fix: cast to char in child_ancestry_sql / rebuild_counter_cache

Before
======

We were casting to a fixed length char field. This can truncate parts of the path

After
=====

Using the conversion built into concat, so no need to CAST.

MySQL works best with CHAR
Postgresql works better with VARCHAR

lib/ancestry/materialized_path.rb

@@ -94,8 +94,8 @@ def ancestry_root
 
     def child_ancestry_sql
       %{
-        CASE WHEN #{table_name}.#{ancestry_column} IS NULL THEN CAST(#{table_name}.#{primary_key} AS CHAR)
-        ELSE      #{concat("#{table_name}.#{ancestry_column}", "'#{ancestry_delimiter}'", "CAST(#{table_name}.#{primary_key} AS CHAR)")}
+        CASE WHEN #{table_name}.#{ancestry_column} IS NULL THEN #{concat("#{table_name}.#{primary_key}")}
+        ELSE      #{concat("#{table_name}.#{ancestry_column}", "'#{ancestry_delimiter}'", "#{table_name}.#{primary_key}")}
         END
       }
     end

lib/ancestry/materialized_path2.rb

@@ -29,7 +29,7 @@ def ancestry_root
     end
 
     def child_ancestry_sql
-      concat("#{table_name}.#{ancestry_column}", "CAST(#{table_name}.#{primary_key} AS CHAR)", "'#{ancestry_delimiter}'")
+      concat("#{table_name}.#{ancestry_column}", "#{table_name}.#{primary_key}", "'#{ancestry_delimiter}'")
     end
 
     def ancestry_depth_sql

test/concerns/counter_cache_test.rb

@@ -88,16 +88,34 @@ def test_counter_cache_when_updating_record
   end
 
   def test_setting_counter_cache
-    AncestryTestDatabase.with_model :depth => 2, :width => 2, :counter_cache => true do |model, roots|
+    AncestryTestDatabase.with_model :depth => 3, :width => 2, :counter_cache => true do |model, roots|
+      # ensure they are successfully built
+      roots.each do |lvl0_node, lvl0_children|
+        assert_equal 2, lvl0_node.reload.children_count
+        lvl0_children.each do |lvl1_node, lvl1_children|
+          assert_equal 2, lvl1_node.reload.children_count
+          lvl1_children.each do |lvl2_node, _lvl2_children|
+            assert_equal 0, lvl2_node.reload.children_count
+          end
+        end
+      end
+
       model.update_all(model.counter_cache_column => 0)
       # ensure they are successfully broken
       roots.each do |lvl0_node, _lvl0_children|
         assert_equal 0, lvl0_node.reload.children_count
       end
       model.rebuild_counter_cache!
+
       # ensure they are successfully built
-      roots.each do |lvl0_node, _lvl0_children|
+      roots.each do |lvl0_node, lvl0_children|
         assert_equal 2, lvl0_node.reload.children_count
+        lvl0_children.each do |lvl1_node, lvl1_children|
+          assert_equal 2, lvl1_node.reload.children_count
+          lvl1_children.each do |lvl2_node, _lvl2_children|
+            assert_equal 0, lvl2_node.reload.children_count
+          end
+        end
       end
     end
   end