test: add coverage for None branches in from_session_state

This test ensures the branches where server_capabilities and server_info
are None are covered, achieving 100% branch coverage.

Related: #2111

Author: peter-luminova

tests/client/test_session.py

@@ -829,6 +829,49 @@ async def test_client_session_from_state():
         pass
 
 
+@pytest.mark.anyio
+async def test_client_session_from_state_without_capabilities():
+    """Test that from_session_state() handles None capabilities and server_info."""
+    from mcp.shared.session_state import SessionState
+
+    # Create a session state with None capabilities (before initialization)
+    state = SessionState(
+        session_id="test-session-minimal",
+        protocol_version=LATEST_PROTOCOL_VERSION,
+        next_request_id=0,
+        server_capabilities=None,
+        server_info=None,
+        initialized_sent=False,
+    )
+
+    # Create streams
+    client_to_server_send, client_to_server_receive = anyio.create_memory_object_stream[SessionMessage](1)
+    server_to_client_send, server_to_client_receive = anyio.create_memory_object_stream[SessionMessage](1)
+
+    # Create session from state
+    session = ClientSession.from_session_state(
+        state,
+        server_to_client_receive,
+        client_to_server_send,
+    )
+
+    # Verify the session was created with the correct state
+    assert session._session_id == "test-session-minimal"
+    assert session._request_id == 0
+    assert session._server_capabilities is None
+    assert session._server_info is None
+    assert session._initialized_sent is False
+
+    # Clean up streams
+    async with (
+        client_to_server_send,
+        client_to_server_receive,
+        server_to_client_send,
+        server_to_client_receive,
+    ):
+        pass
+
+
 @pytest.mark.anyio
 async def test_client_session_state_roundtrip():
     """Test that session state can be serialized and restored."""