a normal group to a non-capturing group.

Back to table 🔝