diff --git a/test/cast/cast_receiver_integration.js b/test/cast/cast_receiver_integration.js
index dd6ed3c4e..b1f41ebd6 100644
--- a/test/cast/cast_receiver_integration.js
+++ b/test/cast/cast_receiver_integration.js
@@ -329,8 +329,8 @@ filterDescribe('CastReceiver', castReceiverIntegrationSupport, () => {
   }
 
   /**
-   * @param {?} message
-   * @param {!Object} bus
+   * @param {*} message
+   * @param {!cast.receiver.CastMessageBus} bus
    * @param {string=} senderId
    */
   function fakeIncomingMessage(message, bus, senderId) {
diff --git a/test/cast/cast_receiver_unit.js b/test/cast/cast_receiver_unit.js
index 2493c76d0..5bb45ff8a 100644
--- a/test/cast/cast_receiver_unit.js
+++ b/test/cast/cast_receiver_unit.js
@@ -271,6 +271,8 @@ filterDescribe('CastReceiver', castReceiverSupport, () => {
           mockVideo, mockPlayer, Util.spyFunc(mockAppDataCallback));
 
       fakeInitState = {
+        manifest: null,
+        startTime: null,
         player: {
           configure: fakeConfig,
         },
@@ -307,7 +309,7 @@ filterDescribe('CastReceiver', castReceiverSupport, () => {
       // The rest is done async:
       await shaka.test.Util.shortDelay();
       expect(mockPlayer.setTextTrackVisibility).toHaveBeenCalledWith(
-          fakeInitState['playerAfterLoad'].setTextTrackVisibility);
+          fakeInitState.playerAfterLoad.setTextTrackVisibility);
       expect(mockVideo.loop).toBe(fakeInitState.video.loop);
       expect(mockVideo.playbackRate).toBe(fakeInitState.video.playbackRate);
     });
@@ -418,7 +420,7 @@ filterDescribe('CastReceiver', castReceiverSupport, () => {
 
       // State was still transferred, though:
       expect(mockPlayer.setTextTrackVisibility).toHaveBeenCalledWith(
-          fakeInitState['playerAfterLoad'].setTextTrackVisibility);
+          fakeInitState.playerAfterLoad.setTextTrackVisibility);
       expect(mockVideo.loop).toBe(fakeInitState.video.loop);
       expect(mockVideo.playbackRate).toBe(fakeInitState.video.playbackRate);
     });
@@ -988,8 +990,8 @@ filterDescribe('CastReceiver', castReceiverSupport, () => {
   }
 
   /**
-   * @param {?} message
-   * @param {!Object} bus
+   * @param {*} message
+   * @param {!cast.receiver.CastMessageBus} bus
    * @param {string=} senderId
    */
   function fakeIncomingMessage(message, bus, senderId) {
diff --git a/test/hls/hls_parser_unit.js b/test/hls/hls_parser_unit.js
index 7bc89adac..9beca24b1 100644
--- a/test/hls/hls_parser_unit.js
+++ b/test/hls/hls_parser_unit.js
@@ -2061,7 +2061,7 @@ describe('HlsParser', () => {
       // We are assuming that the time will be pulled out of the main mp4
       // segment, so if we see a request that has a range header, we will stop
       // the parser.
-      /** @type {!Map.<string, !ArrayBuffer>} */
+      /** @type {!Map.<string, !BufferSource>} */
       const responses = new Map();
       responses.set('test:/main.mp4', segmentData);
       responses.set('test:/init.mp4', initSegmentData);
diff --git a/test/media/drm_engine_unit.js b/test/media/drm_engine_unit.js
index bfb4d6d5b..5648c91bd 100644
--- a/test/media/drm_engine_unit.js
+++ b/test/media/drm_engine_unit.js
@@ -758,8 +758,9 @@ describe('DrmEngine', () => {
       expect(session.generateRequest)
           .toHaveBeenCalledWith('keyids', jasmine.any(Uint8Array));
 
