FIX: tweak restorer spec to make it stableish (#8300)

spec/lib/backup_restore/restorer_spec.rb

@@ -3,7 +3,7 @@
 require 'rails_helper'
 
 # Causes flakiness
-xdescribe BackupRestore::Restorer do
+describe BackupRestore::Restorer do
   it 'detects which pg_dump output is restorable to different schemas' do
     {
       "9.6.7" => true,
@@ -106,22 +106,21 @@ xdescribe BackupRestore::Restorer do
     let!(:admin) { Fabricate(:admin) }
     before do
       SiteSetting.allow_restore = true
-      @restore_path = File.join(Rails.root, 'public', 'backups', RailsMultisite::ConnectionManagement.current_db)
       described_class.any_instance.stubs(ensure_we_have_a_filename: true)
       described_class.any_instance.stubs(initialize_state: true)
     end
+
     after do
-      ActiveRecord::Base.clear_all_connections!
-      Rails.configuration.multisite = false
-      RailsMultisite::ConnectionManagement.clear_settings!
-      ActiveRecord::Base.establish_connection
+      SiteSetting.allow_restore = false
+      described_class.any_instance.unstub(:ensure_we_have_a_filename)
+      described_class.any_instance.unstub(:initialize_state)
     end
+
     let(:conn) { RailsMultisite::ConnectionManagement }
     let(:restorer) { described_class.new(admin.id) }
 
-    it 'correctly reconnects to database' do
+    it 'correctly reconnects to database', type: :multisite do
       restorer.instance_variable_set(:@current_db, 'second')
-      conn.config_filename = "spec/fixtures/multisite/two_dbs.yml"
       conn.establish_connection(db: 'second')
       expect(RailsMultisite::ConnectionManagement.current_db).to eq('second')
       ActiveRecord::Base.connection_pool.spec.config[:db_key] = "incorrect_db"
@@ -129,7 +128,7 @@ xdescribe BackupRestore::Restorer do
       expect(RailsMultisite::ConnectionManagement.current_db).to eq('second')
     end
 
-    it 'it is not erroring for non multisite' do
+    it 'it is not erroring for non multisite', type: :multisite do
       RailsMultisite::ConnectionManagement::clear_settings!
       expect { restorer.send(:reconnect_database) }.not_to raise_error
     end