reports: Add account_balances() function.

conservancy_beancount/reports/core.py

@@ -68,6 +68,9 @@ from ..beancount_types import (
     MetaValue,
 )
 
+OPENING_BALANCE_NAME = "OPENING BALANCE"
+ENDING_BALANCE_NAME = "ENDING BALANCE"
+
 DecimalCompat = data.DecimalCompat
 BalanceType = TypeVar('BalanceType', bound='Balance')
 ElementType = Callable[..., odf.element.Element]
@@ -1104,6 +1107,50 @@ class BaseODS(BaseSpreadsheet[RT, ST], metaclass=abc.ABCMeta):
             self.save_file(out_file)
 
 
+def account_balances(
+        groups: Mapping[data.Account, PeriodPostings],
+        order: Optional[Sequence[str]]=None,
+) -> Iterator[Tuple[str, Balance]]:
+    """Iterate account balances over a date range
+
+    1. ``subclass = PeriodPostings.with_start_date(start_date)``
+    2. ``groups = dict(subclass.group_by_account(postings))``
+    3. ``for acct, bal in account_balances(groups, [optional ordering]): ...``
+
+    This function returns an iterator of 2-tuples ``(account, balance)``
+    that you can use to generate a report in the style of ``ledger balance``.
+    The accounts are accounts in ``groups`` that appeared under one of the
+    account name strings in ``order``. ``balance`` is the corresponding
+    balance over the time period (``groups[key].period_bal``). Accounts are
+    iterated in the order provided by ``sort_and_filter_accounts()``.
+
+    The first 2-tuple is ``(OPENING_BALANCE_NAME, balance)`` with the balance of
+    all these accounts as of ``start_date``.
+    The final 2-tuple is ``(ENDING_BALANCE_NAME, balance)`` with the final
+    balance of all these accounts as of ``start_date``.
+    The iterator will always yield these special 2-tuples, even when there are
+    no accounts in the input or to report.
+    """
+    if order is None:
+        order = ['Equity', 'Income', 'Expenses']
+    acct_seq = [account for _, account in sort_and_filter_accounts(groups, order)]
+    yield (OPENING_BALANCE_NAME, sum(
+        (groups[key].start_bal for key in acct_seq),
+        MutableBalance(),
+    ))
+    for key in acct_seq:
+        postings = groups[key]
+        try:
+            in_date_range = postings[-1].meta.date >= postings.START_DATE
+        except IndexError:
+            in_date_range = False
+        if in_date_range:
+            yield (key, groups[key].period_bal)
+    yield (ENDING_BALANCE_NAME, sum(
+        (groups[key].stop_bal for key in acct_seq),
+        MutableBalance(),
+    ))
+
 def normalize_amount_func(account_name: str) -> Callable[[T], T]:
     """Get a function to normalize amounts for reporting
 

conservancy_beancount/reports/ledger.py

@@ -312,27 +312,7 @@ class LedgerODS(core.BaseODS[data.Posting, data.Account]):
               for key in self.metadata_columns),
         )
 
