MiqAeNamespace should use ancestry instead of acts_as_tree

Fixes ManageIQ/manageiq-automation_engine#409

db/migrate/20200203200855_add_ancestry_to_miq_ae_namespace.rb

@@ -0,0 +1,40 @@
+class AddAncestryToMiqAeNamespace < ActiveRecord::Migration[5.0]
+  class MiqAeNamespace < ActiveRecord::Base
+    self.inheritance_column = :_type_disabled # disable STI
+  end
+
+  def update_ns_parent(parent)
+    ancestry = [parent.ancestry, parent.id].compact.join("/") if parent
+    MiqAeNamespace.where(:parent_id => parent.try(:id)).each do |ns|
+      ns.update(:ancestry => ancestry) if ancestry
+      update_ns_parent(ns)
+    end
+  end
+
+  def up
+    add_column :miq_ae_namespaces, :ancestry, :string
+    add_index :miq_ae_namespaces, :ancestry
+
+    say_with_time("Converting MiqAeNamespaces from parent_id to ancestry") do
+      update_ns_parent(nil)
+    end
+
+    remove_index :miq_ae_namespaces, :column => :parent_id
+    remove_column :miq_ae_namespaces, :parent_id
+  end
+
+  def down
+    add_column :miq_ae_namespaces, :parent_id, :bigint
+    add_index :miq_ae_namespaces, :parent_id
+
+    say_with_time("Converting MiqAeNamespaces from ancestry to parent_id") do
+      MiqAeNamespace.all.each do |ns|
+        parent_ns_id = ns.ancestry.split("/").last.to_i if ns.ancestry.present?
+        ns.update(:parent_id => parent_ns_id)
+      end
+    end
+
+    remove_index :miq_ae_namespaces, :column => :ancestry
+    remove_column :miq_ae_namespaces, :ancestry
+  end
+end

spec/migrations/20200203200855_add_ancestry_to_miq_ae_namespace_spec.rb

@@ -0,0 +1,54 @@
+require_migration
+
+describe AddAncestryToMiqAeNamespace do
+  let(:ns_stub) { migration_stub(:MiqAeNamespace) }
+
+  migration_context :up do
+    # nodes:
+    # ns1
+    #   ns11
+    #     ns111
+    #     ns112
+    # ns2
+    #   ns21 (created before parent)
+    it "updates tree" do
+      ns1   = ns_stub.create!
+      ns2   = ns_stub.create!
+      ns11  = ns_stub.create!(:parent_id => ns1.id)
+      ns111 = ns_stub.create!(:parent_id => ns11.id)
+      ns112 = ns_stub.create!(:parent_id => ns11.id)
+      ns21  = ns_stub.create!(:parent_id => ns2.id)
+
+      migrate
+
+      expect(ns1.reload.ancestry).to be_nil
+      expect(ns2.reload.ancestry).to be_nil
+
+      expect(ns11.reload.ancestry).to eq(ns1.id.to_s)
+      expect(ns111.reload.ancestry).to eq("#{ns1.id}/#{ns11.id}")
+      expect(ns112.reload.ancestry).to eq("#{ns1.id}/#{ns11.id}")
+      expect(ns21.reload.ancestry).to eq(ns2.id.to_s)
+    end
+  end
+
+  migration_context :down do
+    it "updates tree" do
+      ns1   = ns_stub.create!
+      ns2   = ns_stub.create!
+      ns11  = ns_stub.create!(:ancestry => ns1.id.to_s)
+      ns111 = ns_stub.create!(:ancestry => "#{ns1.id}/#{ns11.id}")
+      ns112 = ns_stub.create!(:ancestry => "#{ns1.id}/#{ns11.id}")
+      ns21  = ns_stub.create!(:ancestry => ns2.id.to_s)
+
+      migrate
+
+      expect(ns1.reload.parent_id).to eq(nil)
+      expect(ns2.reload.parent_id).to eq(nil)
+
+      expect(ns11.reload.parent_id).to eq(ns1.id)
+      expect(ns111.reload.parent_id).to eq(ns11.id)
+      expect(ns112.reload.parent_id).to eq(ns11.id)
+      expect(ns21.reload.parent_id).to eq(ns2.id)
+    end
+  end
+end