1 files changed, 116 insertions, 0 deletions
diff --git a/dom/media/mediacontrol/tests/browser/browser_media_control_playback_state.js b/dom/media/mediacontrol/tests/browser/browser_media_control_playback_state.js
new file mode 100644
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+++ b/dom/media/mediacontrol/tests/browser/browser_media_control_playback_state.js
@@ -0,0 +1,116 @@
+const PAGE_NON_AUTOPLAY =
+  "https://example.com/browser/dom/media/mediacontrol/tests/browser/file_non_autoplay.html";
+
+const testVideoId = "video";
+
+add_task(async function setupTestingPref() {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["media.mediacontrol.testingevents.enabled", true],
+      ["dom.media.mediasession.enabled", true],
+    ],
+  });
+});
+
+/**
+ * This test is used to check the actual playback state [1] of the main media
+ * controller. The declared playback state is the playback state from the active
+ * media session, and the guessed playback state is determined by the media's
+ * playback state. Both the declared playback and the guessed playback state
+ * would be used to decide the final result of the actual playback state.
+ *
+ * [1] https://w3c.github.io/mediasession/#actual-playback-state
+ */
+add_task(async function testDefaultPlaybackStateBeforeAnyMediaStart() {
+  info(`open media page`);
+  const tab = await createLoadedTabWrapper(PAGE_NON_AUTOPLAY, {
+    needCheck: false,
+  });
+
+  info(`before media starts, playback state should be 'none'`);
+  await isActualPlaybackStateEqualTo(tab, "none");
+
+  info(`remove tab`);
+  await tab.close();
+});
+
+add_task(async function testGuessedPlaybackState() {
+  info(`open media page`);
+  const tab = await createLoadedTabWrapper(PAGE_NON_AUTOPLAY);
+
+  info(
+    `Now declared='none', guessed='playing', so actual playback state should be 'playing'`
+  );
+  await setGuessedPlaybackState(tab, "playing");
+  await isActualPlaybackStateEqualTo(tab, "playing");
+
+  info(
+    `Now declared='none', guessed='paused', so actual playback state should be 'paused'`
+  );
+  await setGuessedPlaybackState(tab, "paused");
+  await isActualPlaybackStateEqualTo(tab, "paused");
+
+  info(`remove tab`);
+  await tab.close();
+});
+
+add_task(async function testBothGuessedAndDeclaredPlaybackState() {
+  info(`open media page`);
+  const tab = await createLoadedTabWrapper(PAGE_NON_AUTOPLAY);
+
+  info(
+    `Now declared='paused', guessed='playing', so actual playback state should be 'playing'`
+  );
+  await setDeclaredPlaybackState(tab, "paused");
+  await setGuessedPlaybackState(tab, "playing");
+  await isActualPlaybackStateEqualTo(tab, "playing");
+
+  info(
+    `Now declared='paused', guessed='paused', so actual playback state should be 'paused'`
+  );
+  await setGuessedPlaybackState(tab, "paused");
+  await isActualPlaybackStateEqualTo(tab, "paused");
+
+  info(
+    `Now declared='playing', guessed='paused', so actual playback state should be 'playing'`
+  );
+  await setDeclaredPlaybackState(tab, "playing");
+  await isActualPlaybackStateEqualTo(tab, "playing");
+
+  info(`remove tab`);
+  await tab.close();
+});
+
+/**
+ * The following are helper functions.
+ */
+function setGuessedPlaybackState(tab, state) {
+  if (state == "playing") {
+    return playMedia(tab, testVideoId);
+  } else if (state == "paused") {
+    return pauseMedia(tab, testVideoId);
+  }
+  // We won't set the state `stopped`, which would only happen if no any media
+  // has ever been started in the page.
+  ok(false, `should only set 'playing' or 'paused' state`);
+  return Promise.resolve();
+}
+
+async function isActualPlaybackStateEqualTo(tab, expectedState) {
+  const controller = tab.linkedBrowser.browsingContext.mediaController;
+  if (controller.playbackState != expectedState) {
+    await new Promise(r => (controller.onplaybackstatechange = r));
+  }
+  is(
+    controller.playbackState,
+    expectedState,
+    `current state '${controller.playbackState}' is equal to '${expectedState}'`
+  );
+}
+
+function setDeclaredPlaybackState(tab, state) {
+  return SpecialPowers.spawn(tab.linkedBrowser, [state], playbackState => {
+    info(`set declared playback state to '${playbackState}'`);
+    content.navigator.mediaSession.playbackState = playbackState;
+  });
+}