[REF] utils: move batched from reactivity to utils

tests/reactivity.test.ts

@@ -7,7 +7,8 @@ import {
   useState,
   xml,
 } from "../src";
-import { batched, reactive } from "../src/reactivity";
+import { reactive } from "../src/reactivity";
+import { batched } from "../src/utils";
 import {
   makeDeferred,
   makeTestFixture,

tests/utils.test.ts

@@ -1,4 +1,5 @@
-import { EventBus } from "../src/utils";
+import { batched, EventBus } from "../src/utils";
+import { nextMicroTick } from "./helpers";
 
 describe("event bus behaviour", () => {
   test("can subscribe and be notified", () => {
@@ -33,3 +34,20 @@ describe("event bus behaviour", () => {
     bus.trigger("event", "hello world");
   });
 });
+
+describe("batched", () => {
+  test("callback is called only once after operations", async () => {
+    let n = 0;
+    let fn = batched(() => n++);
+
+    expect(n).toBe(0);
+    fn();
+    fn();
+    expect(n).toBe(0);
+
+    await nextMicroTick();
+    expect(n).toBe(1);
+    await nextMicroTick();
+    expect(n).toBe(1);
+  });
+});