1 files changed, 69 insertions, 0 deletions
diff --git a/spec/lib/gitlab/background_migration/backfill_design_internal_ids_spec.rb b/spec/lib/gitlab/background_migration/backfill_design_internal_ids_spec.rb
new file mode 100644
index 00000000000..4bf59a02a31
--- /dev/null
+++ b/spec/lib/gitlab/background_migration/backfill_design_internal_ids_spec.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::BackgroundMigration::BackfillDesignInternalIds, :migration, schema: 20201030203854 do
+  subject { described_class.new(designs) }
+
+  let_it_be(:namespaces)     { table(:namespaces) }
+  let_it_be(:projects)       { table(:projects) }
+  let_it_be(:designs)        { table(:design_management_designs) }
+
+  let(:namespace) { namespaces.create!(name: 'foo', path: 'foo') }
+  let(:project) { projects.create!(namespace_id: namespace.id) }
+  let(:project_2) { projects.create!(namespace_id: namespace.id) }
+
+  def create_design!(proj = project)
+    designs.create!(project_id: proj.id, filename: generate(:filename))
+  end
+
+  def migrate!
+    relation = designs.where(project_id: [project.id, project_2.id]).select(:project_id).distinct
+
+    subject.perform(relation)
+  end
+
+  it 'backfills the iid for designs' do
+    3.times { create_design! }
+
+    expect do
+      migrate!
+    end.to change { designs.pluck(:iid) }.from(contain_exactly(nil, nil, nil)).to(contain_exactly(1, 2, 3))
+  end
+
+  it 'scopes IIDs and handles range and starting-point correctly' do
+    create_design!.update!(iid: 10)
+    create_design!.update!(iid: 12)
+    create_design!(project_2).update!(iid: 7)
+    project_3 = projects.create!(namespace_id: namespace.id)
+
+    2.times { create_design! }
+    2.times { create_design!(project_2) }
+    2.times { create_design!(project_3) }
+
+    migrate!
+
+    expect(designs.where(project_id: project.id).pluck(:iid)).to contain_exactly(10, 12, 13, 14)
+    expect(designs.where(project_id: project_2.id).pluck(:iid)).to contain_exactly(7, 8, 9)
+    expect(designs.where(project_id: project_3.id).pluck(:iid)).to contain_exactly(nil, nil)
+  end
+
+  it 'updates the internal ID records' do
+    design = create_design!
+    2.times { create_design! }
+    design.update!(iid: 10)
+    scope = { project_id: project.id }
+    usage = :design_management_designs
+    init = ->(_d, _s) { 0 }
+
+    ::InternalId.track_greatest(design, scope, usage, 10, init)
+
+    migrate!
+
+    next_iid = ::InternalId.generate_next(design, scope, usage, init)
+
+    expect(designs.pluck(:iid)).to contain_exactly(10, 11, 12)
+    expect(design.reload.iid).to eq(10)
+    expect(next_iid).to eq(13)
+  end
+end