Add idempotency test of RegisterTxDb

pkg/pg/pg.go

@@ -14,10 +14,9 @@ import (
 
 func NewSqlxDB(t testing.TB, dbURL string) *sqlx.DB {
 	tests.SkipShortDB(t)
-
 	err := RegisterTxDb(dbURL)
 	if err != nil {
-		t.Errorf("failed to register txdb dialect: %w", err)
+		t.Errorf("failed to register txdb dialect: %s", err.Error())
 		return nil
 	}
 	db, err := sqlx.Open(string(TransactionWrappedPostgres), uuid.New().String())

pkg/pg/txdb.go

@@ -33,6 +33,13 @@ import (
 // See heavyweight.FullTestDB() as a convenience function to help you do this,
 // but please use sparingly because as it's name implies, it is expensive.
 func RegisterTxDb(dbURL string) error {
+	drivers := sql.Drivers()
+	for _, driver := range drivers {
+		if driver == string(TransactionWrappedPostgres) {
+			// TxDB driver already registered
+			return nil
+		}
+	}
 	testing.Init()
 	if !flag.Parsed() {
 		flag.Parse()