Migrate root_id column on Namespaces table62214-namespace-database-migration

Includes:
- Migration to add root_id column on Namespaces table
- Background migration to schedule the population of this new field

2 files changed, 77 insertions, 1 deletions

diff --git a/spec/db/schema_spec.rb b/spec/db/schema_spec.rb
index 6cfec5f4017..55b42dbe35f 100644
--- a/spec/db/schema_spec.rb
+++ b/spec/db/schema_spec.rb
@@ -46,7 +46,7 @@ describe 'Database schema' do
     ldap_group_links: %w[group_id],
     members: %w[source_id created_by_id],
     merge_requests: %w[last_edited_by_id state_id],
-    namespaces: %w[owner_id parent_id],
+    namespaces: %w[owner_id parent_id root_id],
     notes: %w[author_id commit_id noteable_id updated_by_id resolved_by_id discussion_id],
     notification_settings: %w[source_id],
     oauth_access_grants: %w[resource_owner_id application_id],
diff --git a/spec/lib/gitlab/background_migration/populate_namespace_root_id_column_spec.rb b/spec/lib/gitlab/background_migration/populate_namespace_root_id_column_spec.rb
new file mode 100644
index 00000000000..57e926b7c55
--- /dev/null
+++ b/spec/lib/gitlab/background_migration/populate_namespace_root_id_column_spec.rb
@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe Gitlab::BackgroundMigration::PopulateNamespaceRootIdColumn, :migration, schema: 20190617181054 do
+  let(:namespaces_table) { table(:namespaces) }
+
+  def create_namespace_for(parent:, iid:)
+    namespaces_table.create!(
+      name: "#{parent.name}-group_#{iid}",
+      path: "#{parent.name}-group_#{iid}",
+      parent_id: parent.id
+    )
+  end
+
+  describe '#perform' do
+    let(:root_namespace_a) { namespaces_table.create!(name: 'root_a', path: 'root-a') }
+    let(:root_namespace_b) { namespaces_table.create!(name: 'root_b', path: 'root-b') }
+
+    before do
+      (1..10).each do |subgroup_id|
+        create_namespace_for(parent: root_namespace_a, iid: subgroup_id)
+        create_namespace_for(parent: root_namespace_b, iid: subgroup_id)
+      end
+    end
+
+    it 'updates the root id of root namespaces' do
+      subject.perform(root_namespace_a.id, root_namespace_b.id)
+
+      expect(root_namespace_a.reload.root_id).to eq(root_namespace_a.id)
+      expect(root_namespace_b.reload.root_id).to eq(root_namespace_b.id)
+    end
+
+    it 'updates the root id of all namespaces' do
+      subject.perform(root_namespace_a.id, root_namespace_b.id)
+
+      namespace_a_children = namespaces_table.where(parent_id: root_namespace_a.id)
+      namespace_b_children = namespaces_table.where(parent_id: root_namespace_b.id)
+
+      namespace_a_children.each do |group|
+        expect(group.root_id).to eq(root_namespace_a.id)
+      end
+
+      namespace_b_children.each do |group|
+        expect(group.root_id).to eq(root_namespace_b.id)
+      end
+    end
+
+    context 'when a subgroup has children' do
+      let(:subgroup) do
+        create_namespace_for(
+          parent: root_namespace_a,
+          iid: 50
+        )
+      end
+
+      before do
+        (1..10).each do |subgroup_id|
+          create_namespace_for(parent: subgroup, iid: subgroup_id)
+        end
+      end
+
+      it 'updates inner groups' do
+        subject.perform(root_namespace_a.id, root_namespace_b.id)
+
+        subgroup_children = namespaces_table.where(parent_id: subgroup.id)
+
+        expect(subgroup.reload.root_id).to eq(root_namespace_a.id)
+
+        subgroup_children.each do |group|
+          expect(group.root_id).to eq(root_namespace_a.id)
+        end
+      end
+    end
+  end
+end