fixes: #1280 and test: added tests for DFS algorithm (#1303)

* fix: fixed error in DepthFirstSearch algorithm and test: added tests for DepthFirstSearch algorithm.

* changed traverseDFS function parameters in DepthFirstSearch.js file

Trees/test/DepthFirstSearch.test.js

@@ -0,0 +1,46 @@
+import { searchDFS, traverseDFS } from '../DepthFirstSearch'
+
+describe('Depth First Tree Traversal', () => {
+  const tree = [
+    { value: 6, left: 1, right: 2 },
+    { value: 5, left: 3, right: 4 },
+    { value: 7, left: null, right: 5 },
+    { value: 3, left: 6, right: null },
+    { value: 4, left: null, right: null },
+    { value: 9, left: 7, right: 8 },
+    { value: 2, left: 9, right: null },
+    { value: 8, left: null, right: null },
+    { value: 10, left: null, right: null },
+    { value: 1, left: null, right: null }
+  ]
+
+  //            6
+  //           / \
+  //          5   7
+  //         / \   \
+  //        3   4   9
+  //       /       / \
+  //      2       8   10
+  //     /
+  //    1
+
+  it('should be null if given value is not present in the tree - DF Search', () => {
+    const res = searchDFS(tree, 200)
+    expect(res).toStrictEqual(null)
+  })
+
+  it('should return the node if given value is present in the tree - DF Search', () => {
+    const res = searchDFS(tree, 9)
+    expect(res).toStrictEqual({ value: 9, left: 7, right: 8 })
+  })
+
+  it('should return empty array if given root is not present in the tree - DF Traversal', () => {
+    const traversal = traverseDFS(tree, 200)
+    expect(traversal).toStrictEqual([])
+  })
+
+  it('should return DFT array of given tree from specified root if given root is present in the tree - DF Traversal', () => {
+    const traversal = traverseDFS(tree, 6)
+    expect(traversal).toStrictEqual([1, 2, 3, 4, 5, 8, 10, 9, 7, 6])
+  })
+})