tests: Test where Transactions are real NamedTuples.

This makes methods like _replace available in real code, and caught the
bug where we can't use @functools.lru_cache with Transaction arguments,
because they're unhashable due to their mutable members.

conservancy_beancount/data.py

@@ -31,11 +31,13 @@ from beancount.core import convert as bc_convert
 from typing import (
     cast,
     Callable,
+    Hashable,
     Iterable,
     Iterator,
     MutableMapping,
     Optional,
     Sequence,
+    TypeVar,
     Union,
 )
 
@@ -310,6 +312,19 @@ class Posting(BasePosting):
                 pass
 
 
+_KT = TypeVar('_KT', bound=Hashable)
+_VT = TypeVar('_VT')
+class _SizedDict(collections.OrderedDict, MutableMapping[_KT, _VT]):
+    def __init__(self, maxsize: int=128) -> None:
+        self.maxsize = maxsize
+        super().__init__()
+
+    def __setitem__(self, key: _KT, value: _VT) -> None:
+        super().__setitem__(key, value)
+        for _ in range(self.maxsize, len(self)):
+            self.popitem(last=False)
+
+
 def balance_of(txn: Transaction,
                *preds: Callable[[Account], Optional[bool]],
 ) -> Amount:
@@ -335,12 +350,23 @@ def balance_of(txn: Transaction,
         currency = weights[0].currency
     return Amount(number, currency)
 
-@functools.lru_cache()
+_opening_balance_cache: MutableMapping[str, bool] = _SizedDict()
 def is_opening_balance_txn(txn: Transaction) -> bool:
+    key = '\0'.join(
+        f'{post.account}={post.units}' for post in txn.postings
+    )
+    try:
+        return _opening_balance_cache[key]
+    except KeyError:
+        pass
     opening_equity = balance_of(txn, Account.is_opening_equity)
     if not opening_equity.currency:
-        return False
+        retval = False
-    rest = balance_of(txn, lambda acct: not acct.is_opening_equity())
+    else:
-    if not rest.currency:
+        rest = balance_of(txn, lambda acct: not acct.is_opening_equity())
-        return False
+        if not rest.currency:
-    return abs(opening_equity.number + rest.number) < decimal.Decimal('.01')
+            retval = False
+        else:
+            retval = abs(opening_equity.number + rest.number) < decimal.Decimal('.01')
+    _opening_balance_cache[key] = retval
+    return retval

tests/test_data_is_opening_balance_txn.py

@@ -23,7 +23,7 @@ from . import testutil
 from conservancy_beancount import data
 
 def test_typical_opening():
-    txn = testutil.Transaction.opening_balance()
+    txn = testutil.OpeningBalance()
     assert data.is_opening_balance_txn(txn)
 
 def test_multiacct_opening():
@@ -36,7 +36,7 @@ def test_multiacct_opening():
     assert data.is_opening_balance_txn(txn)
 
 def test_opening_with_fx():
-    txn = testutil.Transaction.opening_balance()
+    txn = testutil.OpeningBalance()
     equity_post = txn.postings[-1]
     txn.postings[-1] = equity_post._replace(
         units=testutil.Amount(equity_post.units.number * Decimal('.9'), 'EUR'),

tests/test_meta_entity.py

@@ -167,5 +167,5 @@ def test_which_accounts_required_on(hook, account, required):
                    for error in errors)
 
 def test_not_required_on_opening(hook):
-    txn = testutil.Transaction.opening_balance()
+    txn = testutil.OpeningBalance()
     assert not list(hook.run(txn))

tests/test_meta_invoice.py

@@ -142,5 +142,5 @@ def test_missing_invoice(hook, acct1, acct2):
     assert actual == {"{} missing {}".format(acct1, TEST_KEY)}
 
 def test_not_required_on_opening(hook):
-    txn = testutil.Transaction.opening_balance()
+    txn = testutil.OpeningBalance()
     assert not list(hook.run(txn))

tests/test_meta_project.py

@@ -158,11 +158,11 @@ def test_invalid_project_data(repo_path_s, data_path_s):
         meta_project.MetaProject(config, Path(data_path_s))
 
