Add SplayTree (#5142)

src/test/java/com/thealgorithms/datastructures/trees/SplayTreeTest.java

@@ -0,0 +1,113 @@
+package com.thealgorithms.datastructures.trees;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+public class SplayTreeTest {
+
+    @ParameterizedTest
+    @MethodSource("traversalStrategies")
+    public void testTraversal(SplayTree.TreeTraversal traversal, List<Integer> expected) {
+        SplayTree tree = createComplexTree();
+        List<Integer> result = tree.traverse(traversal);
+        assertEquals(expected, result);
+    }
+
+    @ParameterizedTest
+    @MethodSource("valuesToTest")
+    public void testSearch(int value) {
+        SplayTree tree = createComplexTree();
+        assertTrue(tree.search(value));
+    }
+
+    @ParameterizedTest
+    @MethodSource("valuesToTest")
+    public void testDelete(int value) {
+        SplayTree tree = createComplexTree();
+        assertTrue(tree.search(value));
+        tree.delete(value);
+        assertFalse(tree.search(value));
+    }
+
+    @ParameterizedTest
+    @MethodSource("nonExistentValues")
+    public void testSearchNonExistent(int value) {
+        SplayTree tree = createComplexTree();
+        assertFalse(tree.search(value));
+    }
+
+    @ParameterizedTest
+    @MethodSource("nonExistentValues")
+    public void testDeleteNonExistent(int value) {
+        SplayTree tree = createComplexTree();
+        tree.delete(value);
+        assertFalse(tree.search(value));
+    }
+
+    @ParameterizedTest
+    @MethodSource("valuesToTest")
+    public void testDeleteThrowsExceptionForEmptyTree(int value) {
+        SplayTree tree = new SplayTree();
+        assertThrows(SplayTree.EmptyTreeException.class, () -> tree.delete(value));
+    }
+
+    @ParameterizedTest
+    @MethodSource("valuesToTest")
+    public void testInsertThrowsExceptionForDuplicateKeys(int value) {
+        SplayTree tree = createComplexTree();
+        assertThrows(SplayTree.DuplicateKeyException.class, () -> tree.insert(value));
+    }
+
+    @ParameterizedTest
+    @MethodSource("valuesToTest")
+    public void testSearchInEmptyTree(int value) {
+        SplayTree tree = new SplayTree();
+        assertFalse(tree.search(value));
+    }
+
+    private static Stream<Object[]> traversalStrategies() {
+        return Stream.of(new Object[] {SplayTree.IN_ORDER, Arrays.asList(5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90)}, new Object[] {SplayTree.PRE_ORDER, Arrays.asList(15, 5, 10, 80, 70, 45, 25, 20, 35, 30, 40, 55, 50, 65, 60, 75, 90, 85)},
+            new Object[] {SplayTree.POST_ORDER, Arrays.asList(10, 5, 20, 30, 40, 35, 25, 50, 60, 65, 55, 45, 75, 70, 85, 90, 80, 15)});
+    }
+
+    private static Stream<Integer> valuesToTest() {
+        return Stream.of(5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90);
+    }
+
+    private static Stream<Integer> nonExistentValues() {
+        return Stream.of(0, 100, 42, 58);
+    }
+
+    private SplayTree createComplexTree() {
+        SplayTree tree = new SplayTree();
+
+        tree.insert(50);
+        tree.insert(30);
+        tree.insert(40);
+        tree.insert(70);
+        tree.insert(60);
+        tree.insert(20);
+        tree.insert(80);
+        tree.insert(10);
+        tree.insert(25);
+        tree.insert(35);
+        tree.insert(45);
+        tree.insert(55);
+        tree.insert(65);
+        tree.insert(75);
+        tree.insert(85);
+        tree.insert(5);
+        tree.insert(90);
+        tree.insert(15);
+
+        return tree;
+    }
+}