diff --git a/karma.conf.cjs b/karma.conf.cjs
index 54380ebd..7d6dbe1a 100644
--- a/karma.conf.cjs
+++ b/karma.conf.cjs
@@ -37,6 +37,7 @@ module.exports = (config) => {
       { pattern: 'node_modules/sinon-chai/**', included: false },
       // modules to test
       { pattern: 'app/localization.js', included: false, type: 'module' },
+      { pattern: 'app/wakelock.js', included: false, type: 'module' },
       { pattern: 'app/webutil.js', included: false, type: 'module' },
       { pattern: 'core/**/*.js', included: false, type: 'module' },
       { pattern: 'vendor/pako/**/*.js', included: false, type: 'module' },
diff --git a/tests/test.wakelock.js b/tests/test.wakelock.js
new file mode 100644
index 00000000..b6544e73
--- /dev/null
+++ b/tests/test.wakelock.js
@@ -0,0 +1,197 @@
+/* jshint expr: true */
+
+import WakeLockManager from '../app/wakelock.js';
+
+class FakeWakeLockSentinal extends EventTarget {
+    constructor() {
+        super();
+        this.released = false;
+    }
+
+    async release() {
+        if (this.released) {
+            return;
+        }
+        this.released = true;
+        this.dispatchEvent(new Event("release"));
+    }
+}
+
+function waitForStateTransition(wakelockManager, newState) {
+    const {promise, resolve} = Promise.withResolvers();
+
+    const eventListener = (event) => {
+        if (event.newState !== newState) {
+            return;
+        }
+        wakelockManager.removeEventListener("testOnlyStateChange", eventListener);
+        resolve();
+    };
+    wakelockManager.addEventListener("testOnlyStateChange", eventListener);
+
+    return promise;
+}
+
+describe('WakeLockManager', function () {
+    "use strict";
+
+    let wakelockRequest;
+    beforeEach(function () {
+        wakelockRequest = sinon.stub(navigator.wakeLock, 'request');
+    });
+    afterEach(function () {
+        wakelockRequest.restore();
+    });
+
+    it('can acquire and release lock', async function () {
+        let wakeLockSentinal = new FakeWakeLockSentinal();
+        wakelockRequest.onFirstCall().resolves(wakeLockSentinal);
+
+        let wlm = new WakeLockManager();
+        expect(wakelockRequest).to.not.have.been.called;
+
+        let done = waitForStateTransition(wlm, 'acquired');
+        wlm.acquire();
+        await done;
+        expect(wakelockRequest).to.have.been.calledOnce;
+        expect(wakeLockSentinal.released).to.be.false;
+
+        done = waitForStateTransition(wlm, 'released');
+        wlm.release();
+        await done;
+        expect(wakelockRequest).to.have.been.calledOnce;
+        expect(wakeLockSentinal.released).to.be.true;
+    });
+
+    it('can release without holding wakelock', async function () {
+        let wlm = new WakeLockManager();
+        wlm.release();
+        expect(wakelockRequest).to.not.have.been.called;
+    });
+
+    it('can release while waiting for wakelock', async function () {
+        let wakeLockSentinal = new FakeWakeLockSentinal();
+        let {promise, resolve} = Promise.withResolvers();
+
+        wakelockRequest.onFirstCall().returns(promise);
+
+        let wlm = new WakeLockManager();
+        expect(wakelockRequest).to.not.have.been.called;
+
+        let seenAcquiring = waitForStateTransition(wlm, 'acquiring');
+        let seenReleasing = waitForStateTransition(wlm, 'releasing');
+        let seenReleased = waitForStateTransition(wlm, 'released');
+
+        wlm.acquire();
+        await seenAcquiring;
+        expect(wakelockRequest).to.have.been.calledOnce;
+
+        // We can call acquire multiple times, while waiting for the promise
+        // to resolve.
+        wlm.acquire();
+        // It should not request a second wakelock.
