Merge pull request #13810 from press0/master

pr: add return types for assertion; test WrongVoucher vs GoodVoucher

algorithms-modules/algorithms-searching/src/main/java/com/baeldung/algorithms/dfs/Graph.java

@@ -23,7 +23,7 @@ public class Graph {
         adjVertices.get(src).add(dest);
     }
 
-    public void dfsWithoutRecursion(int start) {
+    public boolean[] dfsWithoutRecursion(int start) {
         Stack<Integer> stack = new Stack<Integer>();
         boolean[] isVisited = new boolean[adjVertices.size()];
         stack.push(start);
@@ -38,20 +38,22 @@ public class Graph {
                 }
             }
         }
+        return isVisited;
     }
 
-    public void dfs(int start) {
+    public boolean[] dfs(int start) {
         boolean[] isVisited = new boolean[adjVertices.size()];
-        dfsRecursive(start, isVisited);
+        return dfsRecursive(start, isVisited);
     }
 
-    private void dfsRecursive(int current, boolean[] isVisited) {
+    private boolean[] dfsRecursive(int current, boolean[] isVisited) {
         isVisited[current] = true;
         visit(current);
         for (int dest : adjVertices.get(current)) {
             if (!isVisited[dest])
                 dfsRecursive(dest, isVisited);
         }
+        return isVisited;
     }
 
     public List<Integer> topologicalSort(int start) {

algorithms-modules/algorithms-searching/src/test/java/com/baeldung/algorithms/dfs/GraphUnitTest.java

@@ -1,7 +1,9 @@
 package com.baeldung.algorithms.dfs;
 
+import java.util.Arrays;
 import java.util.List;
 
+import org.junit.Assert;
 import org.junit.jupiter.api.Test;
 
 class GraphUnitTest {
@@ -9,9 +11,12 @@ class GraphUnitTest {
     @Test
     void givenDirectedGraph_whenDFS_thenPrintAllValues() {
         Graph graph = createDirectedGraph();
-        graph.dfs(0);
-        System.out.println();
-        graph.dfsWithoutRecursion(0);
+        boolean[] visited;
+        visited = graph.dfs(0);
+        boolean[] expected = new boolean[]{true, true, true, true, true, true};
+        Assert.assertArrayEquals(expected, visited);
+        visited = graph.dfsWithoutRecursion(0);
+        Assert.assertArrayEquals(expected, visited);
     }
 
     @Test
@@ -19,6 +24,8 @@ class GraphUnitTest {
         Graph graph = createDirectedGraph();
         List<Integer> list = graph.topologicalSort(0);
         System.out.println(list);
+        List<Integer> expected = Arrays.asList(0, 2, 1, 3, 4, 5);
+        Assert.assertEquals(expected, list);
     }
 
     private Graph createDirectedGraph() {