Fix pool size limit check for unlimited pools (#888)

* Add test case for unlimited pool with minsize 0

* Skip pool limit check for unlimited pools

Author: d-ryzhykau

aiopg/pool.py

@@ -352,7 +352,7 @@ async def _fill_free_pool(self, override_min: bool) -> None:
         if self._free:
             return
 
-        if override_min and self.size < (self.maxsize or 0):
+        if override_min and (not self.maxsize or self.size < self.maxsize):
             self._acquiring += 1
             try:
                 conn = await connect(

tests/test_pool.py

@@ -441,6 +441,13 @@ async def test_unlimited_size(create_pool):
     assert pool._free.maxlen is None
 
 
+async def test_unlimited_size_minsize_0_acquire(create_pool):
+    pool = await create_pool(minsize=0, maxsize=0)
+    async with pool.acquire() as conn:
+        cur = await conn.cursor()
+        await cur.execute("SELECT 1")
+
+
 async def test_connection_closed_after_timeout(create_pool):
     async def sleep(conn):
         cur = await conn.cursor()