-      const initData = JSON.parse(shaka.util.StringUtils.fromUTF8(
-          session.generateRequest.calls.argsFor(0)[1]));
+      const initData = /** @type {{kids: !Array.<string>}} */(JSON.parse(
+          shaka.util.StringUtils.fromUTF8(
+              session.generateRequest.calls.argsFor(0)[1])));
       const keyId1 = Uint8ArrayUtils.toHex(
           Uint8ArrayUtils.fromBase64(initData.kids[0]));
       const keyId2 = Uint8ArrayUtils.toHex(
diff --git a/test/media/media_source_engine_unit.js b/test/media/media_source_engine_unit.js
index 35bd748f2..77c85105d 100644
--- a/test/media/media_source_engine_unit.js
+++ b/test/media/media_source_engine_unit.js
@@ -1183,7 +1183,7 @@ describe('MediaSourceEngine', () => {
 
   function createMockTextEngineCtor() {
     const ctor = jasmine.createSpy('TextEngine');
-    ctor.isTypeSupported = () => true;
+    ctor['isTypeSupported'] = () => true;
     ctor.and.callFake(() => {
       expect(mockTextEngine).toBeFalsy();
       mockTextEngine = jasmine.createSpyObj('TextEngine', [
diff --git a/test/media/playhead_unit.js b/test/media/playhead_unit.js
index d9f730597..de9e989d6 100644
--- a/test/media/playhead_unit.js
+++ b/test/media/playhead_unit.js
@@ -58,7 +58,8 @@ let PlayingTestInfo;
  *   seekTo: number,
  *   expectedEndTime: number,
  *   expectEvent: boolean,
- *   jumpLargeGaps: (boolean|undefined)
+ *   jumpLargeGaps: (boolean|undefined),
+ *   preventDefault: (boolean|undefined)
  * }}
  *
  * @description
@@ -83,6 +84,8 @@ let PlayingTestInfo;
  *   If true, expect the 'largegap' event to be fired.
  * @property {(boolean|undefined)} jumpLargeGaps
  *   If given, set this field of the Playhead configuration.
+ * @property {(boolean|undefined)} preventDefault
+ *   If true, call preventDefault() on the 'largegap' event.
  */
 let SeekTestInfo;
 
diff --git a/test/offline/offline_integration.js b/test/offline/offline_integration.js
index af86d9b22..aed5cdc05 100644
--- a/test/offline/offline_integration.js
+++ b/test/offline/offline_integration.js
@@ -58,9 +58,9 @@ filterDescribe('Offline', supportsStorage, () => {
 
     const contentUri = content.offlineUri;
     goog.asserts.assert(
-        contentUri, 'Stored content should have an offline uri.');
+        contentUri != null, 'Stored content should have an offline uri.');
 
-    await player.load(content.offlineUri);
+    await player.load(contentUri);
 
     video.play();
     await playTo(/* end= */ 3, /* timeout= */ 10);
diff --git a/test/offline/storage_integration.js b/test/offline/storage_integration.js
index 1144deb90..97906a87a 100644
--- a/test/offline/storage_integration.js
+++ b/test/offline/storage_integration.js
@@ -16,7 +16,7 @@ async function drmStorageSupport() {
 
   const support = await shaka.Player.probeSupport();
   const widevineSupport = support.drm['com.widevine.alpha'];
-  return widevineSupport && widevineSupport.persistentState;
+  return !!(widevineSupport && widevineSupport.persistentState);
 }
 
 filterDescribe('Storage', storageSupport, () => {
diff --git a/test/player_unit.js b/test/player_unit.js
index a7b48e47a..454cd5c2b 100644
--- a/test/player_unit.js
+++ b/test/player_unit.js
@@ -734,14 +734,14 @@ describe('Player', () => {
     it('does not pollute other advanced DRM configs', () => {
       player.configure('drm.advanced.foo', {});
       player.configure('drm.advanced.bar', {});
-      const fooConfig1 = player.getConfiguration().drm.advanced.foo;
-      const barConfig1 = player.getConfiguration().drm.advanced.bar;
+      const fooConfig1 = player.getConfiguration().drm.advanced['foo'];
+      const barConfig1 = player.getConfiguration().drm.advanced['bar'];
       expect(fooConfig1.distinctiveIdentifierRequired).toBe(false);
       expect(barConfig1.distinctiveIdentifierRequired).toBe(false);
 
       player.configure('drm.advanced.foo.distinctiveIdentifierRequired', true);
-      const fooConfig2 = player.getConfiguration().drm.advanced.foo;
-      const barConfig2 = player.getConfiguration().drm.advanced.bar;
+      const fooConfig2 = player.getConfiguration().drm.advanced['foo'];
+      const barConfig2 = player.getConfiguration().drm.advanced['bar'];
       expect(fooConfig2.distinctiveIdentifierRequired).toBe(true);
       expect(barConfig2.distinctiveIdentifierRequired).toBe(false);
     });
@@ -1585,7 +1585,7 @@ describe('Player', () => {
       // choices are limited only by channel count and key status.
       for (const variant of manifest.variants) {
         const keyId = (variant.audio.id % 2) ? 'aaa' : 'bbb';
-        variant.audio.keyId = keyId;
+        variant.audio.keyIds = new Set([keyId]);
         variant.video.roles = [];
         variant.audio.roles = [];
       }
diff --git a/test/routing/walker_unit.js b/test/routing/walker_unit.js
index ab450238c..c8a49e6b1 100644
--- a/test/routing/walker_unit.js
+++ b/test/routing/walker_unit.js
@@ -289,11 +289,11 @@ describe('Walker', () => {
     const goToC = startNewRoute(nodeC, /* interruptible= */ false);
     const goToB = startNewRoute(nodeB, /* interruptible= */ true);
 
