add ErrReadOnlyTxNotSupported error

Author: shogo82148

connection_go18.go

@@ -78,6 +78,9 @@ func (mc *mysqlConn) beginReadOnly() (driver.Tx, error) {
 	}
 	err := mc.exec("START TRANSACTION READ ONLY")
 	if err != nil {
+		if _, ok := err.(*MySQLError); ok {
+			return nil, ErrReadOnlyTxNotSupported
+		}
 		return nil, err
 	}
 

driver_go18_test.go

@@ -478,7 +478,7 @@ func TestContextBeginReadOnly(t *testing.T) {
 		tx, err := dbt.db.BeginTx(ctx, &sql.TxOptions{
 			ReadOnly: true,
 		})
-		if _, ok := err.(*MySQLError); ok {
+		if err == ErrReadOnlyTxNotSupported {
 			dbt.Skip("It seems that your MySQL does not support READ ONLY transactions")
 			return
 		} else if err != nil {

errors.go

@@ -19,18 +19,19 @@ import (
 
 // Various errors the driver might return. Can change between driver versions.
 var (
-	ErrInvalidConn       = errors.New("invalid connection")
-	ErrMalformPkt        = errors.New("malformed packet")
-	ErrNoTLS             = errors.New("TLS requested but server does not support TLS")
-	ErrCleartextPassword = errors.New("this user requires clear text authentication. If you still want to use it, please add 'allowCleartextPasswords=1' to your DSN")
-	ErrNativePassword    = errors.New("this user requires mysql native password authentication.")
-	ErrOldPassword       = errors.New("this user requires old password authentication. If you still want to use it, please add 'allowOldPasswords=1' to your DSN. See also https://github.com/go-sql-driver/mysql/wiki/old_passwords")
-	ErrUnknownPlugin     = errors.New("this authentication plugin is not supported")
-	ErrOldProtocol       = errors.New("MySQL server does not support required protocol 41+")
-	ErrPktSync           = errors.New("commands out of sync. You can't run this command now")
-	ErrPktSyncMul        = errors.New("commands out of sync. Did you run multiple statements at once?")
-	ErrPktTooLarge       = errors.New("packet for query is too large. Try adjusting the 'max_allowed_packet' variable on the server")
-	ErrBusyBuffer        = errors.New("busy buffer")
+	ErrInvalidConn            = errors.New("invalid connection")
+	ErrMalformPkt             = errors.New("malformed packet")
+	ErrNoTLS                  = errors.New("TLS requested but server does not support TLS")
+	ErrCleartextPassword      = errors.New("this user requires clear text authentication. If you still want to use it, please add 'allowCleartextPasswords=1' to your DSN")
+	ErrNativePassword         = errors.New("this user requires mysql native password authentication.")
+	ErrOldPassword            = errors.New("this user requires old password authentication. If you still want to use it, please add 'allowOldPasswords=1' to your DSN. See also https://github.com/go-sql-driver/mysql/wiki/old_passwords")
+	ErrUnknownPlugin          = errors.New("this authentication plugin is not supported")
+	ErrOldProtocol            = errors.New("MySQL server does not support required protocol 41+")
+	ErrPktSync                = errors.New("commands out of sync. You can't run this command now")
+	ErrPktSyncMul             = errors.New("commands out of sync. Did you run multiple statements at once?")
+	ErrPktTooLarge            = errors.New("packet for query is too large. Try adjusting the 'max_allowed_packet' variable on the server")
+	ErrBusyBuffer             = errors.New("busy buffer")
+	ErrReadOnlyTxNotSupported = errors.New("read-only transactions not supported")
 )
 
 var errLog = Logger(log.New(os.Stderr, "[mysql] ", log.Ldate|log.Ltime|log.Lshortfile))