fix and tests (#52)

src/contracting/execution/executor.py

@@ -51,6 +51,8 @@ def execute(self, sender, contract_name, function_name, kwargs,
                 stamp_cost=constants.STAMPS_PER_TAU,
                 metering=None) -> dict:
 
+        current_driver_pending_writes = deepcopy(self.driver.pending_writes)
+
         if not self.bypass_privates:
             assert not function_name.startswith(constants.PRIVATE_METHOD_PREFIX), 'Private method not callable.'
 
@@ -135,6 +137,9 @@ def execute(self, sender, contract_name, function_name, kwargs,
         except Exception as e:
             result = e
             status_code = 1
+
+            # Revert the writes if the transaction fails
+            driver.pending_writes = current_driver_pending_writes
 
             if auto_commit:
                 driver.flush_cache()

tests/integration/test_contracts/exception.py

@@ -0,0 +1,20 @@
+balances = Hash(default_value=0)
+
+@construct
+def seed():
+    balances['stu'] = 999
+    balances['colin'] = 555
+
+@export
+def transfer(amount: int, to: str):
+    sender = ctx.caller
+    assert balances[sender] >= amount, 'Not enough coins to send!'
+
+    balances[sender] -= amount
+    balances[to] += amount
+
+    raise Exception('This is an exception')
+
+@export
+def balance_of(account: str):
+    return balances[account]

tests/unit/test_revert_on_exception.py

@@ -0,0 +1,101 @@
+import unittest
+from contracting.storage.driver import Driver
+from contracting.execution.executor import Executor
+from contracting.constants import STAMPS_PER_TAU
+from xian.processor import TxProcessor
+from contracting.client import ContractingClient
+import contracting
+import random
+import string
+import os
+import sys
+from loguru import logger
+
+# Get the directory where the script is located
+script_dir = os.path.dirname(os.path.abspath(sys.argv[0]))
+
+# Change the current working directory
+os.chdir(script_dir)
+
+def submission_kwargs_for_file(f):
+    # Get the file name only by splitting off directories
+    split = f.split('/')
+    split = split[-1]
+
+    # Now split off the .s
+    split = split.split('.')
+    contract_name = split[0]
+
+    with open(f) as file:
+        contract_code = file.read()
+
+    return {
+        'name': f'con_{contract_name}',
+        'code': contract_code,
+    }
+
+TEST_SUBMISSION_KWARGS = {
+    'sender': 'stu',
+    'contract_name': 'submission',
+    'function_name': 'submit_contract'
+}
+
+class MyTestCase(unittest.TestCase):
+
+    def setUp(self):
+        self.c = ContractingClient()
+        self.tx_processor = TxProcessor(client=self.c)
+        # Hard load the submission contract
+        self.d = self.c.raw_driver
+        self.d.flush_full()
+
+        with open(contracting.__path__[0] + '/contracts/submission.s.py') as f:
+            contract = f.read()
+
+        self.d.set_contract(name='submission', code=contract)
+
+        with open('../integration/test_contracts/currency.s.py') as f:
+            contract = f.read()
+        self.d.set_contract(name='currency', code=contract)
+
+        self.c.executor.execute(**TEST_SUBMISSION_KWARGS, kwargs=submission_kwargs_for_file('../integration/test_contracts/currency.s.py'), metering=False, auto_commit=True)
+
+        self.c.executor.execute(**TEST_SUBMISSION_KWARGS,
+                       kwargs=submission_kwargs_for_file('../integration/test_contracts/exception.py'), 
+                       metering=False, auto_commit=True)
+        self.d.commit()
+
+    def test_exception(self):
+        prior_balance = self.d.get('con_exception.balances:stu')
+        logger.debug(f"Prior balance (exception): {prior_balance}")
+
+
+        output = self.tx_processor.process_tx({
+            "payload":
+            {'sender': 'stu', 'contract': 'con_exception', 'function': 'transfer', 'kwargs': {'amount': 100, 'to': 'colin'},"stamps_supplied":1000},
+            "metadata":
+            {"signature":"abc"},"b_meta":{"nanos":0,
+            "hash":"0x0","height":0}})
+        logger.debug(f"Output (exception): {output}")
+
+        new_balance = self.d.get('con_exception.balances:stu')
+        logger.debug(f"New balance (exception): {new_balance}")
+
+        self.assertEqual(prior_balance, new_balance)
+
+    def test_non_exception(self):
+        prior_balance = self.d.get('con_currency.balances:stu')
+
+        output = self.tx_processor.process_tx({
+            "payload":
+            {'sender': 'stu', 'contract': 'con_currency', 'function': 'transfer', 'kwargs': {'amount': 100, 'to': 'colin'},"stamps_supplied":1000},
+            "metadata":
+            {"signature":"abc"},"b_meta":{"nanos":0,"hash":"0x0","height":0}})
+
+        new_balance = self.d.get('con_currency.balances:stu')
+        logger.debug(f"New balance (non-exception): {new_balance}")
+
+        self.assertEqual(prior_balance - 100, new_balance)
+
+if __name__ == '__main__':
+    unittest.main()