test: add missing timeout validation tests for pool and cluster

The timeout validation was added to all three classes but tests were
only added for DqliteConnection. Now pool and cluster also have
coverage for the zero-timeout ValueError.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antoineleclair

tests/test_cluster.py

@@ -14,6 +14,11 @@ def test_from_addresses(self) -> None:
         client = ClusterClient.from_addresses(["localhost:9001", "localhost:9002"])
         assert client._timeout == 10.0
 
+    def test_zero_timeout_raises(self) -> None:
+        store = MemoryNodeStore(["localhost:9001"])
+        with pytest.raises(ValueError, match="timeout must be positive"):
+            ClusterClient(store, timeout=0)
+
     async def test_find_leader_no_nodes(self) -> None:
         store = MemoryNodeStore()
         client = ClusterClient(store)

tests/test_pool.py

@@ -22,6 +22,10 @@ def test_zero_max_size_raises(self) -> None:
         with pytest.raises(ValueError, match="max_size.*at least 1"):
             ConnectionPool(["localhost:9001"], max_size=0)
 
+    def test_zero_timeout_raises(self) -> None:
+        with pytest.raises(ValueError, match="timeout must be positive"):
+            ConnectionPool(["localhost:9001"], timeout=0)
+
     def test_init(self) -> None:
         pool = ConnectionPool(
             ["localhost:9001", "localhost:9002"],