25 files changed, 265 insertions, 107 deletions
diff --git a/test/data/html/test-document2-script.js b/test/data/html/test-document2-script.js
index 03ec9555..8a183019 100644
--- a/test/data/html/test-document2-script.js
+++ b/test/data/html/test-document2-script.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2021-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/data/html/test-document2.html b/test/data/html/test-document2.html
index fb3adb59..399c3bd8 100644
--- a/test/data/html/test-document2.html
+++ b/test/data/html/test-document2.html
@@ -1,34 +1,40 @@
 <!DOCTYPE html>
 <html>
-    <head>
-        <meta charset="UTF-8">
-        <meta name="viewport" content="width=device-width,initial-scale=1">
-        <title>Yomichan Manual Tests</title>
-        <link rel="icon" type="image/gif" href="data:image/gif;base64,R0lGODlhEAAQAKEBAAAAAP///////////yH5BAEKAAIALAAAAAAQABAAAAImFI6Zpt0B4YkS0TCpq07xbmEgcGVRUpLaI46ZG7ppalY0jDCwUAAAOw==">
-        <link rel="stylesheet" href="test-stylesheet.css">
-        <script src="test-document2-script.js"></script>
-    </head>
-    <style id="container-styles">
-.container {
-    width: 100%;
-    height: 200px;
-    border: 1px solid #d8d8d8;
-    position: relative;
-    box-sizing: border-box;
-}
-.container-inner {
-    background-color: #f8f8f8;
-    padding: 0.5em;
-    position: absolute;
-    left: 0;
-    top: 0;
-    bottom: 0;
-    right: 0;
-}
-.danger {
-    color: #c83c28;
-}
-    </style>
+
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width,initial-scale=1">
+    <title>Yomichan Manual Tests</title>
+    <link rel="icon" type="image/gif"
+        href="data:image/gif;base64,R0lGODlhEAAQAKEBAAAAAP///////////yH5BAEKAAIALAAAAAAQABAAAAImFI6Zpt0B4YkS0TCpq07xbmEgcGVRUpLaI46ZG7ppalY0jDCwUAAAOw==">
+    <link rel="stylesheet" href="test-stylesheet.css">
+    <script src="test-document2-script.js"></script>
+</head>
+<style id="container-styles">
+    .container {
+        width: 100%;
+        height: 200px;
+        border: 1px solid #d8d8d8;
+        position: relative;
+        box-sizing: border-box;
+    }
+
+    .container-inner {
+        background-color: #f8f8f8;
+        padding: 0.5em;
+        position: absolute;
+        left: 0;
+        top: 0;
+        bottom: 0;
+        right: 0;
+    }
+
+    .danger {
+        color: #c83c28;
+    }
+
+</style>
+
 <body>
 
     <h1>Yomichan Manual Tests</h1>
@@ -36,56 +42,62 @@
 
     <y-test>
         <y-description>Standard content.</y-description>
-        <div class="fullscreen-element container"><div class="container-inner">
-            <div>
-                ありがとう
-            </div>
-            <div>
-                <a href="#" class="fullscreen-link">Toggle fullscreen</a>
+        <div class="fullscreen-element container hovertarget">
+            <div class="container-inner">
+                <div>
+                    ありがとう
+                </div>
+                <div>
+                    <a href="#" class="fullscreen-link">Toggle fullscreen</a>
+                </div>
             </div>
-        </div></div>
+        </div>
     </y-test>
 
     <y-test data-shadow-mode="open">
         <y-description>Content inside of an open shadow DOM.</y-description>
-        <div class="template-content-container"></div>
+        <div class="template-content-container hovertarget"></div>
         <template>
             <link rel="stylesheet" href="test-stylesheet.css">
-            <div class="fullscreen-element container"><div class="container-inner">
-                <div>
-                    ありがとう
-                </div>
-                <div>
-                    <a href="#" class="fullscreen-link">Toggle fullscreen</a>
+            <div class="fullscreen-element container">
+                <div class="container-inner">
+                    <div>
+                        ありがとう
+                    </div>
+                    <div>
+                        <a href="#" class="fullscreen-link">Toggle fullscreen</a>
+                    </div>
                 </div>
-            </div></div>
+            </div>
         </template>
     </y-test>
 
