add test case for NL* bug

algorithms/active/nlstar/pom.xml

@@ -70,6 +70,11 @@ limitations under the License.
             <groupId>de.learnlib.testsupport</groupId>
             <artifactId>learnlib-learner-it-support</artifactId>
         </dependency>
+        <dependency>
+            <groupId>de.learnlib</groupId>
+            <artifactId>learnlib-equivalence-oracles</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>de.learnlib</groupId>
             <artifactId>learnlib-membership-oracles</artifactId>

algorithms/active/nlstar/src/test/java/de/learnlib/algorithms/nlstar/NLStarTest.java

@@ -0,0 +1,73 @@
+/* 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.algorithms.nlstar;
+
+import de.learnlib.oracle.equivalence.SampleSetEQOracle;
+import de.learnlib.oracle.membership.SimulatorOracle;
+import de.learnlib.util.Experiment;
+import net.automatalib.automata.fsa.NFA;
+import net.automatalib.automata.fsa.impl.compact.CompactNFA;
+import net.automatalib.util.automata.Automata;
+import net.automatalib.util.automata.builders.AutomatonBuilders;
+import net.automatalib.util.automata.fsa.NFAs;
+import net.automatalib.words.Alphabet;
+import net.automatalib.words.Word;
+import net.automatalib.words.impl.Alphabets;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+public class NLStarTest {
+
+    /**
+     * Test case for the bug described in issue <a href="https://github.com/LearnLib/learnlib/issues/70">#70</a>.
+     */
+    @Test
+    public void testIssue70() {
+        final Alphabet<Character> alphabet = Alphabets.characters('a', 'b');
+
+        // @formatter:off
+        final CompactNFA<Character> nfa = AutomatonBuilders.newNFA(alphabet)
+                                                           .withInitial("q0")
+                                                           .from("q0")
+                                                                .on('a').to("q1")
+                                                                .on('b').to("q2")
+                                                           .from("q1").on('b').to("q1")
+                                                           .from("q2").on('a').to("q2")
+                                                           .withAccepting("q1", "q2")
+                                                           .create();
+        // @formatter:on
+
+        final SimulatorOracle<Character, Boolean> mqOracle = new SimulatorOracle<>(nfa);
+
+        final SampleSetEQOracle<Character, Boolean> eqOracle = new SampleSetEQOracle<>(false);
+        eqOracle.addAll(mqOracle,
+                        Word.fromCharSequence("a"),
+                        Word.fromCharSequence("ab"),
+                        Word.fromCharSequence("aa"),
+                        Word.fromCharSequence("bab"));
+
+        final NLStarLearner<Character> learner = new NLStarLearner<>(alphabet, mqOracle);
+
+        final Experiment<NFA<?, Character>> experiment = new Experiment<>(learner, eqOracle, alphabet);
+        experiment.run();
+        final NFA<?, Character> hyp = experiment.getFinalHypothesis();
+
+        Assert.assertEquals(nfa.size(), hyp.size());
+        Assert.assertTrue(Automata.testEquivalence(NFAs.determinize(nfa, false, false),
+                                                   NFAs.determinize(hyp, alphabet, false, false),
+                                                   alphabet));
+    }
+}

algorithms/active/nlstar/src/test/java/de/learnlib/algorithms/nlstar/NLStarIT.java → algorithms/active/nlstar/src/test/java/de/learnlib/algorithms/nlstar/it/NLStarIT.java

@@ -13,8 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package de.learnlib.algorithms.nlstar;
+package de.learnlib.algorithms.nlstar.it;
 
+import de.learnlib.algorithms.nlstar.NLStarLearner;
 import de.learnlib.api.oracle.MembershipOracle.DFAMembershipOracle;
 import de.learnlib.testsupport.it.learner.AbstractDFALearnerIT;
 import de.learnlib.testsupport.it.learner.LearnerVariantList.DFALearnerVariantList;