diff --git a/tests/jest/plugins/tts/AbstractTTSEngine.test.js b/tests/jest/plugins/tts/AbstractTTSEngine.test.js
index d35464196..2ad26a3bd 100644
--- a/tests/jest/plugins/tts/AbstractTTSEngine.test.js
+++ b/tests/jest/plugins/tts/AbstractTTSEngine.test.js
@@ -5,7 +5,7 @@ import PageChunkIterator from '@/src/plugins/tts/PageChunkIterator.js';
 /** @typedef {import('@/src/plugins/tts/AbstractTTSEngine.js').TTSEngineOptions} TTSEngineOptions */
 
 // Skipping because it's flaky. Fix in #672
-describe.skip('AbstractTTSEngine', () => {
+describe('AbstractTTSEngine', () => {
   test('stops playing once done', async () => {
     class DummyEngine extends AbstractTTSEngine {
       getVoices() { return []; }
@@ -20,6 +20,63 @@ describe.skip('AbstractTTSEngine', () => {
   });
 });
 
+describe('Non Flaky AbstractTTSEngine', () => {
+  let d;
+  beforeEach(() => {
+    class DummyEngine extends AbstractTTSEngine {
+      getVoices() { return []; }
+    }
+    d = new DummyEngine(DUMMY_TTS_ENGINE_OPTS);
+  });
+
+  test('should trigger start event', () => {
+    const triggerStub = sinon.spy(d.events, 'trigger');
+    d._chunkIterator = { next: sinon.stub().resolves(PageChunkIterator.AT_END) };
+    d.start(0, 0);
+    expect(triggerStub.callCount).toBe(1);
+  });
+
+  test('should handle pause and resume events for state changes', () => {
+    const triggerStub = sinon.spy(d.events, 'trigger');
+    d.activeSound = { pause: sinon.stub() };
+
+    d.paused = true;
+    d.pause();
+    expect(triggerStub.callCount).toBe(0);
+
+    d.paused = false;
+    d.pause();
+    expect(triggerStub.callCount).toBe(1);
+    expect(d.paused).toBeTruthy();
+  });
+
+  test('should trigger resume event', () => {
+    const triggerStub = sinon.spy(d.events, 'trigger');
+    d.activeSound = { resume: sinon.stub() };
+
+    d.paused = true;
+    d.resume();
+    expect(triggerStub.callCount).toBe(1);
+    expect(d.paused).toBeFalsy();
+  });
+
+  test('togglePlayPause', () => {
+    const triggerSpy = sinon.spy(d.events, 'trigger');
+    d.activeSound = {
+      resume: sinon.stub(),
+      pause: sinon.stub(),
+    };
+    d.paused = true;
+    d.togglePlayPause();
+    expect(d.paused).toBeFalsy();
+
+    d.togglePlayPause();
+    expect(d.paused).toBeTruthy();
+    expect(triggerSpy.callCount).toBe(2);
+  });
+
+});
+
 for (const dummyVoice of [dummyVoiceHyphens, dummyVoiceUnderscores]) {
   describe(`getBestBookVoice with BCP47 ${dummyVoice == dummyVoiceUnderscores ? '+' : '-'} underscores`, () => {
     const { getBestBookVoice } = AbstractTTSEngine;
diff --git a/tests/jest/plugins/tts/WebTTSEngine.test.js b/tests/jest/plugins/tts/WebTTSEngine.test.js
index 6eeb0fb59..e35a496e4 100644
--- a/tests/jest/plugins/tts/WebTTSEngine.test.js
+++ b/tests/jest/plugins/tts/WebTTSEngine.test.js
@@ -15,11 +15,13 @@ beforeEach(() => {
     this.text = text;
     Object.assign(this, eventTargetMixin());
   };
+  // mockSomeConstantValueGetter.mockReturnValue(false);
 });
 
 afterEach(() => {
   delete window.speechSynthesis;
   delete window.SpeechSynthesisUtterance;
+  // mockSomeConstantValueGetter.mockReset();
 });
 
 describe('WebTTSEngine', () => {
@@ -92,6 +94,17 @@ describe('WebTTSSound', () => {
     });
   });
 