     <y-test data-shadow-mode="closed">
         <y-description>Content inside of a closed shadow DOM.</y-description>
-        <div class="template-content-container"></div>
+        <div class="template-content-container hovertarget"></div>
         <template>
             <link rel="stylesheet" href="test-stylesheet.css">
-            <div class="fullscreen-element container"><div class="container-inner">
-                <div>
-                    ありがとう
+            <div class="fullscreen-element container">
+                <div class="container-inner">
+                    <div>
+                        ありがとう
+                    </div>
+                    <div>
+                        <a href="#" class="fullscreen-link">Toggle fullscreen</a>
+                    </div>
                 </div>
-                <div>
-                    <a href="#" class="fullscreen-link">Toggle fullscreen</a>
-                </div>
-            </div></div>
+            </div>
         </template>
     </y-test>
 
     <y-test>
         <y-description>&lt;iframe&gt; element.</y-description>
-        <iframe src="test-document2-frame1.html" allowfullscreen="true" class="container"></iframe>
+        <iframe src="test-document2-frame1.html" allowfullscreen="true" class="container hovertarget"></iframe>
     </y-test>
 
     <y-test data-shadow-mode="open">
         <y-description>&lt;iframe&gt; element inside of an open shadow DOM.</y-description>
-        <div class="template-content-container"></div>
+        <div class="template-content-container hovertarget"></div>
         <template>
             <iframe src="test-document2-frame1.html" allowfullscreen="true" class="container"></iframe>
         </template>
@@ -93,7 +105,7 @@
 
     <y-test data-shadow-mode="closed">
         <y-description>&lt;iframe&gt; element inside of a closed shadow DOM.</y-description>
-        <div class="template-content-container"></div>
+        <div class="template-content-container hovertarget"></div>
         <template>
             <iframe src="test-document2-frame1.html" allowfullscreen="true" class="container"></iframe>
         </template>
@@ -101,22 +113,26 @@
 
     <y-test>
         <y-description>&lt;iframe&gt; element with data URL.</y-description>
-        <iframe id="iframe-with-data-url" src="data:text/html;base64,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" allowfullscreen="true" class="container"></iframe>
+        <iframe id="iframe-with-data-url"
+            src="data:text/html;base64,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"
+            allowfullscreen="true" class="container hovertarget"></iframe>
     </y-test>
 
     <y-test>
         <y-description>&lt;iframe&gt; element with blob URL.</y-description>
-        <iframe id="iframe-with-blob-url" allowfullscreen="true" class="container"></iframe>
+        <iframe id="iframe-with-blob-url" allowfullscreen="true" class="container hovertarget"></iframe>
     </y-test>
 
     <y-test>
         <y-description>&lt;iframe&gt; element with srcdoc.</y-description>
-        <iframe allowfullscreen="true" class="iframe-with-srcdoc container"></iframe>
+        <iframe allowfullscreen="true" class="iframe-with-srcdoc container hovertarget"></iframe>
     </y-test>
 
     <y-test>
-        <y-description>&lt;iframe&gt; element with srcdoc and <code>sandbox="allow-same-origin allow-scripts"</code>.</y-description>
-        <iframe allowfullscreen="true" class="iframe-with-srcdoc container" sandbox="allow-same-origin allow-scripts"></iframe>
+        <y-description>&lt;iframe&gt; element with srcdoc and
+            <code>sandbox="allow-same-origin allow-scripts"</code>.</y-description>
+        <iframe allowfullscreen="true" class="iframe-with-srcdoc container hovertarget"
+            sandbox="allow-same-origin allow-scripts"></iframe>
     </y-test>
 
