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A collection of equivalence oracles
/* Copyright (C) 2013-2020 TU Dortmund
* This file is part of LearnLib, http://www.learnlib.de/.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package de.learnlib.oracle.equivalence;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Random;
import java.util.stream.Stream;
import de.learnlib.api.oracle.EquivalenceOracle.DFAEquivalenceOracle;
import de.learnlib.api.oracle.EquivalenceOracle.MealyEquivalenceOracle;
import de.learnlib.api.oracle.MembershipOracle;
import de.learnlib.api.oracle.MembershipOracle.DFAMembershipOracle;
import de.learnlib.api.oracle.MembershipOracle.MealyMembershipOracle;
import de.learnlib.buildtool.refinement.annotation.GenerateRefinement;
import de.learnlib.buildtool.refinement.annotation.Generic;
import de.learnlib.buildtool.refinement.annotation.Interface;
import de.learnlib.buildtool.refinement.annotation.Map;
import net.automatalib.automata.UniversalDeterministicAutomaton;
import net.automatalib.automata.concepts.Output;
import net.automatalib.automata.fsa.DFA;
import net.automatalib.automata.transducers.MealyMachine;
import net.automatalib.commons.util.mappings.MutableMapping;
import net.automatalib.util.automata.Automata;
import net.automatalib.util.automata.cover.Covers;
import net.automatalib.words.Word;
import net.automatalib.words.WordBuilder;
/**
* Implements an equivalence test by applying the Wp-method test on the given hypothesis automaton, as described in
* "Test Selection Based on Finite State Models" by S. Fujiwara et al. Instead of enumerating the test suite in order,
* this is a sampling implementation:
*
* - 1. sample uniformly from the states for a prefix
* - 2. sample geometrically a random word
* - 3. sample a word from the set of suffixes / state identifiers
*
* There are two parameters:minimalSize determines the minimal size of the random word, this is useful when one first
* performs a W(p)-method with some depth and continue with this randomized tester from that depth onward. The second
* parameter rndLength determines the expected length of the random word. (The expected length in effect is minimalSize
* + rndLength.) In the unbounded case it will not terminate for a correct hypothesis.
*
* @param
* automaton type
* @param
* input symbol type
* @param
* output domain type
*
* @author Joshua Moerman
*/
@GenerateRefinement(name = "DFARandomWpMethodEQOracle",
generics = "I",
parentGenerics = {@Generic(clazz = DFA.class, generics = {"?", "I"}),
@Generic("I"),
@Generic(clazz = Boolean.class)},
parameterMapping = @Map(from = MembershipOracle.class,
to = DFAMembershipOracle.class,
withGenerics = "I"),
interfaces = @Interface(clazz = DFAEquivalenceOracle.class, generics = "I"))
@GenerateRefinement(name = "MealyRandomWpMethodEQOracle",
generics = {"I", "O"},
parentGenerics = {@Generic(clazz = MealyMachine.class, generics = {"?", "I", "?", "O"}),
@Generic("I"),
@Generic(clazz = Word.class, generics = "O")},
parameterMapping = @Map(from = MembershipOracle.class,
to = MealyMembershipOracle.class,
withGenerics = {"I", "O"}),
interfaces = @Interface(clazz = MealyEquivalenceOracle.class, generics = {"I", "O"}))
public class RandomWpMethodEQOracle & Output, I, D>
extends AbstractTestWordEQOracle {
private final int minimalSize;
private final int rndLength;
private final int bound;
private final Random rand;
/**
* Constructor for an unbounded testing oracle.
*
* @param sulOracle
* oracle which answers tests.
* @param minimalSize
* minimal size of the random word
* @param rndLength
* expected length (in addition to minimalSize) of random word
*/
public RandomWpMethodEQOracle(MembershipOracle sulOracle, int minimalSize, int rndLength) {
this(sulOracle, minimalSize, rndLength, 0);
}
/**
* Constructor for a bounded testing oracle.
*
* @param sulOracle
* oracle which answers tests.
* @param minimalSize
* minimal size of the random word
* @param rndLength
* expected length (in addition to minimalSize) of random word
* @param bound
* specifies the bound (set to 0 for unbounded).
