Change type of Client.db to be an interface

This will be helpful soon when we add the Transactions feature

kiss_orm.go

@@ -13,7 +13,12 @@ type DB struct {
 	driver    string
 	dialect   dialect
 	tableName string
-	db        *sql.DB
+	db        sqlProvider
+}
+
+type sqlProvider interface {
+	ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error)
+	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
 }
 
 // New instantiates a new client

kiss_orm_test.go

@@ -952,7 +952,9 @@ func shiftErrSlice(errs *[]error) error {
 	return err
 }
 
-func getUsersByID(db *sql.DB, dialect dialect, resultsPtr *[]User, ids ...uint) error {
+func getUsersByID(dbi sqlProvider, dialect dialect, resultsPtr *[]User, ids ...uint) error {
+	db := dbi.(*sql.DB)
+
 	placeholders := make([]string, len(ids))
 	params := make([]interface{}, len(ids))
 	for i := range ids {
@@ -992,7 +994,9 @@ func getUsersByID(db *sql.DB, dialect dialect, resultsPtr *[]User, ids ...uint)
 	return nil
 }
 
-func getUserByID(db *sql.DB, dialect dialect, result *User, id uint) error {
+func getUserByID(dbi sqlProvider, dialect dialect, result *User, id uint) error {
+	db := dbi.(*sql.DB)
+
 	row := db.QueryRow(`SELECT id, name, age FROM users WHERE id=`+dialect.Placeholder(0), id)
 	if row.Err() != nil {
 		return row.Err()