Consistency checks for unit tests (#853)

models/models.go

@@ -30,6 +30,7 @@ import (
 
 // Engine represents a xorm engine or session.
 type Engine interface {
+	Count(interface{}) (int64, error)
 	Decr(column string, arg ...interface{}) *xorm.Session
 	Delete(interface{}) (int64, error)
 	Exec(string, ...interface{}) (sql.Result, error)