Fix Smart Speed playback time contract

test/server/objects/PlaybackSession.test.js

@@ -0,0 +1,26 @@
+const { expect } = require('chai')
+
+const PlaybackSession = require('../../../server/objects/PlaybackSession')
+
+describe('PlaybackSession', () => {
+  it('computes progress from a single currentTime and duration domain', () => {
+    const session = new PlaybackSession({
+      id: 'session-1',
+      userId: 'user-1',
+      libraryItemId: 'item-1',
+      mediaType: 'book',
+      duration: 10,
+      currentTime: 6,
+      startedAt: Date.now(),
+      updatedAt: Date.now(),
+      deviceInfo: {}
+    })
+
+    expect(session.progress).to.equal(0.6)
+    expect(session.mediaProgressObject).to.include({
+      duration: 10,
+      currentTime: 6,
+      progress: 0.6
+    })
+  })
+})