add tests for the new swap_currencies() function

liberapay/billing/transactions.py

@@ -576,11 +576,11 @@ def initiate_transfer(db, t_id):
 def execute_transfer(db, t_id, tr):
     try:
         tr.save()
-    except APIError as e:
+    except Exception as e:
         error = repr_exception(e)
         _record_transfer_result(db, t_id, 'failed', error)
         from liberapay.website import website
-        website.tell_sentry(e, {})
+        website.tell_sentry(e, {}, allow_reraise=False)
         raise TransferError(error)
     return record_transfer_result(db, t_id, tr, _raise=True)
 

tests/py/test_currencies.py

@@ -1,6 +1,12 @@
 from __future__ import division, print_function, unicode_literals
 
-from liberapay.testing import EUR, USD, Harness
+from mock import patch
+
+from liberapay.billing.transactions import swap_currencies, Transfer
+from liberapay.exceptions import NegativeBalance, TransferError
+from liberapay.testing import EUR, USD, Harness, Foobar
+from liberapay.testing.mangopay import FakeTransfersHarness, MangopayHarness, fake_transfer
+from liberapay.utils.currencies import MoneyBasket
 
 
 class TestCurrencies(Harness):
@@ -12,3 +18,83 @@ def test_convert(self):
         assert expected == actual
         actual = original.convert(expected.currency)
         assert expected == actual
+
+
+class TestCurrencySwap(FakeTransfersHarness, MangopayHarness):
+
+    @patch('mangopay.resources.TransferRefund.save', autospec=True)
+    def test_swap_currencies(self, TR_save):
+        TR_save.side_effect = fake_transfer
+
+        self.make_exchange('mango-cc', EUR('10.00'), 0, self.janet)
+        self.make_exchange('mango-cc', USD('7.00'), 0, self.homer)
+        start_balances = {
+            'janet': EUR('10.00'),
+            'homer': USD('7.00'),
+            'david': MoneyBasket(),
+        }
+        balances = self.get_balances()
+        assert balances == start_balances
+
+        # Test failure when there isn't enough money in the 1st wallet
+        with self.assertRaises(AssertionError):
+            swap_currencies(self.db, self.janet, self.homer, EUR('100.00'), USD('120.00'))
+        balances = self.get_balances()
+        assert balances == start_balances
+
+        # Test failure when there isn't enough money in the 2nd wallet
+        with self.assertRaises(AssertionError):
+            swap_currencies(self.db, self.janet, self.homer, EUR('10.00'), USD('12.00'))
+        balances = self.get_balances()
+        assert balances == start_balances
+
+        # Test failure of the 1st `prepare_transfer()` call
+        with patch('liberapay.billing.transactions.lock_bundles') as lock_bundles:
+            lock_bundles.side_effect = NegativeBalance
+            with self.assertRaises(NegativeBalance):
+                swap_currencies(self.db, self.janet, self.homer, EUR('3.00'), USD('3.00'))
+        balances = self.get_balances()
+        assert balances == start_balances
+
+        # Test failure of the 2nd `prepare_transfer()` call
+        cash_bundle = self.db.one("SELECT * FROM cash_bundles WHERE owner = %s", (self.homer.id,))
+        self.db.run("UPDATE cash_bundles SET amount = %s WHERE id = %s",
+                    (USD('0.01'), cash_bundle.id))
+        with self.assertRaises(NegativeBalance):
+            swap_currencies(self.db, self.janet, self.homer, EUR('5.00'), USD('6.99'))
+        self.db.run("UPDATE cash_bundles SET amount = %s WHERE id = %s",
+                    (cash_bundle.amount, cash_bundle.id))
+        balances = self.get_balances()
+        assert balances == start_balances
+
+        # Test failure of the 1st `initiate_transfer()` call
+        self.transfer_mock.side_effect = Foobar
+        with self.assertRaises(TransferError):
+            swap_currencies(self.db, self.janet, self.homer, EUR('4.25'), USD('5.55'))
+        balances = self.get_balances()
+        assert balances == start_balances
+
+        # Test failure of the 2nd `initiate_transfer()` call
+        def fail_on_second(tr):
+            if getattr(fail_on_second, 'called', False):
+                raise Foobar
+            fail_on_second.called = True
+            fake_transfer(tr)
+        self.transfer_mock.side_effect = fail_on_second
+        self.db.run("ALTER SEQUENCE transfers_id_seq RESTART WITH 1")
+        with patch('mangopay.resources.Transfer.get') as T_get:
+            T_get.return_value = Transfer(Id=-1, AuthorId=self.janet_id, Tag='1')
+            with self.assertRaises(TransferError):
+                swap_currencies(self.db, self.janet, self.homer, EUR('0.01'), USD('0.01'))
+        balances = self.get_balances()
+        assert balances == start_balances
+
+        # Test success
+        self.transfer_mock.side_effect = fake_transfer
+        swap_currencies(self.db, self.janet, self.homer, EUR('5.00'), USD('6.00'))
+        balances = self.get_balances()
+        assert balances == {
+            'janet': MoneyBasket(EUR('5.00'), USD('6.00')),
+            'homer': MoneyBasket(EUR('5.00'), USD('1.00')),
+            'david': MoneyBasket(),
+        }