Fix Elastic::MigrationWorker current_migration

Changelog: fixed
EE: true

ee/app/workers/elastic/migration_worker.rb

@@ -87,9 +87,9 @@ module Elastic
     end
 
     def current_migration
-      completed_migrations = Elastic::MigrationRecord.load_versions(completed: true)
+      uncompleted_migrations = Elastic::MigrationRecord.load_versions(completed: false)
 
-      Elastic::DataMigrationService.migrations.find { |migration| !completed_migrations.include?(migration.version) }
+      Elastic::DataMigrationService.migrations.find { |migration| uncompleted_migrations.include?(migration.version) }
     end
 
     def pause_indexing!(migration)

ee/spec/workers/elastic/migration_worker_spec.rb

@@ -22,7 +22,10 @@ RSpec.describe Elastic::MigrationWorker, :elastic do
 
       before do
         stub_ee_application_setting(elasticsearch_indexing: true)
+      end
 
+      context 'an unexecuted migration present' do
+        before do
           allow(subject).to receive(:current_migration).and_return(migration)
         end
 
@@ -32,18 +35,6 @@ RSpec.describe Elastic::MigrationWorker, :elastic do
           expect { subject.perform }.to change { Gitlab::Elastic::Helper.default.migrations_index_exists? }.from(false).to(true)
         end
 
-      context 'no unexecuted migrations' do
-        before do
-          allow(subject).to receive(:current_migration).and_return(nil)
-        end
-
-        it 'skips execution' do
-          expect(subject).not_to receive(:execute_migration)
-
-          expect(subject.perform).to be_falsey
-        end
-      end
-
         context 'migration is halted' do
           using RSpec::Parameterized::TableSyntax
 
@@ -187,5 +178,30 @@ RSpec.describe Elastic::MigrationWorker, :elastic do
           end
         end
       end
+
+      context 'no unexecuted migrations' do
+        before do
+          allow(subject).to receive(:current_migration).and_return(nil)
+        end
+
+        it 'skips execution' do
+          expect(subject).not_to receive(:execute_migration)
+
+          expect(subject.perform).to be_falsey
+        end
+      end
+
+      context 'load_versions returns empty array' do
+        before do
+          allow(Elastic::MigrationRecord).to receive(:load_versions).and_return([])
+        end
+
+        it 'skips execution' do
+          expect(subject).not_to receive(:execute_migration)
+
+          expect(subject.perform).to be_falsey
+        end
+      end
+    end
   end
 end