expenseAllocation: Date-limit the transactions we work on.

This prevents the plugin from giving meaning to postings that
might not really be there.

conservancy_beancount/plugin/core.py

@@ -14,10 +14,31 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+import datetime
+
 from . import errors as errormod
 
+DEFAULT_START_DATE = datetime.date(2020, 3, 1)
+DEFAULT_STOP_DATE = datetime.date(datetime.MAXYEAR, 1, 1)
+
+class _GenericRange:
+    def __init__(self, start, stop):
+        self.start = start
+        self.stop = stop
+
+    def __repr__(self):
+        return "{clsname}({self.start!r}, {self.stop!r})".format(
+            clsname=type(self).__name__,
+            self=self,
+        )
+
+    def __contains__(self, item):
+        return self.start <= item < self.stop
+
+
 class PostingChecker:
     ACCOUNTS = ('',)
+    TXN_DATE_RANGE = _GenericRange(DEFAULT_START_DATE, DEFAULT_STOP_DATE)
     VALUES_ENUM = {}
 
     def _meta_get(self, txn, post, key, default=None):
@@ -35,7 +56,7 @@ class PostingChecker:
         raise errormod.InvalidMetadataError(txn, post, self.METADATA_KEY)
 
     def _should_check(self, txn, post):
-        ok = True
+        ok = txn.date in self.TXN_DATE_RANGE
         if isinstance(self.ACCOUNTS, tuple):
             ok = ok and post.account.startswith(self.ACCOUNTS)
         else:

tests/test_meta_expenseAllocation.py

@@ -109,3 +109,21 @@ def test_default_values(account, set_value):
     errors = checker.check(txn, txn.postings[-1])
     assert not errors
     assert txn.postings[-1].meta['expenseAllocation'] == set_value
+
+@pytest.mark.parametrize('date,set_value', [
+    (testutil.EXTREME_FUTURE_DATE, False),
+    (testutil.FUTURE_DATE, True),
+    (testutil.FY_START_DATE, True),
+    (testutil.FY_MID_DATE, True),
+    (testutil.PAST_DATE, False),
+])
+def test_default_value_set_in_date_range(date, set_value):
+    txn = testutil.Transaction(date=date, postings=[
+        ('Liabilites:CreditCard', -25),
+        ('Expenses:General', 25),
+    ])
+    checker = meta_expense_allocation.MetaExpenseAllocation()
+    errors = checker.check(txn, txn.postings[-1])
+    assert not errors
+    got_value = (txn.postings[-1].meta or {}).get('expenseAllocation')
+    assert bool(got_value) == bool(set_value)

tests/testutil.py

@@ -21,8 +21,11 @@ import beancount.core.data as bc_data
 
 from decimal import Decimal
 
+EXTREME_FUTURE_DATE = datetime.date(datetime.MAXYEAR, 12, 30)
+FUTURE_DATE = datetime.date.today() + datetime.timedelta(days=365 * 99)
 FY_START_DATE = datetime.date(2020, 3, 1)
 FY_MID_DATE = datetime.date(2020, 9, 1)
+PAST_DATE = datetime.date(2000, 1, 1)
 
 def parse_date(s, fmt='%Y-%m-%d'):
     return datetime.datetime.strptime(s, fmt).date()