DEV: Less hacky way of rolling back DB changes

Some specs use psql to test database restores and dropping the table after the test needs to happen outside of rspec because of transactions. The previous attempt lead to some changes to be stored in the test database.

lib/backup_restore/database_restorer.rb

@@ -91,10 +91,10 @@ module BackupRestore
     end
 
     def restore_dump_command
-      "#{sed_command} #{@db_dump_path} | #{psql_command} 2>&1"
+      "#{sed_command} #{@db_dump_path} | #{self.class.psql_command} 2>&1"
     end
 
-    def psql_command
+    def self.psql_command
       db_conf = BackupRestore.database_configuration
 
       password_argument = "PGPASSWORD='#{db_conf.password}'" if db_conf.password.present?

spec/lib/backup_restore/database_restorer_spec.rb

@@ -69,17 +69,8 @@ describe BackupRestore::DatabaseRestorer do
 
     context "with real psql" do
       after do
-        DB.exec <<~SQL
-          -- Drop table and execute a commit to make the drop stick,
-          -- otherwise rspec will rollback the drop at the end of each test.
-          -- The tests in this context do not change the DB, so this should be safe.
-          DROP TABLE IF EXISTS foo;
-          COMMIT;
-
-          -- Start a new transaction in order to suppress the
-          -- "there is no transaction in progress" warnings from rspec.
-          BEGIN TRANSACTION;
-        SQL
+        psql = BackupRestore::DatabaseRestorer.psql_command
+        system("#{psql} -c 'DROP TABLE IF EXISTS foo'", [:out, :err] => File::NULL)
       end
 
       def restore(filename, stub_migrate: true)