add more tests for sqlx (#442)

* add more tests for sqlx

* add more tests for sqlx

core/stores/sqlx/mysql_test.go

@@ -1,6 +1,8 @@
 package sqlx
 
 import (
+	"errors"
+	"reflect"
 	"testing"
 
 	"github.com/go-sql-driver/mysql"
@@ -33,6 +35,15 @@ func TestBreakerOnNotHandlingDuplicateEntry(t *testing.T) {
 	assert.True(t, found)
 }
 
+func TestMysqlAcceptable(t *testing.T) {
+	conn := NewMysql("nomysql").(*commonSqlConn)
+	withMysqlAcceptable()(conn)
+	assert.EqualValues(t, reflect.ValueOf(mysqlAcceptable).Pointer(), reflect.ValueOf(conn.accept).Pointer())
+	assert.True(t, mysqlAcceptable(nil))
+	assert.False(t, mysqlAcceptable(errors.New("any")))
+	assert.False(t, mysqlAcceptable(new(mysql.MySQLError)))
+}
+
 func tryOnDuplicateEntryError(t *testing.T, accept func(error) bool) error {
 	logx.Disable()