-    /** @type {jasmine.Spy} */
+    /** @type {!jasmine.Spy} */
     const canceledCSpy = jasmine.createSpy('cancel c');
     goToC.onCancel = shaka.test.Util.spyFunc(canceledCSpy);
 
-    /** @type {jasmine.Spy} */
+    /** @type {!jasmine.Spy} */
     const canceledBSpy = jasmine.createSpy('cancel b');
     goToB.onCancel = shaka.test.Util.spyFunc(canceledBSpy);
 
diff --git a/test/test/externs/jasmine.js b/test/test/externs/jasmine.js
index 14d8b8235..323ef9c83 100644
--- a/test/test/externs/jasmine.js
+++ b/test/test/externs/jasmine.js
@@ -223,7 +223,7 @@ jasmine.SpyStrategy = function() {};
 
 /**
  * @param {...*} varArgs
- * @return {*}
+ * @return {?}
  */
 jasmine.SpyStrategy.prototype.exec = function(varArgs) {};
 
@@ -271,15 +271,15 @@ jasmine.SpyStrategy.prototype.stub = function() {};
 jasmine.CallContext = function() {};
 
 
-/** @const {*} */
+/** @const {?} */
 jasmine.CallContext.prototype.object;
 
 
-/** @const {!Array.<*>} */
+/** @const {!Array.<?>} */
 jasmine.CallContext.prototype.args;
 
 
-/** @const {*} */
+/** @const {?} */
 jasmine.CallContext.prototype.returnValue;
 
 
@@ -300,12 +300,12 @@ jasmine.CallTracker.prototype.count = function() {};
 
 /**
  * @param {number} i
- * @return {!Array.<*>}
+ * @return {!Array.<?>}
  */
 jasmine.CallTracker.prototype.argsFor = function(i) {};
 
 
-/** @return {!Array.<!Array.<*>>} */
+/** @return {!Array.<!Array.<?>>} */
 jasmine.CallTracker.prototype.allArgs = function() {};
 
 
@@ -375,9 +375,13 @@ jasmine.any = function(factory) {};
 jasmine.anything = function() {};
 
 
+/** @typedef {{ sample: ? }} */
+jasmine.ObjectContainingType;
+
+
 /**
  * @param {!Object} value
- * @return {!Object}
+ * @return {jasmine.ObjectContainingType}
  */
 jasmine.objectContaining = function(value) {};
 
diff --git a/test/test/util/canned_idb.js b/test/test/util/canned_idb.js
index 59f8a8533..cebec087d 100644
--- a/test/test/util/canned_idb.js
+++ b/test/test/util/canned_idb.js
@@ -29,7 +29,7 @@ shaka.test.CannedIDB = class {
   static async dumpJSON(name, dummyArrayBuffers) {
     const savedDatabase = await this.dump(name);
     const replacer =
-        (key, value) => this.replacer_(dummyArrayBuffers, key, value);
+        (key, value) => this.replacer_(dummyArrayBuffers || false, key, value);
     return JSON.stringify(savedDatabase, replacer);
   }
 
@@ -72,7 +72,9 @@ shaka.test.CannedIDB = class {
    * @return {!Promise} Resolved when the operation is complete.
    */
   static async restoreJSON(name, savedDatabaseJson, wipeDatabase) {
-    const savedDatabase = JSON.parse(savedDatabaseJson, this.reviver_);
+    const savedDatabase =
+      /** @type {shaka.test.CannedIDB.SavedDatabase} */(JSON.parse(
+          savedDatabaseJson, this.reviver_));
     await this.restore(name, savedDatabase, wipeDatabase);
   }
 
