Add video playback observability to Sentry (#11111)

src/lib/media/video/__tests__/playbackTelemetry.test.ts

@@ -0,0 +1,120 @@
+import {createPlaybackTelemetry} from '../playbackTelemetry'
+
+const mockSpan = {
+  setAttribute: jest.fn(),
+  end: jest.fn(),
+}
+
+jest.mock('#/logger/sentry/lib', () => ({
+  Sentry: {
+    startInactiveSpan: jest.fn(() => mockSpan),
+  },
+}))
+
+const {Sentry}: {Sentry: {startInactiveSpan: jest.Mock}} = jest.requireMock(
+  '#/logger/sentry/lib',
+)
+
+describe('createPlaybackTelemetry', () => {
+  beforeEach(() => {
+    jest.clearAllMocks()
+  })
+
+  it('starts a root span on activation with surface and presentation', () => {
+    const telemetry = createPlaybackTelemetry({
+      surface: 'feed',
+      presentation: 'video',
+    })
+    telemetry.activated()
+    expect(Sentry.startInactiveSpan).toHaveBeenCalledWith({
+      name: 'video.playback',
+      op: 'video.playback',
+      attributes: {surface: 'feed', presentation: 'video'},
+    })
+  })
+
+  it('does nothing before activation', () => {
+    const telemetry = createPlaybackTelemetry({
+      surface: 'feed',
+      presentation: 'video',
+    })
+    telemetry.ready()
+    telemetry.playing()
+    telemetry.deactivated()
+    expect(Sentry.startInactiveSpan).not.toHaveBeenCalled()
+    expect(mockSpan.end).not.toHaveBeenCalled()
+  })
+
+  it('ignores duplicate activations while a span is open', () => {
+    const telemetry = createPlaybackTelemetry({
+      surface: 'feed',
+      presentation: 'video',
+    })
+    telemetry.activated()
+    telemetry.activated()
+    expect(Sentry.startInactiveSpan).toHaveBeenCalledTimes(1)
+  })
+
+  it('records ready and playing times once', () => {
+    const telemetry = createPlaybackTelemetry({
+      surface: 'feed',
+      presentation: 'video',
+    })
+    telemetry.activated()
+    telemetry.ready()
+    telemetry.ready()
+    telemetry.playing()
+    telemetry.playing()
+    const calls = mockSpan.setAttribute.mock.calls as [string, unknown][]
+    const attrs = calls.map(c => c[0])
+    expect(attrs.filter(a => a === 'timeToReadyMs')).toHaveLength(1)
+    expect(attrs.filter(a => a === 'timeToFirstPlayMs')).toHaveLength(1)
+  })
+
+  it('ends the span with ok outcome on deactivation, idempotently', () => {
+    const telemetry = createPlaybackTelemetry({
+      surface: 'feed',
+      presentation: 'video',
+    })
+    telemetry.activated()
+    telemetry.deactivated()
+    telemetry.deactivated()
+    expect(mockSpan.setAttribute).toHaveBeenCalledWith('outcome', 'ok')
+    expect(mockSpan.end).toHaveBeenCalledTimes(1)
+  })
+
+  it('ends the span with error outcome and message', () => {
+    const telemetry = createPlaybackTelemetry({
+      surface: 'feed',
+      presentation: 'video',
+    })
+    telemetry.activated()
+    telemetry.error('AVFoundationErrorDomain -11850')
+    expect(mockSpan.setAttribute).toHaveBeenCalledWith(
+      'errorMessage',
+      'AVFoundationErrorDomain -11850',
+    )
+    expect(mockSpan.setAttribute).toHaveBeenCalledWith('outcome', 'error')
+    expect(mockSpan.end).toHaveBeenCalledTimes(1)
+  })
+
+  it('starts a new span for a new activation window', () => {
+    const telemetry = createPlaybackTelemetry({
+      surface: 'immersiveFeed',
+      presentation: 'video',
+    })
+    telemetry.activated({preloaded: true})
+    telemetry.deactivated()
+    telemetry.activated({preloaded: false})
+    expect(Sentry.startInactiveSpan).toHaveBeenCalledTimes(2)
+    expect(Sentry.startInactiveSpan).toHaveBeenLastCalledWith({
+      name: 'video.playback',
+      op: 'video.playback',
+      attributes: {
+        surface: 'immersiveFeed',
+        presentation: 'video',
+        preloaded: false,
+      },
+    })
+  })
+})