Add set_user tools for test scenario

When changing the user of proteus, the context should be reloaded.

issue6652
review42551002

tests/scenario_account_dunning_letter.rst

@@ -8,7 +8,7 @@ Imports::
     >>> from dateutil.relativedelta import relativedelta
     >>> from decimal import Decimal
     >>> from proteus import config, Model, Wizard
-    >>> from trytond.tests.tools import activate_modules
+    >>> from trytond.tests.tools import activate_modules, set_user
     >>> from trytond.modules.company.tests.tools import create_company, \
     ...     get_company
     >>> from trytond.modules.account.tests.tools import create_fiscalyear, \
@@ -77,7 +77,7 @@ Create chart of accounts::
 
 Create dunning procedure::
 
-    >>> config.user = account_admin_user.id
+    >>> set_user(account_admin_user)
     >>> Procedure = Model.get('account.dunning.procedure')
     >>> procedure = Procedure(name='Procedure')
     >>> level = procedure.levels.new()
@@ -95,7 +95,7 @@ Create parties::
 
 Create some moves::
 
-    >>> config.user = account_user.id
+    >>> set_user(account_user)
     >>> Journal = Model.get('account.journal')
     >>> Move = Model.get('account.move')
     >>> journal_revenue, = Journal.find([
@@ -171,7 +171,7 @@ Add partial payment of 50::
 
 Create dunnings::
 
-    >>> config.user = dunning_user.id
+    >>> set_user(dunning_user)
     >>> Dunning = Model.get('account.dunning')
     >>> create_dunning = Wizard('account.dunning.create')
     >>> create_dunning.form.date = period.start_date + relativedelta(days=5)