@@ -153,7 +155,7 @@ shaka.test.CannedIDB = class {
 
   /**
    * @param {string} name The name of the database to open.
-   * @return {!Promise.<IDBDatabase>} Resolved when the named DB has been
+   * @return {!Promise.<!IDBDatabase>} Resolved when the named DB has been
    *   opened.
    * @private
    */
diff --git a/test/test/util/jasmine_fetch.js b/test/test/util/jasmine_fetch.js
index 0526a67c4..23b29c88c 100644
--- a/test/test/util/jasmine_fetch.js
+++ b/test/test/util/jasmine_fetch.js
@@ -57,11 +57,11 @@ jasmine.Fetch = class {
    * @private
    */
   static makeAbortError_() {
-    // As per the spec, this should be a DOMException, but
-    // there is not a public constructor for this
+    // According to the spec, this should be a DOMException, but there is not a
+    // public constructor for that.  So we make this look-alike instead.
     const exception = new Error('The operation was aborted. ');
     exception.name = 'AbortError';
-    exception.code = 20;
+    exception['code'] = DOMException['ABORT_ERR'];
     return exception;
   }
 
@@ -211,13 +211,13 @@ jasmine.Fetch.requests = class {
 };
 
 jasmine.Fetch.ReadableStream = class {
-  /** @param {!Object} underlyingSource */
+  /** @param {!ReadableStreamSource} underlyingSource */
   constructor(underlyingSource) {
-    const noop = () => {};
-    const controller = {
-      close: noop,
-      enqueue: noop,
-    };
+    const controller = /** @type {!ReadableByteStreamController} */({
+      close: () => {},
+      enqueue: (chunk) => {},
+      error: (err) => {},
+    });
     underlyingSource.start(controller);
   }
 };
diff --git a/test/test/util/ui_utils.js b/test/test/util/ui_utils.js
index ccdea0339..694b02053 100644
--- a/test/test/util/ui_utils.js
+++ b/test/test/util/ui_utils.js
@@ -19,7 +19,9 @@ shaka.test.UiUtils = class {
     // Create UI
     config = config || {};
     const ui = new shaka.ui.Overlay(player, videoContainer, video);
-    ui.getControls().addEventListener('error', (/** * */ e) => fail(e.detail));
+    // TODO: generate externs automatically from @event types
+    // This event should be a shaka.Player.ErrorEvent
+    ui.getControls().addEventListener('error', (e) => fail(e['detail']));
     ui.configure(config);
     return ui;
   }
@@ -126,7 +128,7 @@ shaka.test.UiUtils = class {
 
 
   /**
-   * @param {!Element} cssLink
+   * @param {!HTMLLinkElement} cssLink
    */
   static async setupCSS(cssLink) {
     const head = document.head;
diff --git a/test/test/util/util.js b/test/test/util/util.js
index 28e11910d..3ded25c6a 100644
--- a/test/test/util/util.js
+++ b/test/test/util/util.js
@@ -20,13 +20,14 @@ shaka.test.StatusPromise = class {
     this.status;
 
     // TODO: investigate using expectAsync() for this when possible.
-    p.status = 'pending';
-    p.then(() => {
-      p.status = 'resolved';
+    const p2 = /** @type {!shaka.test.StatusPromise} */(p);
+    p2.status = 'pending';
+    p2.then(() => {
+      p2.status = 'resolved';
     }, () => {
-      p.status = 'rejected';
+      p2.status = 'rejected';
     });
-    return /** @type {!shaka.test.StatusPromise} */(p);
+    return p2;
   }
 };
 
@@ -104,7 +105,7 @@ shaka.test.Util = class {
 
   /**
    * @param {!shaka.util.Error} error
-   * @return {!Object}
+   * @return {jasmine.ObjectContainingType}
    */
   static jasmineError(error) {
     // NOTE: Safari will add extra properties to any thrown object, and some of
@@ -213,8 +214,10 @@ shaka.test.Util = class {
     const isInit = first instanceof shaka.media.InitSegmentReference &&
         second instanceof shaka.media.InitSegmentReference;
     if (isSegment || isInit) {
-      const a = first.getUris();
-      const b = second.getUris();
+      const firstRef = /** @type {shaka.media.AnySegmentReference} */(first);
+      const secondRef = /** @type {shaka.media.AnySegmentReference} */(second);
+      const a = firstRef.getUris();
+      const b = secondRef.getUris();
       if (typeof a !== 'object' || typeof b !== 'object' ||
           typeof a.length != 'number' || typeof b.length !== 'number') {
         return false;
@@ -225,10 +228,10 @@ shaka.test.Util = class {
       }
 
       // Make shallow copies of each, without their getUris fields.
-      const trimmedFirst = Object.assign({}, /** @type {Object} */(first));
-      delete trimmedFirst.getUris;
-      const trimmedSecond = Object.assign({}, /** @type {Object} */(second));
-      delete trimmedSecond.getUris;
+      const trimmedFirst = Object.assign({}, /** @type {Object} */(firstRef));
+      delete trimmedFirst['getUris'];
+      const trimmedSecond = Object.assign({}, /** @type {Object} */(secondRef));
+      delete trimmedSecond['getUris'];
 