-    def _combined_balance_row(self,
-                              balance_accounts: Sequence[str],
-                              attr_name: str,
-    ) -> None:
-        date = getattr(self.date_range, attr_name)
-        balance_attrname = f'{attr_name}_bal'
-        balance = -sum((
-            getattr(related, balance_attrname)
-            for account, related in self.account_groups.items()
-            if account.is_under(*balance_accounts)
-        ), core.MutableBalance())
-        self.add_row(
-            self.string_cell(
-                f"Balance as of {date.isoformat()}",
-                stylename=self.merge_styles(self.style_bold, self.style_endtext),
-            ),
-            self.balance_cell(balance, stylename=self.style_bold),
-        )
-
     def write_balance_sheet(self) -> None:
-        balance_accounts = ['Equity', 'Income', 'Expenses']
         self.use_sheet("Balance")
         self.sheet.addElement(odf.table.TableColumn(stylename=self.column_style(3)))
         self.sheet.addElement(odf.table.TableColumn(stylename=self.column_style(1.5)))
@@ -349,17 +329,20 @@ class LedgerODS(core.BaseODS[data.Posting, data.Account]):
             numbercolumnsspanned=2,
         ))
         self.add_row()
-        self._combined_balance_row(balance_accounts, 'start')
+        for account, balance in core.account_balances(self.account_groups):
-        for _, account in core.sort_and_filter_accounts(
+            if account is core.OPENING_BALANCE_NAME:
-                self.account_groups, balance_accounts,
+                text = f"Balance as of {self.date_range.start.isoformat()}"
-        ):
+                style = self.merge_styles(self.style_bold, self.style_endtext)
-            balance = self.account_groups[account].period_bal
+            elif account is core.ENDING_BALANCE_NAME:
-            if not balance.is_zero():
+                text = f"Balance as of {self.date_range.stop.isoformat()}"
+                style = self.merge_styles(self.style_bold, self.style_endtext)
+            else:
+                text = account
+                style = self.style_endtext
             self.add_row(
-                    self.string_cell(account, stylename=self.style_endtext),
+                self.string_cell(text, stylename=style),
-                    self.balance_cell(-balance),
+                self.balance_cell(-balance, stylename=style),
             )
-        self._combined_balance_row(balance_accounts, 'stop')
 
     def write(self, rows: Iterable[data.Posting]) -> None:
         related_cls = core.PeriodPostings.with_start_date(self.date_range.start)

tests/test_reports_core.py

@@ -14,16 +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 decimal import Decimal
 
 from . import testutil
 
+from conservancy_beancount import data
 from conservancy_beancount.reports import core
 
-from conservancy_beancount.data import Account
-
 AMOUNTS = [
     2,
     Decimal('4.40'),
@@ -31,6 +32,27 @@ AMOUNTS = [
     core.Balance([testutil.Amount('8.80')]),
 ]
 
+@pytest.fixture
+def balance_postings():
+    dates = testutil.date_seq(testutil.FY_MID_DATE)
+    return data.Posting.from_entries([
+        testutil.Transaction(date=next(dates), postings=[
+            ('Equity:OpeningBalance', -1000),
+            ('Assets:Checking', 1000),
+        ]),
+        testutil.Transaction(date=next(dates), postings=[
+            ('Income:Donations', -10),
+            ('Expenses:BankingFees', 1),
+            ('Assets:Checking', 9),
+        ]),
+        testutil.Transaction(date=next(dates), postings=[
+            ('Income:Donations', -20),
+            ('Expenses:Services:Fundraising', 1),
+            ('Equity:Realized:CurrencyConversion', 1),
+            ('Assets:Checking', 18),
+        ]),
+    ])
+
 @pytest.mark.parametrize('acct_name', [
     'Assets:Checking',
     'Assets:Receivable:Accounts',
@@ -68,7 +90,7 @@ def test_normalize_amount_func_bad_acct_name(acct_name):
         core.normalize_amount_func(acct_name)
 
 def test_sort_and_filter_accounts():
-    accounts = (Account(s) for s in [
+    accounts = (data.Account(s) for s in [
         'Expenses:Services',
         'Assets:Receivable',
         'Income:Other',
@@ -87,7 +109,7 @@ def test_sort_and_filter_accounts():
     ]
 
 def test_sort_and_filter_accounts_unused_name():
-    accounts = (Account(s) for s in [
+    accounts = (data.Account(s) for s in [
         'Liabilities:CreditCard',
         'Assets:Cash',
         'Assets:Receivable:Accounts',
@@ -102,7 +124,7 @@ def test_sort_and_filter_accounts_unused_name():
     ]
 
 def test_sort_and_filter_accounts_with_subaccounts():
-    accounts = (Account(s) for s in [
+    accounts = (data.Account(s) for s in [
         'Assets:Checking',
         'Assets:Receivable:Fraud',
         'Assets:Cash',
@@ -118,10 +140,79 @@ def test_sort_and_filter_accounts_with_subaccounts():
 
