Fix savings_goal report

- remove multiplier from configuration, needs to be implemented differently (in a way that supports account walkers).
- Allow for null accounts in account walker, for when data is going to be updated by hand
- savings_goal report now uses account walker for calculating the value of accounts and descendants.

gnucash_reports/reports/savings_goals.py

@@ -8,13 +8,11 @@
 from gnucash_reports.configuration.current_date import get_today
 from gnucash_reports.configuration.currency import get_currency
 from gnucash_reports.periods import PeriodStart
-from gnucash_reports.wrapper import get_account, get_balance_on_date, account_walker
+from gnucash_reports.wrapper import get_account, get_balance_on_date, account_walker, parse_walker_parameters
 
 
 def savings_goal(definition):
-    accounts = definition['account']
-    if isinstance(accounts, basestring):
-        accounts = [accounts]
+    walker_params = parse_walker_parameters(definition['savings'])
 
     goal_amount = Decimal(definition.get('goal', Decimal(0.0)))
 
@@ -27,17 +25,9 @@ def savings_goal(definition):
     total_balance = Decimal('0.0')
     currency = get_currency()
 
-    for account_description in accounts:
-        multiplier = Decimal('1.0')
-        if isinstance(account_description, basestring):
-            account = account_description
-        else:
-            account = account_description[0]
-            multiplier = Decimal(account_description[1])
-
-        for account_name in account_walker([account]):
-            balance = get_balance_on_date(account_name, as_of.date, currency)
-            total_balance += (balance * multiplier)
+    for account in account_walker(**walker_params):
+        balance = get_balance_on_date(account, as_of.date, currency)
+        total_balance += balance
 
     for contribution in contributions:
         total_balance += Decimal(contribution)

gnucash_reports/wrapper.py

@@ -98,6 +98,10 @@ def account_walker(accounts, ignores=None, place_holders=False, recursive=True,
     if not ignores:
         ignores = []
 
+    # Allow for a none account list to be provided
+    if accounts is None:
+        accounts = []
+
     _account_list = [a for a in accounts]
 
     while _account_list:
@@ -125,6 +129,10 @@ def parse_walker_parameters(definition):
         'recursive': True
     }
 
+    # Allow for a none definition to be provided and overwrite to an empty list
+    if definition is None:
+        definition = []
+
     if isinstance(definition, dict):
         return_value.update(definition)
     elif isinstance(definition, list) or isinstance(definition, set):