test(chapter): [PKG-CHAPTER-05] checkpoint native media timing controls

test/browser/chapter-timing.js

@@ -0,0 +1,56 @@
+export async function installChapterTiming(page, selector) {
+  await page.evaluate((selector) => {
+    const video = selector ? document.querySelector(selector) : window.art.video
+    const records = []
+    let sequence = 0
+    const record = (value) => {
+      if (records.length < 10000)
+        records.push({ at: performance.now(), ...value })
+    }
+    for (const name of ['currentTime', 'duration', 'readyState', 'seeking', 'playbackRate', 'paused']) {
+      const descriptor = Object.getOwnPropertyDescriptor(HTMLMediaElement.prototype, name)
+      if (!descriptor?.get)
+        throw new Error(`Missing native media descriptor: ${name}`)
+      const access = (kind, callback, value) => {
+        const id = sequence++
+        const start = performance.now()
+        record({ id, kind, name, phase: 'before', value })
+        try {
+          const result = callback()
+          record({ id, kind, name, phase: 'after', value: result, elapsed: performance.now() - start })
+          return result
+        }
+        catch (error) {
+          record({ id, kind, name, phase: 'error', error: String(error), elapsed: performance.now() - start })
+          throw error
+        }
+      }
+      Object.defineProperty(video, name, {
+        configurable: true,
+        get() { return access('get', () => descriptor.get.call(this)) },
+        ...(descriptor.set ? { set(value) { access('set', () => descriptor.set.call(this, value), value) } } : {}),
+      })
+    }
+    const events = []
+    for (const name of ['loadstart', 'loadedmetadata', 'loadeddata', 'canplay', 'seeking', 'seeked', 'playing', 'pause', 'error']) {
+      video.addEventListener(name, () => events.push({ name, at: performance.now() }))
+    }
+    const heartbeat = []
+    let previous = performance.now()
+    const timer = setInterval(() => {
+      const at = performance.now()
+      heartbeat.push({ at, gap: at - previous })
+      previous = at
+    }, 100)
+    window.chapterTiming = { records, events, heartbeat, started: previous, timeOrigin: performance.timeOrigin }
+    window.stopChapterTiming = () => clearInterval(timer)
+  }, selector)
+}
+
+export async function readChapterTiming(page, testInfo) {
+  const observation = await page.evaluate(() => {
+    window.stopChapterTiming?.()
+    return window.chapterTiming || null
+  }).catch(error => ({ error: error.message }))
+  await testInfo.attach('chapter-native-access-timing', { contentType: 'application/json', body: JSON.stringify(observation) })
+}