add RedBlackTree#include?

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Alias `RedBlackTree#left_most_node` as `RedBlackTree#min`
 - Add `RedBlackTree#search`
+- Add `RedBlackTree#include?`
 
 ## [0.1.1] - 2024-08-04
 

lib/red-black-tree.rb

@@ -229,6 +229,13 @@ def search data
     _search data, @root
   end
 
+  # Returns true if there is a node which matches the given data/value, and false if there is not.
+  #
+  # @return [true, false]
+  def include? data
+    !!search(data)
+  end
+
   private
 
   # Rotates a (sub-)tree starting from the given node in the given direction.

test/test_red_black_tree.rb

@@ -709,6 +709,38 @@ def test_sub_tree_search
     end
   end
 
+  class TestInclude < Minitest::Test
+    def test_new_tree_include
+      tree = RedBlackTree.new
+      refute tree.include? 10
+    end
+
+    def test_single_node_tree_include
+      tree = RedBlackTree.new
+      node_10 = RedBlackTree::IntegerNode.new 10
+      tree << node_10
+      assert tree.include? 10
+    end
+
+    def test_sub_tree_include
+      tree = RedBlackTree.new
+      node_10 = RedBlackTree::IntegerNode.new 10
+      tree << node_10
+      node_5 = RedBlackTree::IntegerNode.new 5
+      tree << node_5
+      node_15 = RedBlackTree::IntegerNode.new 15
+      tree << node_15
+      node_1 = RedBlackTree::IntegerNode.new 1
+      tree << node_1
+      node_4 = RedBlackTree::IntegerNode.new 4
+      tree << node_4
+      assert tree.include? 5
+      assert tree.include? 15
+      tree.delete! node_5
+      refute tree.include? 5
+    end
+  end
+
   class TestShift < Minitest::Test
     def test_new_tree_shift
       tree = RedBlackTree.new