From becbdcf3eb0cd702fe2ebb35ac0def31ea585fec Mon Sep 17 00:00:00 2001
From: Ryan O'Donnell <rodonnell@twitter.com>
Date: Wed, 10 May 2017 14:31:07 -0700
Subject: [PATCH] Add leaves instance method

---
 lib/ancestry/instance_methods.rb       |  6 ++++++
 test/concerns/tree_navigration_test.rb | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/lib/ancestry/instance_methods.rb b/lib/ancestry/instance_methods.rb
index a5529b32..365e2730 100644
--- a/lib/ancestry/instance_methods.rb
+++ b/lib/ancestry/instance_methods.rb
@@ -279,6 +279,12 @@ def subtree_ids depth_options = {}
       subtree(depth_options).pluck(self.ancestry_base_class.primary_key)
     end
 
+    # Leaves
+
+    def leaves
+      subtree.select{|node| node.childless? }
+    end
+
     # Callback disabling
 
     def without_ancestry_callbacks
diff --git a/test/concerns/tree_navigration_test.rb b/test/concerns/tree_navigration_test.rb
index 496663c6..a6e1ecee 100644
--- a/test/concerns/tree_navigration_test.rb
+++ b/test/concerns/tree_navigration_test.rb
@@ -35,6 +35,11 @@ def test_tree_navigation
         assert_equal descendants.map(&:id), lvl0_node.descendant_ids
         assert_equal descendants, lvl0_node.descendants
         assert_equal [lvl0_node] + descendants, lvl0_node.subtree
+        # Leaves assertions
+        leaves = lvl0_node.descendants.select do |node|
+          node.childless?
+        end
+        assert_equal lvl0_node.leaves, leaves
 
         lvl0_children.each do |lvl1_node, lvl1_children|
           # Ancestors assertions
@@ -68,6 +73,11 @@ def test_tree_navigation
           assert_equal descendants.map(&:id), lvl1_node.descendant_ids
           assert_equal descendants, lvl1_node.descendants
           assert_equal [lvl1_node] + descendants, lvl1_node.subtree
+          # Leaves assertions
+          leaves = lvl1_node.descendants.select do |node|
+            node.childless?
+          end
+          assert_equal lvl1_node.leaves, leaves
 
           lvl1_children.each do |lvl2_node, lvl2_children|
             # Ancestors assertions
@@ -101,6 +111,8 @@ def test_tree_navigation
             assert_equal descendants.map(&:id), lvl2_node.descendant_ids
             assert_equal descendants, lvl2_node.descendants
             assert_equal [lvl2_node] + descendants, lvl2_node.subtree
+            # Leaves assertions
+            assert_equal lvl2_node.leaves, [lvl2_node]
           end
         end
       end