reports: Add Balance.__str__() method.

conservancy_beancount/reports/core.py

@@ -60,6 +60,13 @@ class Balance(Mapping[str, data.Amount]):
     def __repr__(self) -> str:
         return f"{type(self).__name__}({self._currency_map!r})"
 
+    def __str__(self) -> str:
+        amounts = [amount for amount in self.values() if amount.number]
+        if not amounts:
+            return "Zero balance"
+        amounts.sort(key=lambda amt: abs(amt.number), reverse=True)
+        return ', '.join(str(amount) for amount in amounts)
+
     def __getitem__(self, key: str) -> data.Amount:
         return data.Amount(self._currency_map[key], key)
 

tests/test_reports_balance.py

@@ -66,3 +66,14 @@ def test_mixed_balance():
     assert len(balance) == 2
     assert not balance.is_zero()
     assert all(balance[key] == amt for key, amt in amounts.items())
+
+@pytest.mark.parametrize('balance_map_kwargs,expected', [
+    ({}, "Zero balance"),
+    ({'JPY': 0, 'BRL': 0}, "Zero balance"),
+    ({'USD': '20.00'}, "20.00 USD"),
+    ({'EUR': '50.00', 'GBP': '80.00'}, "80.00 GBP, 50.00 EUR"),
+    ({'JPY': '-55.00', 'BRL': '-85.00'}, "-85.00 BRL, -55.00 JPY"),
+])
+def test_str(balance_map_kwargs, expected):
+    amounts = testutil.balance_map(**balance_map_kwargs)
+    assert str(core.Balance(amounts.items())) == expected