adding tests for BKTree

src/test/java/picard/util/BKTreeTest.java

+package picard.util;
+
+import org.testng.Assert;
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+
+import java.util.*;
+
+import static org.testng.Assert.*;
+
+public class BKTreeTest {
+
+    @DataProvider(name = "testQueryDataProvider")
+    public Object[][] testQueryDataProvider() {
+        final Set<String> dictionary = new HashSet<>(Arrays.asList("ACGCA","GCTCG","GGCTA","CGTCG","AGTCG","GGTCG","AACCT"));
+        final BKTree<String> tree = new BKTree<>((s1, s2) -> StringDistanceUtils.countMismatches(new byte[][]{s1.getBytes()}, new byte[][]{s2.getBytes()}, null, 0));
+        for (final String word : dictionary) {
+            tree.insert(word);
+        }
+        final List<Object[]> tests = new ArrayList<>();
+        for (final String query : dictionary) {
+            final Map<Integer, Set<String>> expectedResult= new HashMap<>();
+            expectedResult.put(0, new HashSet<>(Collections.singletonList(query)));
+            tests.add(new Object[]{query, 0, tree, new HashMap<>(expectedResult)});
+            if (query.equals("GCTCG")) {
+                expectedResult.put(1, new HashSet<>(Collections.singletonList("GGTCG")));
+            } else if (query.equals("CGTCG")) {
+                expectedResult.put(1, new HashSet<>(Arrays.asList("AGTCG", "GGTCG")));
+            } else if (query.equals("AGTCG")) {
+                expectedResult.put(1, new HashSet<>(Arrays.asList("CGTCG", "GGTCG")));
+            } else if (query.equals("GGTCG")) {
+                expectedResult.put(1, new HashSet<>(Arrays.asList("CGTCG", "AGTCG", "GCTCG")));
+            }
+            tests.add(new Object[]{query, 1, tree, new HashMap<>(expectedResult)});
+        }
+        return tests.toArray(new Object[][]{});
+    }
+    @Test(dataProvider = "testQueryDataProvider")
+    public void testQuery(final String query, final int maxDist, final BKTree<String> tree, final Map<Integer, Set<String>> expectedResult) {
+        final Map<Integer, LinkedList<String>> results = tree.query(query, maxDist);
+        Assert.assertEquals(results.size(), expectedResult.size());
+        for (final Map.Entry<Integer, LinkedList<String>> matchSet : results.entrySet()) {
+            Assert.assertEquals(matchSet.getValue().size(), expectedResult.get(matchSet.getKey()).size());
+            Assert.assertTrue(expectedResult.get(matchSet.getKey()).containsAll(matchSet.getValue()));
+        }
+    }
+}
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