Add cursor.closed check for rollback operations

Author: Pliner

aiopg/transaction.py

@@ -127,13 +127,15 @@ async def commit(self):
 
     async def rollback(self):
         self._check_commit_rollback()
-        await self._cursor.execute(self._isolation.rollback())
+        if not self._cursor.closed:
+            await self._cursor.execute(self._isolation.rollback())
         self._is_begin = False
 
     async def rollback_savepoint(self):
         self._check_release_rollback()
-        await self._cursor.execute(
-            self._isolation.rollback_savepoint(self._unique_id))
+        if not self._cursor.closed:
+            await self._cursor.execute(
+                self._isolation.rollback_savepoint(self._unique_id))
         self._unique_id = None
 
     async def release_savepoint(self):

tests/test_transaction.py

@@ -1,3 +1,5 @@
+import asyncio
+
 import psycopg2
 import pytest
 
@@ -181,3 +183,61 @@ async def test_transaction_point_oldstyle(engine):
                        (3, 'data')]
 
         await tr.commit()
+
+
+async def test_timeout_in_transaction_context_manager(make_engine):
+    engine = await make_engine(timeout=1)
+    with pytest.raises(asyncio.TimeoutError):
+        async with engine.acquire() as connection:
+            async with Transaction(connection, IsolationLevel.read_committed):
+                await connection.execute("SELECT pg_sleep(10)")
+
+    engine.terminate()
+    await engine.wait_closed()
+
+
+async def test_timeout_in_savepoint_context_manager(make_engine):
+    engine = await make_engine(timeout=1)
+    with pytest.raises(asyncio.TimeoutError):
+        async with engine.acquire() as connection:
+            async with Transaction(
+                connection, IsolationLevel.read_committed
+            ) as transaction:
+                async with transaction.point():
+                    await connection.execute("SELECT pg_sleep(10)")
+
+    engine.terminate()
+    await engine.wait_closed()
+
+
+async def test_cancel_in_transaction_context_manager(engine, loop):
+    with pytest.raises(asyncio.CancelledError):
+        async with engine.acquire() as connection:
+            async with Transaction(connection, IsolationLevel.read_committed):
+                task = loop.create_task(
+                    connection.execute("SELECT pg_sleep(10)"))
+
+                async def cancel_soon():
+                    await asyncio.sleep(1)
+                    task.cancel()
+
+                loop.create_task(cancel_soon())
+                await task
+
+
+async def test_cancel_in_savepoint_context_manager(engine, loop):
+    with pytest.raises(asyncio.CancelledError):
+        async with engine.acquire() as connection:
+            async with Transaction(
+                connection, IsolationLevel.read_committed
+            ) as transaction:
+                async with transaction.point():
+                    task = loop.create_task(
+                        connection.execute("SELECT pg_sleep(10)"))
+
+                    async def cancel_soon():
+                        await asyncio.sleep(1)
+                        task.cancel()
+
+                    loop.create_task(cancel_soon())
+                    await task