Dirty SQL test system

* Added a system that allows "dirty" tests to be written. These tests
actually need to change the database, so a temporary test database must
be created to run them.

legacyworlds-server-data/db-structure/tests/dirty/000-dirty-tests-self-check/prepare.sql

@@ -0,0 +1,23 @@
+/*
+ * Dirty test system self-check
+ *
+ * Insert an address, it should exist during the main test. Also create a
+ * function and a table which are used to synchronise execution.
+ */
+BEGIN;
+	INSERT INTO users.addresses ( address )
+		VALUES ( 'prepare@example.org' );
+
+	CREATE TABLE _barriers( _barrier BIGINT );
+
+	CREATE FUNCTION _synchronise_tests( _lock BIGINT )
+		RETURNS VOID
+	AS $$
+	BEGIN
+		WHILE pg_try_advisory_lock( _lock )
+		LOOP
+			PERFORM pg_advisory_unlock( _lock );
+		END LOOP;
+	END;
+	$$ LANGUAGE PLPGSQL;
+COMMIT;

legacyworlds-server-data/db-structure/tests/dirty/000-dirty-tests-self-check/run-test.sql

@@ -0,0 +1,17 @@
+/*
+ * Dirty test system self-check
+ *
+ * Insert an address, it should exist during the main test.
+ */
+BEGIN;
+	SELECT no_plan( );
+
+	SELECT pg_advisory_lock( 1 );
+
+	SELECT diag_test_name( 'Dirty test system self-check - prepare.sql was executed' );
+	SELECT is( COUNT(*)::INT , 1 )
+		FROM users.addresses
+		WHERE address = 'prepare@example.org';
+
+	SELECT * FROM finish( );
+ROLLBACK;