asset: Feld 'change_symbol' für Prozenzzeichen + test

rate.py

@@ -3,13 +3,13 @@
 # The COPYRIGHT file at the top level of this repository contains the
 # full copyright notices and license terms.
 
-from trytond.model import ModelView, ModelSQL, fields, Unique, Check
+from trytond.model import ModelView, ModelSQL, fields, Unique, Check, SymbolMixin
 from trytond.transaction import Transaction
 from trytond.pool import Pool
 from trytond.pyson import Eval, Bool
 
 
-class Rate(ModelSQL, ModelView):
+class Rate(SymbolMixin, ModelSQL, ModelView):
     'Rate'
     __name__ = 'investment.rate'
 
@@ -29,6 +29,8 @@ class Rate(ModelSQL, ModelView):
     uom = fields.Function(fields.Many2One(string='Uom',
         readonly=True, model_name='product.uom'),
         'on_change_with_uom')
+    symbol = fields.Function(fields.Char(string='Symbol',
+        readonly=True), 'on_change_with_symbol')
 
     @classmethod
     def __setup__(cls):
@@ -51,6 +53,11 @@ class Rate(ModelSQL, ModelView):
         IrDate = Pool().get('ir.date')
         return IrDate.today()
 
+    def on_change_with_symbol(self, name=None):
+        """ symbol:%
+        """
+        return '%'
+
     @fields.depends('asset', '_parent_asset.uom')
     def on_change_with_uom(self, name=None):
         """ get unit of asset