     <y-test>
@@ -124,41 +140,39 @@
             &lt;iframe&gt; element with srcdoc and <code>sandbox="allow-scripts"</code>.<br>
             <span class="danger">This element is expected to not work.</span>
         </y-description>
-        <iframe allowfullscreen="true" class="iframe-with-srcdoc container" sandbox="allow-scripts"></iframe>
+        <iframe allowfullscreen="true" class="iframe-with-srcdoc container hovertarget"
+            sandbox="allow-scripts"></iframe>
     </y-test>
 
     <y-test>
         <y-description>SVG &lt;img&gt;.</y-description>
-        <img src="test-document2-frame2.svg" class="container" alt="">
+        <img src="test-document2-frame2.svg" class="container hovertarget" alt="">
     </y-test>
 
     <y-test>
         <y-description>SVG &lt;object&gt;.</y-description>
-        <object data="test-document2-frame2.svg" type="image/svg+xml" class="container"></object>
+        <object data="test-document2-frame2.svg" type="image/svg+xml" class="container hovertarget"></object>
     </y-test>
 
     <y-test>
         <y-description>SVG &lt;embed&gt;.</y-description>
-        <embed type="image/svg+xml" src="test-document2-frame2.svg" class="container">
+        <embed type="image/svg+xml" src="test-document2-frame2.svg" class="container hovertarget">
     </y-test>
 
     <y-test>
         <y-description>SVG &lt;iframe&gt;.</y-description>
-        <iframe src="test-document2-frame2.svg" allowfullscreen="true" class="container"></iframe>
+        <iframe src="test-document2-frame2.svg" allowfullscreen="true" class="container hovertarget"></iframe>
     </y-test>
 
     <y-test>
         <y-description>SVG &lt;svg&gt;.</y-description>
-        <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" class="container" style="background-color: #f8f8f8;" focusable="false">
-            <text
-                x="7"
-                y="12"
-                style="
+        <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" class="container hovertarget"
+            style="background-color: #f8f8f8;" focusable="false">
+            <text x="7" y="12" style="
                 font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
                 font-size: 14px;
                 fill: #000000;
-                dominant-baseline: hanging;"
-            >
+                dominant-baseline: hanging;">
                 ありがとう
             </text>
         </svg>
@@ -166,42 +180,43 @@
 
 
     <script>
-(() => {
-    function stringToTypedArray(string) {
-        const array = new Uint8Array(string.length);
-        for (let i = 0; i < string.length; ++i) {
-            array[i] = string.charCodeAt(i);
-        }
-        return array;
-    }
-
-    function dataUrlToContent(dataUrl) {
-        const [, type, isBase64, data] = /^data:([^;]*);(base64,)?([\w\W]*)$/.exec(dataUrl);
-        const content = (
-            isBase64 ?
-            new TextDecoder().decode(stringToTypedArray(atob(data))) :
-            data
-        );
-        return {content, type};
-    }
-
-    function dataUrlToBlob(dataUrl) {
-        const {content, type} = dataUrlToContent(dataUrl);
-        return new Blob([content], {type});
-    }
-
-    for (const element of document.querySelectorAll('y-test')) {
-        setup(element);
-    }
-
-    const iframeWithDataUrl = document.querySelector('#iframe-with-data-url');
-    const iframeWithBlobUrl = document.querySelector('#iframe-with-blob-url');
-    iframeWithBlobUrl.src = URL.createObjectURL(dataUrlToBlob(iframeWithDataUrl.src));
-    for (const iframeWithSrcdoc of document.querySelectorAll('.iframe-with-srcdoc')) {
-        iframeWithSrcdoc.srcdoc = dataUrlToContent(iframeWithDataUrl.src).content;
-    }
-})();
+        (() => {
+            function stringToTypedArray(string) {
+                const array = new Uint8Array(string.length);
+                for (let i = 0; i < string.length; ++i) {
+                    array[i] = string.charCodeAt(i);
+                }
+                return array;
+            }
+
+            function dataUrlToContent(dataUrl) {
+                const [, type, isBase64, data] = /^data:([^;]*);(base64,)?([\w\W]*)$/.exec(dataUrl);
+                const content = (
+                    isBase64 ?
+                        new TextDecoder().decode(stringToTypedArray(atob(data))) :
+                        data
+                );
+                return { content, type };
+            }
+
+            function dataUrlToBlob(dataUrl) {
+                const { content, type } = dataUrlToContent(dataUrl);
+                return new Blob([content], { type });
+            }
+
+            for (const element of document.querySelectorAll('y-test')) {
+                setup(element);
+            }
+
+            const iframeWithDataUrl = document.querySelector('#iframe-with-data-url');
+            const iframeWithBlobUrl = document.querySelector('#iframe-with-blob-url');
+            iframeWithBlobUrl.src = URL.createObjectURL(dataUrlToBlob(iframeWithDataUrl.src));
+            for (const iframeWithSrcdoc of document.querySelectorAll('.iframe-with-srcdoc')) {
+                iframeWithSrcdoc.srcdoc = dataUrlToContent(iframeWithDataUrl.src).content;
+            }
+        })();
     </script>
 
