diff --git a/test/test/util/fake_drm_engine.js b/test/test/util/fake_drm_engine.js
new file mode 100644
index 0000000000..84373fc4f1
--- /dev/null
+++ b/test/test/util/fake_drm_engine.js
@@ -0,0 +1,106 @@
+/**
+ * @license
+ * Copyright 2016 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+goog.provide('shaka.test.FakeDrmEngine');
+
+
+/**
+ * A fake DrmEngine.
+ *
+ * @extends {shaka.media.DrmEngine}
+ */
+shaka.test.FakeDrmEngine = class {
+  constructor() {
+    /** @private {!Array.<number>} */
+    this.offlineSessions_ = [];
+    /** @private {?shaka.extern.DrmInfo} */
+    this.drmInfo_ = null;
+
+    const resolved = Promise.resolve();
+
+    /** @type {!jasmine.Spy} */
+    this.attach = jasmine.createSpy('attach');
+    this.attach.and.returnValue(resolved);
+
+    /** @type {!jasmine.Spy} */
+    this.configure = jasmine.createSpy('configure');
+
+    // Because of the |IDestroyable| interface, we need to cast destroy to be
+    // a function so that closure will understand that FakeDrmEngine still meets
+    // the interface requirements.
+    /** @type {!jasmine.Spy} */
+    const destroySpy = jasmine.createSpy('destroy');
+    destroySpy.and.returnValue(resolved);
+    this.destroy = shaka.test.Util.spyFunc(destroySpy);
+
+    /** @type {!jasmine.Spy} */
+    this.getDrmInfo = jasmine.createSpy('getDrmInfo');
+    // We use |callFake| to ensure that updated values of |this.drmInfo_| will
+    // be returned.
+    this.getDrmInfo.and.callFake(() => this.drmInfo_);
+
+    /** @type {!jasmine.Spy} */
+    this.getExpiration = jasmine.createSpy('getExpiration');
+    this.getExpiration.and.returnValue(Infinity);
+
+    /** @type {!jasmine.Spy} */
+    this.getKeyStatuses = jasmine.createSpy('getKeyStatuses');
+    this.getKeyStatuses.and.returnValue({});
+
+    /** @type {!jasmine.Spy} */
+    this.getSessionIds = jasmine.createSpy('getSessionIds');
+    this.getSessionIds.and.callFake(() => this.offlineSessions_);
+
+    /**
+     * See |shaka.test.ManifestGenerator.protototype.createStream|.
+     * @type {!jasmine.Spy}
+     */
+    this.getSupportedTypes = jasmine.createSpy('getSupportedTypes');
+    this.getSupportedTypes.and.returnValue(['video/mp4; codecs="avc1.4d401f"']);
+
+    /** @type {!jasmine.Spy} */
+    this.init = jasmine.createSpy('init');
+    this.init.and.returnValue(resolved);
+
+    /** @type {!jasmine.Spy} */
+    this.initialized = jasmine.createSpy('initialized');
+    this.initialized.and.returnValue(true);
+
+    /** @type {!jasmine.Spy} */
+    this.isSupportedByKeySystem = jasmine.createSpy('isSupportedByKeySystem');
+    this.isSupportedByKeySystem.and.returnValue(true);
+
+    /** @type {!jasmine.Spy} */
+    this.keySystem = jasmine.createSpy('keySystem');
+    this.keySystem.and.returnValue('com.example.fake');
+  }
+
+  /**
+   * @param {shaka.extern.DrmInfo} info
+   */
+  setDrmInfo(info) {
+    this.drmInfo_ = info;
+  }
+
+  /**
+   * @param {!Array.<number>} sessions
+   */
+  setSessionIds(sessions) {
+    // Copy the values to break the reference to the input value.
+    this.offlineSessions_ = sessions.map((s) => s);
+  }
+};
diff --git a/test/test/util/simple_fakes.js b/test/test/util/simple_fakes.js
index 8448477237..c7e09cbfdd 100644
--- a/test/test/util/simple_fakes.js
+++ b/test/test/util/simple_fakes.js
@@ -16,7 +16,6 @@
  */
 
 goog.provide('shaka.test.FakeAbrManager');
-goog.provide('shaka.test.FakeDrmEngine');
 goog.provide('shaka.test.FakeManifestParser');
 goog.provide('shaka.test.FakePlayhead');
 goog.provide('shaka.test.FakePlayheadObserver');
@@ -113,69 +112,6 @@ shaka.test.FakeAbrManager.prototype.setVariants;
 shaka.test.FakeAbrManager.prototype.configure;
 
 
-/**
- * A fake DrmEngine.
- *
- * @constructor
- * @struct
- * @extends {shaka.media.DrmEngine}
- * @return {!Object}
- */
-shaka.test.FakeDrmEngine = function() {
-  let resolve = Promise.resolve.bind(Promise);
-  let offlineSessionIds = [];
-  let drmInfo = null;
-
-  let ret = jasmine.createSpyObj('FakeDrmEngine', [
-    'attach', 'configure', 'destroy', 'getDrmInfo', 'getExpiration',
-    'getKeyStatuses', 'getSessionIds', 'getSupportedTypes', 'init',
-    'initialized', 'isSupportedByKeySystem', 'keySystem',
-  ]);
-  ret.attach.and.callFake(resolve);
-  ret.destroy.and.callFake(resolve);
-  ret.init.and.callFake(resolve);
-  ret.initialized.and.returnValue(true);
-  ret.keySystem.and.returnValue('com.example.fake');
-  ret.getExpiration.and.returnValue(Infinity);
-  ret.getKeyStatuses.and.returnValue({});
-  // See shaka.test.ManifestGenerator.protototype.createStream.
-  ret.getSupportedTypes.and.returnValue(
-      ['video/mp4; codecs="avc1.4d401f"']);
-
-  ret.setSessionIds = function(sessions) {
-    offlineSessionIds = sessions;
-  };
-  ret.setDrmInfo = function(info) { drmInfo = info; };
-  ret.getDrmInfo.and.callFake(function() { return drmInfo; });
-  ret.getSessionIds.and.callFake(function() {
-    return offlineSessionIds;
-  });
-  ret.isSupportedByKeySystem.and.returnValue(true);
-
-  return ret;
-};
-
-
-/** @type {jasmine.Spy} */
-shaka.test.FakeDrmEngine.prototype.init;
-
-
-/** @type {jasmine.Spy} */
-shaka.test.FakeDrmEngine.prototype.attach;
-
-
-/** @type {jasmine.Spy} */
-shaka.test.FakeDrmEngine.prototype.getExpiration;
-
-
-/** @param {?shaka.extern.DrmInfo} info */
-shaka.test.FakeDrmEngine.prototype.setDrmInfo;
-
-
-/** @param {!Array.<string>} sessions */
-shaka.test.FakeDrmEngine.prototype.setSessionIds;
-
-
 /**
  * A fake StreamingEngine.
  *