 @pytest.mark.parametrize('empty_arg', ['accounts', 'order'])
 def test_sort_and_filter_accounts_empty_accounts(empty_arg):
-    accounts = [Account(s) for s in ['Expenses:Other', 'Income:Other']]
+    accounts = [data.Account(s) for s in ['Expenses:Other', 'Income:Other']]
     if empty_arg == 'accounts':
         args = ([], accounts)
     else:
         args = (accounts, [])
     actual = core.sort_and_filter_accounts(*args)
     assert next(actual, None) is None
+
+def check_account_balance(balance_seq, account, balance):
+    assert next(balance_seq, None) == (account, {'USD': testutil.Amount(balance)})
+
+@pytest.mark.parametrize('days_after', range(4))
+def test_account_balances(balance_postings, days_after):
+    start_date = testutil.FY_MID_DATE + datetime.timedelta(days=days_after)
+    balance_cls = core.PeriodPostings.with_start_date(start_date)
+    groups = dict(balance_cls.group_by_account(balance_postings))
+    actual = core.account_balances(groups)
+    expect_opening = -1027
+    opening_acct, opening_bal = next(actual)
+    if days_after < 1:
+        check_account_balance(actual, 'Equity:OpeningBalance', -1000)
+        expect_opening += 1000
+    if days_after < 3:
+        check_account_balance(actual, 'Equity:Realized:CurrencyConversion', 1)
+        expect_opening -= 1
+    if days_after < 2:
+        check_account_balance(actual, 'Income:Donations', -30)
+        expect_opening += 30
+    elif days_after < 3:
+        check_account_balance(actual, 'Income:Donations', -20)
+        expect_opening += 20
+    if days_after < 2:
+        check_account_balance(actual, 'Expenses:BankingFees', 1)
+        expect_opening -= 1
+    if days_after < 3:
+        check_account_balance(actual, 'Expenses:Services:Fundraising', 1)
+        expect_opening -= 1
+    if expect_opening:
+        assert opening_bal == {'USD': testutil.Amount(expect_opening)}
+    else:
+        assert opening_bal.is_zero()
+    assert opening_acct == core.OPENING_BALANCE_NAME
+    check_account_balance(actual, core.ENDING_BALANCE_NAME, -1027)
+    assert next(actual, None) is None
+
+def test_account_balances_order_arg(balance_postings):
+    start_date = testutil.FY_MID_DATE + datetime.timedelta(days=1)
+    balance_cls = core.PeriodPostings.with_start_date(start_date)
+    groups = dict(balance_cls.group_by_account(balance_postings))
+    actual = core.account_balances(groups, ['Income', 'Assets'])
+    check_account_balance(actual, core.OPENING_BALANCE_NAME, 1000)
+    check_account_balance(actual, 'Income:Donations', -30)
+    check_account_balance(actual, 'Assets:Checking', 27)
+    check_account_balance(actual, core.ENDING_BALANCE_NAME, 997)
+    assert next(actual, None) is None
+
+def test_account_balances_order_filters_all(balance_postings):
+    start_date = testutil.FY_MID_DATE + datetime.timedelta(days=1)
+    balance_cls = core.PeriodPostings.with_start_date(start_date)
+    groups = dict(balance_cls.group_by_account(balance_postings))
+    actual = core.account_balances(groups, ['Liabilities'])
+    account, balance = next(actual)
+    assert account is core.OPENING_BALANCE_NAME
+    assert balance.is_zero()
+    account, balance = next(actual)
+    assert account is core.ENDING_BALANCE_NAME
+    assert balance.is_zero()
+
+def test_account_balances_empty_postings():
+    actual = core.account_balances({})
+    account, balance = next(actual)
+    assert account is core.OPENING_BALANCE_NAME
+    assert balance.is_zero()
+    account, balance = next(actual)
+    assert account is core.ENDING_BALANCE_NAME
+    assert balance.is_zero()