 def test_not_required_on_opening(hook):
-    txn = testutil.Transaction.opening_balance('Equity:Funds:Unrestricted')
+    txn = testutil.OpeningBalance('Equity:Funds:Unrestricted')
     assert not list(hook.run(txn))
 
 def test_always_required_on_restricted_funds(hook):
     acct = 'Equity:Funds:Restricted'
-    txn = testutil.Transaction.opening_balance(acct)
+    txn = testutil.OpeningBalance(acct)
     actual = {error.message for error in hook.run(txn)}
     assert actual == {f'{acct} missing project'}

tests/testutil.py

@@ -93,6 +93,37 @@ def Posting(account, number,
         meta,
     )
 
+def Transaction(date=FY_MID_DATE, flag='*', payee=None,
+                narration='', tags=None, links=None, postings=(),
+                **meta):
+    if isinstance(date, str):
+        date = parse_date(date)
+    meta.setdefault('filename', '<test>')
+    meta.setdefault('lineno', 0)
+    real_postings = []
+    for post in postings:
+        try:
+            post.account
+        except AttributeError:
+            if isinstance(post[-1], dict):
+                args = post[:-1]
+                kwargs = post[-1]
+            else:
+                args = post
+                kwargs = {}
+            post = Posting(*args, **kwargs)
+        real_postings.append(post)
+    return bc_data.Transaction(
+        meta,
+        date,
+        flag,
+        payee,
+        narration,
+        set(tags or ''),
+        set(links or ''),
+        real_postings,
+    )
+
 LINK_METADATA_STRINGS = {
     'Invoices/304321.pdf',
     'rt:123/456',
@@ -130,59 +161,16 @@ def balance_map(source=None, **kwargs):
         retval.update(balance_map(kwargs.items()))
     return retval
 
-class Transaction:
+def OpeningBalance(acct=None, **txn_meta):
-    def __init__(self,
+    if acct is None:
-                 date=FY_MID_DATE, flag='*', payee=None,
+        acct = next(OPENING_EQUITY_ACCOUNTS)
-                 narration='', tags=None, links=None, postings=None,
+    return Transaction(**txn_meta, postings=[
-                 **meta):
+        ('Assets:Receivable:Accounts', 100),
-        if isinstance(date, str):
+        ('Assets:Receivable:Loans', 200),
-            date = parse_date(date)
+        ('Liabilities:Payable:Accounts', -15),
-        self.date = date
+        ('Liabilities:Payable:Vacation', -25),
-        self.flag = flag
+        (acct, -260),
-        self.payee = payee
+    ])
-        self.narration = narration
-        self.tags = set(tags or '')
-        self.links = set(links or '')
-        self.postings = []
-        self.meta = {
-            'filename': '<test>',
-            'lineno': 0,
-        }
-        self.meta.update(meta)
-        if postings is not None:
-            for posting in postings:
-                self.add_posting(*posting)
-
-    def add_posting(self, arg, *args, **kwargs):
-        """Add a posting to this transaction. Use any of these forms:
-
-           txn.add_posting(account, number, …, kwarg=value, …)
-           txn.add_posting(account, number, …, posting_kwargs_dict)
-           txn.add_posting(posting_object)
-        """
-        if kwargs:
-            posting = Posting(arg, *args, **kwargs)
-        elif args:
-            if isinstance(args[-1], dict):
-                kwargs = args[-1]
-                args = args[:-1]
-            posting = Posting(arg, *args, **kwargs)
-        else:
-            posting = arg
-        self.postings.append(posting)
-
-    @classmethod
-    def opening_balance(cls, acct=None, **txn_meta):
-        if acct is None:
-            acct = next(OPENING_EQUITY_ACCOUNTS)
-        return cls(**txn_meta, postings=[
-            ('Assets:Receivable:Accounts', 100),
-            ('Assets:Receivable:Loans', 200),
-            ('Liabilities:Payable:Accounts', -15),
-            ('Liabilities:Payable:Vacation', -25),
-            (acct, -260),
-        ])
-
 
 class TestConfig:
     def __init__(self, *,