add method for Tree

hutool-core/src/test/java/cn/hutool/core/lang/tree/TreeTest.java

@@ -76,4 +76,48 @@ public class TreeTest {
 
 		Assert .assertEquals(7, ids.size());
 	}
+
+	@Test
+	public void cloneTreeTest(){
+		final Tree<String> tree = TreeUtil.buildSingle(nodeList, "0");
+		final Tree<String> cloneTree = tree.cloneTree();
+
+		List<String> ids = new ArrayList<>();
+		cloneTree.walk((tr)-> ids.add(tr.getId()));
+
+		Assert .assertEquals(7, ids.size());
+	}
+
+	@Test
+	public void filterTest(){
+		// 经过过滤，丢掉"用户添加"节点
+		final Tree<String> tree = TreeUtil.buildSingle(nodeList, "0");
+		tree.filter((t)->{
+			final CharSequence name = t.getName();
+			return null != name && name.toString().contains("管理");
+		});
+
+		List<String> ids = new ArrayList<>();
+		tree.walk((tr)-> ids.add(tr.getId()));
+		Assert .assertEquals(6, ids.size());
+	}
+
+	@Test
+	public void filterNewTest(){
+		final Tree<String> tree = TreeUtil.buildSingle(nodeList, "0");
+
+		// 经过过滤，生成新的树
+		Tree<String> newTree = tree.filterNew((t)->{
+			final CharSequence name = t.getName();
+			return null != name && name.toString().contains("管理");
+		});
+
+		List<String> ids = new ArrayList<>();
+		newTree.walk((tr)-> ids.add(tr.getId()));
+		Assert .assertEquals(6, ids.size());
+
+		List<String> ids2 = new ArrayList<>();
+		tree.walk((tr)-> ids2.add(tr.getId()));
+		Assert .assertEquals(7, ids2.size());
+	}
 }