       // Compare those using Jasmine's utility, which will compare the fields of
       // an object and the items of an array.
diff --git a/test/ui/ad_ui_unit.js b/test/ui/ad_ui_unit.js
index 634746a3e..67cc36f70 100644
--- a/test/ui/ad_ui_unit.js
+++ b/test/ui/ad_ui_unit.js
@@ -5,7 +5,7 @@
 
 describe('Ad UI', () => {
   const UiUtils = shaka.test.UiUtils;
-  /** @type {!Element} */
+  /** @type {!HTMLLinkElement} */
   let cssLink;
   /** @type {!HTMLElement} */
   let container;
@@ -19,7 +19,7 @@ describe('Ad UI', () => {
 
   beforeAll(async () => {
     // Add css file
-    cssLink = document.createElement('link');
+    cssLink = /** @type {!HTMLLinkElement} */(document.createElement('link'));
     await UiUtils.setupCSS(cssLink);
     shaka.Player.setAdManagerFactory(() => new shaka.test.FakeAdManager());
   });
diff --git a/test/ui/text_displayer_unit.js b/test/ui/text_displayer_unit.js
index 9e61b94fe..6468ff2dc 100644
--- a/test/ui/text_displayer_unit.js
+++ b/test/ui/text_displayer_unit.js
@@ -23,7 +23,7 @@ describe('UITextDisplayer', () => {
    *   font-size: '10px',
    * }
    * @param {string} cssStr
-   * @return {Object.<string, string|number>}
+   * @return {!Object.<string, string|number>}
    */
   function parseCssText(cssStr) {
     // Remove the white spaces in the string.
diff --git a/test/ui/ui_customization_unit.js b/test/ui/ui_customization_unit.js
index d80c06bce..e373d294b 100644
--- a/test/ui/ui_customization_unit.js
+++ b/test/ui/ui_customization_unit.js
@@ -5,7 +5,7 @@
 
 describe('UI Customization', () => {
   const UiUtils = shaka.test.UiUtils;
-  /** @type {!Element} */
+  /** @type {!HTMLLinkElement} */
   let cssLink;
   /** @type {!HTMLElement} */
   let container;
@@ -14,7 +14,7 @@ describe('UI Customization', () => {
 
   beforeAll(async () => {
     // Add css file
-    cssLink = document.createElement('link');
+    cssLink = /** @type {!HTMLLinkElement} */(document.createElement('link'));
     await UiUtils.setupCSS(cssLink);
   });
 
diff --git a/test/ui/ui_integration.js b/test/ui/ui_integration.js
index 96387f5bc..dd1d6dd64 100644
--- a/test/ui/ui_integration.js
+++ b/test/ui/ui_integration.js
@@ -20,7 +20,7 @@ describe('UI', () => {
   let eventManager;
   /** @type {shaka.test.Waiter} */
   let waiter;
-  /** @type {!Element} */
+  /** @type {!HTMLLinkElement} */
   let cssLink;
   /** @type {!shaka.ui.Controls} */
   let controls;
@@ -28,7 +28,7 @@ describe('UI', () => {
   let compiledShaka;
 
   beforeAll(async () => {
-    cssLink = document.createElement('link');
+    cssLink = /** @type {!HTMLLinkElement} */(document.createElement('link'));
     await UiUtils.setupCSS(cssLink);
 
     compiledShaka = await Util.loadShaka(getClientArg('uncompiled'));
@@ -72,7 +72,9 @@ describe('UI', () => {
     eventManager = new shaka.util.EventManager();
     waiter = new shaka.test.Waiter(eventManager);
 
-    controls = ui.getControls();
+    const tempControls = ui.getControls();
+    goog.asserts.assert(tempControls != null, 'Controls are null!');
+    controls = tempControls;
 
     onErrorSpy = jasmine.createSpy('onError');
     onErrorSpy.and.callFake((event) => {
diff --git a/test/ui/ui_unit.js b/test/ui/ui_unit.js
index c8ce300e6..a513ee19b 100644
--- a/test/ui/ui_unit.js
+++ b/test/ui/ui_unit.js
@@ -11,12 +11,12 @@ describe('UI', () => {
 
   /** @type {shaka.Player} */
   let player;
-  /** @type {!Element} */
+  /** @type {!HTMLLinkElement} */
   let cssLink;
 
   beforeAll(async () => {
     // Add css file
-    cssLink = document.createElement('link');
+    cssLink = /** @type {!HTMLLinkElement} */(document.createElement('link'));
     await UiUtils.setupCSS(cssLink);
   });