Make sure idle never-acquired pool connections are closed due to inactivity

The `max_inactive_connection_lifetime` setting currently fails to apply
to the connection which were never acquired because
`_setup_inactive_callback()` is only called in `release()`.

Fixes: #389

Author: elprans

asyncpg/pool.py

@@ -124,6 +124,8 @@ async def connect(self):
 
         self._con = await self._pool._get_new_connection()
         self._generation = self._pool._generation
+        self._maybe_cancel_inactive_callback()
+        self._setup_inactive_callback()
 
     async def acquire(self) -> PoolConnectionProxy:
         if self._con is None or self._con.is_closed():

tests/test_pool.py

@@ -668,6 +668,24 @@ async def worker(pool):
 
         self.assertGreaterEqual(N, 50)
 
+    async def test_pool_max_inactive_time_05(self):
+        # Test that idle never-acquired connections abide by
+        # the max inactive lifetime.
+        async with self.create_pool(
+                database='postgres', min_size=2, max_size=2,
+                max_inactive_connection_lifetime=0.2) as pool:
+
+            self.assertIsNotNone(pool._holders[0]._con)
+            self.assertIsNotNone(pool._holders[1]._con)
+
+            await pool.execute('SELECT pg_sleep(0.3)')
+            await asyncio.sleep(0.3, loop=self.loop)
+
+            self.assertIs(pool._holders[0]._con, None)
+            # The connection in the second holder was never used,
+            # but should be closed nonetheless.
+            self.assertIs(pool._holders[1]._con, None)
+
     async def test_pool_handles_inactive_connection_errors(self):
         pool = await self.create_pool(database='postgres',
                                       min_size=1, max_size=1)