fix(testing): apply refactor to test implementation

src/testing.zig

@@ -120,7 +120,8 @@ pub fn expectContainerScreen(size: Point, container: *Container(event.SystemEven
     var renderer: Renderer = .init(allocator, size);
     defer renderer.deinit();
 
-    try container.handle(.{ .size = size });
+    container.reposition(.{});
+    container.resize(size);
     try renderer.render(Container(event.SystemEvent), container);
 
     try expectEqualCells(.{}, renderer.size, expected, renderer.screen);