fix moving outcomes via csv import

closes OUT-3426

flag = none

Test plan:
- save the sample data at the bottom of
  http://canvas.docker/doc/api/file.outcomes_csv.html
  to a csv file
- on the account outcomes page, import
  the file's outcomes into the account
- update the file with a second group
  d,group,Child group 2,child group description,G-1.2,,,active,a,
- update the outcome to belong to the new group
  c,outcome,...,active,d,3,...
- verify that update completes successfully
  and outcome has moved to theh newly
  created "Child group 2"

Change-Id: Ie8f26497bb58bf513b2fc6734be213601e2442b4
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/221207
Tested-by: Jenkins
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Frank Murphy <fmurphy@instructure.com>
QA-Review: Pat Renner <prenner@instructure.com>
Product-Review: Michael Brewer-Davis <mbd@instructure.com>

lib/outcomes/import.rb

@@ -273,15 +273,17 @@ module Outcomes
         where(workflow_state: 'deleted')
       resurrect.update_all(workflow_state: 'active')
 
+      # add new parents before removing old to avoid deleting last link
+      # to an aligned outcome
+      existing_parent_ids = existing_links.pluck(:associated_asset_id)
+      new_parents = parents.reject { |p| existing_parent_ids.include?(p.id) }
+      new_parents.each { |p| p.add_outcome(outcome) }
+
       kill = existing_links.
         where.not(associated_asset_id: next_parent_ids).
         where(associated_asset_type: 'LearningOutcomeGroup').
         where(workflow_state: 'active')
       kill.destroy_all
-
-      existing_parent_ids = existing_links.pluck(:associated_asset_id)
-      new_parents = parents.reject { |p| existing_parent_ids.include?(p.id) }
-      new_parents.each { |p| p.add_outcome(outcome) }
     end
 
     def outcome_import_id

spec/lib/outcomes/import_spec.rb

@@ -415,7 +415,15 @@ RSpec.describe Outcomes::Import do
       it 'reassigns parents of existing outcome' do
         parent1.add_outcome(existing_outcome)
         importer.import_outcome(**outcome_attributes, parent_guids: 'parent2')
-          expect(parent1.child_outcome_links.active.map(&:content)).to be_empty
+        expect(parent1.child_outcome_links.active.map(&:content)).to be_empty
+        expect(parent2.child_outcome_links.active.map(&:content)).to include existing_outcome
+      end
+
+      it 'reassigns parents of an aligned outcome' do
+        outcome_with_rubric(outcome: existing_outcome)
+        parent1.add_outcome(existing_outcome)
+        importer.import_outcome(**outcome_attributes, parent_guids: 'parent2')
+        expect(parent1.child_outcome_links.active.map(&:content)).to be_empty
         expect(parent2.child_outcome_links.active.map(&:content)).to include existing_outcome
       end