From c675c2a51c3a66f416cd2fd2ada1eccec45db2c9 Mon Sep 17 00:00:00 2001
From: gfeun
Date: Thu, 19 Mar 2020 18:35:35 +0100
Subject: perf(demo): improve main cpu loop performance

---
 demo/src/task-scheduler.spec.ts | 52 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 demo/src/task-scheduler.spec.ts

(limited to 'demo/src/task-scheduler.spec.ts')

diff --git a/demo/src/task-scheduler.spec.ts b/demo/src/task-scheduler.spec.ts
new file mode 100644
index 0000000..f5fb4bf
--- /dev/null
+++ b/demo/src/task-scheduler.spec.ts
@@ -0,0 +1,52 @@
+/**
+ * @jest-environment jsdom
+ */
+/// <reference lib="dom" />
+
+import { MicroTaskScheduler } from './task-scheduler';
+
+describe('task-scheduler', () => {
+  let taskScheduler: MicroTaskScheduler;
+  let task: jest.Mock;
+
+  beforeEach(() => {
+    taskScheduler = new MicroTaskScheduler();
+    task = jest.fn();
+  });
+
+  it('should execute task', async () => {
+    taskScheduler.start();
+    taskScheduler.postTask(task);
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    expect(task).toHaveBeenCalledTimes(1);
+  });
+
+  it('should execute task twice when posted twice', async () => {
+    taskScheduler.start();
+    taskScheduler.postTask(task);
+    taskScheduler.postTask(task);
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    expect(task).toHaveBeenCalledTimes(2);
+  });
+
+  it('should not execute task when not started', async () => {
+    taskScheduler.postTask(task);
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    expect(task).not.toHaveBeenCalled();
+  });
+
+  it('should not execute task when stopped', async () => {
+    taskScheduler.start();
+    taskScheduler.stop();
+    taskScheduler.postTask(task);
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    expect(task).not.toHaveBeenCalled();
+  });
+
+  it('should not register listener twice', async () => {
+    const addEventListenerSpy = jest.spyOn(window, 'addEventListener');
+    taskScheduler.start();
+    taskScheduler.start();
+    expect(addEventListenerSpy).toHaveBeenCalledTimes(1);
+  });
+});
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