+  test('reloading should store the charIndex for the sound', async () => {
+    const sound = new WebTTSSound('hello world');
+    sound.load();
+    sound.play();
+    sound.utterance.dispatchEvent('pause', {target: {text: 'hello world'}});
+    await afterEventLoop();
+    sound.reload();
+    await afterEventLoop();
+    expect(sound._charIndex).not.toBe(0);
+  });
+
   describe('_chromePausingBugFix', () => {
     /** @type {sinon.SinonFakeTimers} */
     let clock = null;
@@ -167,12 +180,69 @@ describe('WebTTSSound', () => {
     sound.started = true;
     sound.paused = true;
     const dispatchSpy = sinon.spy(sound.utterance, 'dispatchEvent');
+    sound.play = sinon.stub();
     sound.resume();
     clock.tick(1000);
+    sound.stop = sinon.stub();
     clock.restore();
 
     await afterEventLoop();
     expect(dispatchSpy.callCount).toBe(1);
+    expect(sound.play.callCount).toBe(1);
     expect(dispatchSpy.args[0][0].type).toBe('resume');
   });
+
+  test('resume continues playing if not started or stopped', async() => {
+    const sound = new WebTTSSound('hello world');
+    sound.load();
+    sound.play = sinon.stub();
+    sound.resume();
+    await afterEventLoop();
+    expect(sound.play.callCount).toBe(1);
+  });
+
+  test('fire finish event', async () => {
+    const sound = new WebTTSSound('hello world');
+    sound.load();
+    const dispatchSpy = sinon.spy(sound.utterance, 'dispatchEvent');
+    sound.play();
+    sound.stop = sinon.stub();
+    sound.finish();
+    await afterEventLoop();
+    expect(dispatchSpy.args[0][0].type).toBe('finish');
+  });
+
+  test('pause immediately fails if already in paused state', async() => {
+    const sound = new WebTTSSound('pausing on a pause');
+    sound.load();
+    sound.play();
+    const checkSpeech = jest.spyOn(speechSynthesis, 'pause');
+    sound.paused = true;
+    sound.pause();
+    expect(checkSpeech).toHaveBeenCalledTimes(0);
+  });
+});
+
+const mockSomeConstantValueGetter = jest.fn();
+jest.mock('../../../../src/plugins/tts/utils', () => ({
+  ...jest.requireActual('../../../../src/plugins/tts/utils'),
+  get DEBUG_READ_ALOUD() {
+    return mockSomeConstantValueGetter;
+  },
+}));
+
+describe('DEBUG_READ_ALOUD', () => {
+  test('debug listeners should be added', async () => {
+    mockSomeConstantValueGetter.mockReturnValue(true);
+    const sound = new WebTTSSound('debug world');
+    console.log = sinon.stub();
+    expect(console.log.callCount).toBe(0);
+    sound.load();
+    const EVENTS = ['pause', 'resume', 'start', 'end', 'error', 'boundary', 'mark', 'finish'];
+
+    EVENTS.forEach((event) => {
+      sound.utterance.dispatchEvent(event);
+    });
+    expect(console.log.callCount).toBe(EVENTS.length);
+  });
 });
diff --git a/tests/jest/plugins/tts/utils.test.js b/tests/jest/plugins/tts/utils.test.js
index 6892bd44c..be32894a4 100644
--- a/tests/jest/plugins/tts/utils.test.js
+++ b/tests/jest/plugins/tts/utils.test.js
@@ -40,6 +40,7 @@ describe('toISO6391', () => {
     expect(toISO6391('fr')).toBe('fr');
     expect(toISO6391('SQ')).toBe('sq');
     expect(toISO6391('aa')).toBe('aa');
+    expect(toISO6391('zh-hans')).toBe('zh-hans');
   });
 
   test('ISO 639-2/T', () => {