step 3: add widget shell sizing and frame pump

tests/test_renderer.py

@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+from dpg_map.commands import CommandKind, MapCommand
+from dpg_map.renderer import drain_renderer_commands
+from dpg_map.state import DirtyFlags, create_map_state
+
+
+def test_renderer_command_drain_preserves_structural_order_and_coalesces() -> None:
+    state = create_map_state(tag="renderer-drain")
+    state.dirty = DirtyFlags.NONE
+
+    state.command_queue.put(MapCommand(CommandKind.ADD_OVERLAY, state.tag, {"tag": "a"}))
+    state.command_queue.put(MapCommand(CommandKind.SET_VIEW, state.tag, {"zoom": 3}))
+    state.command_queue.put(MapCommand(CommandKind.SET_VIEW, state.tag, {"zoom": 4}))
+    state.command_queue.put(MapCommand(CommandKind.UPDATE_OVERLAY, state.tag, {"tag": "a", "v": 1}))
+    state.command_queue.put(MapCommand(CommandKind.UPDATE_OVERLAY, state.tag, {"tag": "a", "v": 2}))
+    state.command_queue.put(MapCommand(CommandKind.DELETE_OVERLAY, state.tag, {"tag": "a"}))
+
+    commands = drain_renderer_commands(state)
+
+    assert [command.kind for command in commands] == [
+        CommandKind.ADD_OVERLAY,
+        CommandKind.SET_VIEW,
+        CommandKind.UPDATE_OVERLAY,
+        CommandKind.DELETE_OVERLAY,
+    ]
+    assert commands[1].payload == {"zoom": 4}
+    assert commands[2].payload == {"tag": "a", "v": 2}
+    assert state.dirty & DirtyFlags.VIEW
+    assert state.dirty & DirtyFlags.OVERLAYS