+        expect(wakelockRequest).to.have.been.calledOnce;
+
+        wlm.release();
+        await seenReleasing;
+
+        expect(wakeLockSentinal.released).to.be.false;
+
+        // Now return the wake lock, we should immediately release it.
+        resolve(wakeLockSentinal);
+        await seenReleased;
+        expect(wakeLockSentinal.released).to.be.true;
+    });
+
+    it('handles visibility loss', async function () {
+        let documentHidden = sinon.stub(document, 'hidden');
+        let documentVisibility = sinon.stub(document, 'visibilityState');
+        afterEach(function () {
+            documentHidden.restore();
+            documentVisibility.restore();
+        });
+        documentHidden.value(false);
+        documentVisibility.value('visible');
+
+        let wakeLockSentinal1 = new FakeWakeLockSentinal();
+        let wakeLockSentinal2 = new FakeWakeLockSentinal();
+        wakelockRequest.onFirstCall().resolves(wakeLockSentinal1);
+        wakelockRequest.onSecondCall().resolves(wakeLockSentinal2);
+
+        let wlm = new WakeLockManager();
+        let seenAcquired = waitForStateTransition(wlm, 'acquired');
+        let seenAwaitingVisible = waitForStateTransition(wlm, 'awaiting_visible');
+
+        wlm.acquire();
+        await seenAcquired;
+        expect(wakelockRequest).to.have.been.calledOnce;
+
+        // Fake a visibility change.
+        documentHidden.value(true);
+        documentVisibility.value('hidden');
+        wakeLockSentinal1.release();
+
+        await seenAwaitingVisible;
+        seenAcquired = waitForStateTransition(wlm, 'acquired');
+
+        // Fake a visibility change back
+        documentHidden.value(false);
+        documentVisibility.value('visible');
+        document.dispatchEvent(new Event('visibilitychange'));
+        await seenAcquired;
+
+        expect(wakelockRequest).to.have.been.calledTwice;
+        expect(wakeLockSentinal2.released).to.be.false;
+    });
+
+    it('can start hidden', async function () {
+        let documentHidden = sinon.stub(document, 'hidden');
+        let documentVisibility = sinon.stub(document, 'visibilityState');
+        afterEach(function () {
+            documentHidden.restore();
+            documentVisibility.restore();
+        });
+        documentHidden.value(true);
+        documentVisibility.value('hidden');
+
+        let wakeLockSentinal = new FakeWakeLockSentinal();
+        wakelockRequest.onFirstCall().resolves(wakeLockSentinal);
+
+        let wlm = new WakeLockManager();
+        let seenAwaitingVisible = waitForStateTransition(wlm, 'awaiting_visible');
+        let seenAcquired = waitForStateTransition(wlm, 'acquired');
+
+        wlm.acquire();
+        await seenAwaitingVisible;
+        expect(wakelockRequest).to.not.have.been.called;
+
+        // Fake a visibility change.
+        documentHidden.value(false);
+        documentVisibility.value('visible');
+        document.dispatchEvent(new Event('visibilitychange'));
+        await seenAcquired;
+
+        expect(wakelockRequest).to.have.been.calledOnce;
+        expect(wakeLockSentinal.released).to.be.false;
+    });
+
+    it('handles acquire errors', async function () {
+        wakelockRequest.onFirstCall().rejects('WakeLockError');
+        let wakeLockSentinal = new FakeWakeLockSentinal();
+        wakelockRequest.onSecondCall().resolves(wakeLockSentinal);
+
+        let wlm = new WakeLockManager();
+
+        let seenError = waitForStateTransition(wlm, 'error');
+        wlm.acquire();
+        await seenError;
+        expect(wakelockRequest).to.have.been.calledOnce;
+
+        // Even though we saw an error previously, it will retry when
+        // requested.
+        let seenAcquired = waitForStateTransition(wlm, 'acquired');
+        wlm.acquire();
+        await seenAcquired;
+        expect(wakelockRequest).to.have.been.calledTwice;
+    });
+});