Make DFS and BFS search algorithms generic (fixes #4229) (#4230)

src/test/java/com/thealgorithms/searches/DepthFirstSearchTest.java

@@ -0,0 +1,91 @@
+package com.thealgorithms.searches;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.thealgorithms.datastructures.Node;
+import java.util.List;
+import java.util.Optional;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class DepthFirstSearchTest {
+
+    private Node<Integer> root;
+    private DepthFirstSearch<Integer> dfs;
+
+    //
+    // Tree structure:
+    //          1
+    //        / | \
+    //       2  3  4
+    //      / \
+    //     5   6
+
+    @BeforeEach
+    public void setUp() {
+        // nodes declaration
+        root = new Node<>(1);
+
+        var nodeB = new Node<>(2);
+        var nodeC = new Node<>(3);
+        var nodeD = new Node<>(4);
+
+        var nodeE = new Node<>(5);
+        var nodeF = new Node<>(6);
+
+        // tree initialization
+        root.addChild(nodeB);
+        root.addChild(nodeC);
+        root.addChild(nodeD);
+
+        nodeB.addChild(nodeE);
+        nodeB.addChild(nodeF);
+
+        // create an instance to monitor the visited nodes
+        dfs = new DepthFirstSearch<>();
+    }
+
+    @Test
+    public void testSearchRoot() {
+        Integer expectedValue = 1;
+        List<Integer> expectedPath = List.of(1);
+
+        // check value
+        Optional<Node<Integer>> value = dfs.recursiveSearch(root, expectedValue);
+        assertEquals(expectedValue, value.orElse(new Node<>(null)).getValue());
+
+        // check path
+        assertArrayEquals(expectedPath.toArray(), dfs.getVisited().toArray());
+    }
+
+    @Test
+    public void testSearch4() {
+        Integer expectedValue = 4;
+        List<Integer> expectedPath = List.of(1, 2, 5, 6, 3, 4);
+
+        // check value
+        Optional<Node<Integer>> value = dfs.recursiveSearch(root, expectedValue);
+        assertEquals(expectedValue, value.orElse(new Node<>(null)).getValue());
+
+        // check path
+        assertArrayEquals(expectedPath.toArray(), dfs.getVisited().toArray());
+    }
+
+    @Test
+    void testNullRoot() {
+        var value = dfs.recursiveSearch(null, 4);
+        assertTrue(value.isEmpty());
+    }
+
+    @Test
+    void testSearchValueThatNotExists() {
+        List<Integer> expectedPath = List.of(1, 2, 5, 6, 3, 4);
+        var value = dfs.recursiveSearch(root, 10);
+
+        // check that the value is empty because it's not exists in the tree
+        assertTrue(value.isEmpty());
+
+        // check path is the whole list
+        assertArrayEquals(expectedPath.toArray(), dfs.getVisited().toArray());
+    }
+}