ledger: Correct period totals. RT#11661.

The period totals were reporting the balance of all the loaded postings, not
just the ones in the reporting date range.

Like the accrual report, introduce a RelatedPostings subclass that records
and saves all the information we need at group definition time, to help us
get it consistently right rather than redoing the same math over and over.

conservancy_beancount/reports/ledger.py

@@ -69,6 +69,7 @@ from pathlib import Path
 
 import odf.table  # type:ignore[import]
 
+from beancount.core import data as bc_data
 from beancount.parser import printer as bc_printer
 
 from . import core
@@ -84,6 +85,20 @@ PostTally = List[Tuple[int, data.Account]]
 PROGNAME = 'ledger-report'
 logger = logging.getLogger('conservancy_beancount.reports.ledger')
 
+class AccountPostings(core.RelatedPostings):
+    START_DATE: datetime.date
+
+    def __init__(self,
+                 source: Iterable[data.Posting]=(),
+                 *,
+                 _can_own: bool=False,
+    ) -> None:
+        super().__init__(source, _can_own=_can_own)
+        self.start_bal = self.balance_at_cost_by_date(self.START_DATE)
+        self.stop_bal = self.balance_at_cost()
+        self.period_bal = self.stop_bal - self.start_bal
+
+
 class LedgerODS(core.BaseODS[data.Posting, data.Account]):
     CORE_COLUMNS: Sequence[str] = [
         'Date',
@@ -268,17 +283,21 @@ class LedgerODS(core.BaseODS[data.Posting, data.Account]):
 
     def _report_section_balance(self, key: data.Account, date_key: str) -> None:
         uses_opening = key.is_under('Assets', 'Equity', 'Liabilities')
+        related = self.account_groups[key]
         if date_key == 'start':
             if not uses_opening:
                 return
             date = self.date_range.start
+            balance = related.start_bal
             description = "Opening Balance"
         else:
             date = self.date_range.stop
-            description = "Ending Balance" if uses_opening else "Period Total"
+            if uses_opening:
-        balance = self.norm_func(
+                balance = related.stop_bal
-            self.account_groups[key].balance_at_cost_by_date(date)
+                description = "Ending Balance"
-        )
+            else:
+                balance = related.period_bal
+                description = "Period Total"
         self.add_row(
             self.date_cell(date, stylename=self.merge_styles(
                 self.style_bold, self.style_date,
@@ -286,7 +305,7 @@ class LedgerODS(core.BaseODS[data.Posting, data.Account]):
             odf.table.TableCell(),
             self.string_cell(description, stylename=self.style_bold),
             odf.table.TableCell(),
-            self.balance_cell(balance, stylename=self.style_bold),
+            self.balance_cell(self.norm_func(balance), stylename=self.style_bold),
         )
 
     def start_section(self, key: data.Account) -> None:
@@ -327,11 +346,13 @@ class LedgerODS(core.BaseODS[data.Posting, data.Account]):
         )
 
     def _combined_balance_row(self,
-                              date: datetime.date,
                               balance_accounts: Sequence[str],
+                              attr_name: str,
     ) -> None:
+        date = getattr(self.date_range, attr_name)
+        balance_attrname = f'{attr_name}_bal'
         balance = -sum((
-            related.balance_at_cost_by_date(date)
+            getattr(related, balance_attrname)
             for account, related in self.account_groups.items()
             if account.is_under(*balance_accounts)
         ), core.MutableBalance())
@@ -365,23 +386,23 @@ class LedgerODS(core.BaseODS[data.Posting, data.Account]):
             numbercolumnsspanned=2,
         ))
         self.add_row()
-        self._combined_balance_row(self.date_range.start, balance_accounts)
+        self._combined_balance_row(balance_accounts, 'start')
         for _, account in self._sort_and_filter_accounts(
                 self.account_groups, balance_accounts,
         ):
-            related = self.account_groups[account]
+            balance = self.account_groups[account].period_bal
-            # start_bal - stop_bal == -(stop_bal - start_bal)
-            balance = related.balance_at_cost_by_date(self.date_range.start)
-            balance -= related.balance_at_cost_by_date(self.date_range.stop)
             if not balance.is_zero():
                 self.add_row(
                     self.string_cell(account, stylename=self.style_endtext),
-                    self.balance_cell(balance),
+                    self.balance_cell(-balance),
                 )
-        self._combined_balance_row(self.date_range.stop, balance_accounts)
+        self._combined_balance_row(balance_accounts, 'stop')
 
     def write(self, rows: Iterable[data.Posting]) -> None:
-        self.account_groups = dict(core.RelatedPostings.group_by_account(rows))
+        AccountPostings.START_DATE = self.date_range.start
+        self.account_groups = dict(AccountPostings.group_by_account(
+            post for post in rows if post.meta.date < self.date_range.stop
+        ))
         self.write_balance_sheet()
         tally_by_account_iter = (
             (account, sum(1 for post in related if post.meta.date in self.date_range))

setup.py

@@ -5,7 +5,7 @@ from setuptools import setup
 setup(
     name='conservancy_beancount',
     description="Plugin, library, and reports for reading Conservancy's books",
-    version='1.2.5',
+    version='1.2.6',
     author='Software Freedom Conservancy',
     author_email='info@sfconservancy.org',
     license='GNU AGPLv3+',

tests/test_reports_ledger.py

@@ -109,10 +109,12 @@ class ExpectedPostings(core.RelatedPostings):
                 raise NoHeader(account)
             else:
                 return
+        closing_bal = norm_func(expect_posts.balance_at_cost())
         if account.is_under('Assets', 'Equity', 'Liabilities'):
             opening_row = testutil.ODSCell.from_row(next(rows))
             assert opening_row[0].value == start_date
             assert opening_row[4].text == open_bal.format(None, empty='0', sep='\0')
+            closing_bal += open_bal
         for expected in expect_posts:
             cells = iter(testutil.ODSCell.from_row(next(rows)))
             assert next(cells).value == expected.meta.date
@@ -125,7 +127,6 @@ class ExpectedPostings(core.RelatedPostings):
                 assert next(cells).value == norm_func(expected.units.number)
                 assert next(cells).value == norm_func(expected.at_cost().number)
         closing_row = testutil.ODSCell.from_row(next(rows))
-        closing_bal = open_bal + norm_func(expect_posts.balance_at_cost())
         assert closing_row[0].value == end_date
         assert closing_row[4].text == closing_bal.format(None, empty='0', sep='\0')