*/
public RandomWpMethodEQOracle(MembershipOracle sulOracle, int minimalSize, int rndLength, int bound) {
this(sulOracle, minimalSize, rndLength, bound, 1);
}
/**
* Constructor for a bounded testing oracle with specific batch size.
*
* @param sulOracle
* oracle which answers tests.
* @param minimalSize
* minimal size of the random word
* @param rndLength
* expected length (in addition to minimalSize) of random word
* @param bound
* specifies the bound (set to 0 for unbounded).
* @param batchSize
* size of the batches sent to the membership oracle
*/
public RandomWpMethodEQOracle(MembershipOracle sulOracle,
int minimalSize,
int rndLength,
int bound,
int batchSize) {
this(sulOracle, minimalSize, rndLength, bound, new Random(), batchSize);
}
/**
* Constructor for a bounded testing oracle with specific batch size.
*
* @param sulOracle
* oracle which answers tests.
* @param minimalSize
* minimal size of the random word
* @param rndLength
* expected length (in addition to minimalSize) of random word
* @param bound
* specifies the bound (set to 0 for unbounded).
* @param random
* custom Random generator.
* @param batchSize
* size of the batches sent to the membership oracle
*/
public RandomWpMethodEQOracle(MembershipOracle sulOracle,
int minimalSize,
int rndLength,
int bound,
Random random,
int batchSize) {
super(sulOracle, batchSize);
this.minimalSize = minimalSize;
this.rndLength = rndLength;
this.bound = bound;
this.rand = random;
}
@Override
protected Stream> generateTestWords(A hypothesis, Collection inputs) {
UniversalDeterministicAutomaton aut = hypothesis;
return doGenerateTestWords(aut, inputs);
}
private Stream> doGenerateTestWords(UniversalDeterministicAutomaton hypothesis,
Collection inputs) {
// Note that we want to use ArrayLists because we want constant time random access
// We will sample from this for a prefix
List> stateCover = new ArrayList<>(hypothesis.size());
Covers.stateCover(hypothesis, inputs, stateCover);
// Then repeatedly from this for a random word
List arrayAlphabet = new ArrayList<>(inputs);
// Finally we test the state with a suffix, sometimes a global one, sometimes local
List> globalSuffixes = new ArrayList<>();
Automata.characterizingSet(hypothesis, inputs, globalSuffixes);
MutableMapping>> localSuffixSets = hypothesis.createStaticStateMapping();
for (S state : hypothesis.getStates()) {
List> suffixSet = new ArrayList<>();
Automata.stateCharacterizingSet(hypothesis, inputs, state, suffixSet);
localSuffixSets.put(state, suffixSet);
}
final Stream> result = Stream.generate(() -> generateSingleTestWord(hypothesis,
stateCover,
arrayAlphabet,
globalSuffixes,
localSuffixSets));
return bound > 0 ? result.limit(bound) : result;
}
private Word generateSingleTestWord(UniversalDeterministicAutomaton hypothesis,
List> stateCover,
List arrayAlphabet,
List> globalSuffixes,
MutableMapping>> localSuffixSets) {
WordBuilder wb = new WordBuilder<>(minimalSize + rndLength + 1);
// pick a random state
wb.append(stateCover.get(rand.nextInt(stateCover.size())));
// construct random middle part (of some expected length)
int size = minimalSize;
while ((size > 0) || (rand.nextDouble() > 1 / (rndLength + 1.0))) {
wb.append(arrayAlphabet.get(rand.nextInt(arrayAlphabet.size())));
if (size > 0) {
size--;
}
}
// pick a random suffix for this state
// 50% chance for state testing, 50% chance for transition testing
if (rand.nextBoolean()) {
// global
if (!globalSuffixes.isEmpty()) {
wb.append(globalSuffixes.get(rand.nextInt(globalSuffixes.size())));
}
} else {
// local
S state2 = hypothesis.getState(wb);
List> localSuffixes = localSuffixSets.get(state2);
if (!localSuffixes.isEmpty()) {
wb.append(localSuffixes.get(rand.nextInt(localSuffixes.size())));
}
}
return wb.toWord();
}
}