data: Add Account.is_open_on_date() method.

conservancy_beancount/data.py

@@ -250,6 +250,22 @@ class Account(str):
     def is_credit_card(self) -> bool:
         return self.is_under('Liabilities:CreditCard') is not None
 
+    def is_open_on_date(self, date: datetime.date) -> Optional[bool]:
+        """Return true if this account is open on the given date.
+
+        This method considers the dates on the account's open and close
+        directives. If there is no close directive, it just checks the date is
+        on or after the opening date. If neither exists, returns None.
+        """
+        try:
+            meta = self.meta
+        except KeyError:
+            return None
+        close_date = meta.close_date
+        if close_date is None:
+            close_date = date + datetime.timedelta(days=1)
+        return meta.open_date <= date < close_date
+
     def is_opening_equity(self) -> bool:
         return self.is_under('Equity:Funds', 'Equity:OpeningBalance') is not None
 

tests/test_data_account.py

@@ -14,17 +14,17 @@
 # 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
 import pytest
 
 from . import testutil
 
-from datetime import date as Date
-
 from beancount.core.data import Open, Close, Booking
 from beancount.parser import options as bc_options
 
 from conservancy_beancount import data
 
+Date = datetime.date
 clean_account_meta = pytest.fixture()(testutil.clean_account_meta)
 
 @pytest.fixture
@@ -160,6 +160,50 @@ def test_is_credit_card(acct_name, expected):
 def test_is_opening_equity(acct_name, expected):
     assert data.Account(acct_name).is_opening_equity() == expected
 
+@pytest.mark.parametrize('date', [
+    testutil.PAST_DATE,
+    testutil.FY_START_DATE,
+    testutil.FY_MID_DATE,
+    testutil.FUTURE_DATE,
+])
+def test_is_open_on_date_without_opening(date):
+    account = data.Account('Assets:Cash')
+    assert account.is_open_on_date(date) is None
+
+@pytest.mark.parametrize('days_diff', range(-2, 3))
+def test_is_open_on_date_without_closing(clean_account_meta, days_diff):
+    open_date = testutil.FY_START_DATE
+    acct_name = 'Assets:Checking'
+    data.Account.load_opening(Open({}, open_date, acct_name, None, None))
+    account = data.Account(acct_name)
+    check_date = open_date + datetime.timedelta(days=days_diff)
+    assert account.is_open_on_date(check_date) == (days_diff >= 0)
+
+@pytest.mark.parametrize('close_diff,check_diff', [
+    (30, -30),
+    (30, -1),
+    (30, 0),
+    (30, 1),
+    (30, 29),
+    (30, 30),
+    (30, 60),
+    (60, 30),
+    (60, 59),
+    (60, 60),
+    (60, 90),
+    (60, -60),
+])
+def test_is_open_on_date_with_closing(clean_account_meta, close_diff, check_diff):
+    open_date = testutil.FY_START_DATE
+    acct_name = 'Assets:Savings'
+    data.Account.load_opening(Open({}, open_date, acct_name, None, None))
+    close_date = open_date + datetime.timedelta(days=close_diff)
+    data.Account.load_closing(Close({}, close_date, acct_name))
+    account = data.Account(acct_name)
+    check_date = open_date + datetime.timedelta(days=check_diff)
+    expected = (0 <= check_diff < close_diff)
+    assert account.is_open_on_date(check_date) == expected
+
 @pytest.mark.parametrize('acct_name', [
     'Assets:Cash',
     'Assets:Prepaid:Expenses',