test: mock ResizeObserver for Jest testing environment

Author: aojunhao123

tests/setup.js

@@ -1,3 +1,10 @@
 // jsdom add motion events to test CSSMotion
 window.AnimationEvent = window.AnimationEvent || (() => {});
 window.TransitionEvent = window.TransitionEvent || (() => {});
+global.ResizeObserver = jest.fn(() => {
+    return {
+        observe() { },
+        unobserve() { },
+        disconnect() { },
+    };
+});