 </body>
+
 </html>
diff --git a/test/playwright/visual.spec.js b/test/playwright/visual.spec.js
new file mode 100644
index 00000000..acb12e97
--- /dev/null
+++ b/test/playwright/visual.spec.js
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2023  Yomitan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+const path = require('path');
+const {test: base, chromium} = require('@playwright/test');
+const root = path.join(__dirname, '..', '..');
+
+export const test = base.extend({
+    context: async ({ }, use) => {
+        const pathToExtension = path.join(root, 'ext');
+        const context = await chromium.launchPersistentContext('', {
+            // headless: false,
+            args: [
+                '--headless=new',
+                `--disable-extensions-except=${pathToExtension}`,
+                `--load-extension=${pathToExtension}`
+            ]
+        });
+        await use(context);
+        await context.close();
+    },
+    extensionId: async ({context}, use) => {
+        let [background] = context.serviceWorkers();
+        if (!background) {
+            background = await context.waitForEvent('serviceworker');
+        }
+
+        const extensionId = background.url().split('/')[2];
+        await use(extensionId);
+    }
+});
+const expect = test.expect;
+
+test('visual', async ({context, page, extensionId}) => {
+    // wait for the on-install welcome.html tab to load, which becomes the foreground tab
+    const welcome = await context.waitForEvent('page');
+    welcome.close(); // close the welcome tab so our main tab becomes the foreground tab -- otherwise, the screenshot can hang
+
+    // open settings
+    await page.goto(`chrome-extension://${extensionId}/settings.html`);
+
+    await expect(page.locator('id=dictionaries')).toBeVisible();
+
+    // get the locator for the disk usage indicator so we can later mask it out of the screenshot
+    const storage_locator = page.locator('.storage-use-finite >> xpath=..');
+
+    // take a simple screenshot of the settings page
+    await expect.soft(page).toHaveScreenshot('settings-fresh.png', {mask: [storage_locator]});
+
+    // load in jmdict_english.zip
+    await page.locator('input[id="dictionary-import-file-input"]').setInputFiles(path.join(root, 'dictionaries/jmdict_english.zip'));
+    await expect(page.locator('id=dictionaries')).toHaveText('Dictionaries (1 installed, 1 enabled)', {timeout: 5 * 60 * 1000});
+
+    // take a screenshot of the settings page with jmdict loaded
+    await expect.soft(page).toHaveScreenshot('settings-jmdict-loaded.png', {mask: [storage_locator]});
+
+    const screenshot = async (doc_number, test_number, el, offset) => {
+        const test_name = 'doc' + doc_number + '-test' + test_number;
+
+        const box = await el.boundingBox();
+
+        // find the popup frame if it exists
+        let popup_frame = page.frames().find((f) => f.url().includes('popup.html'));
+
+        // otherwise prepare for it to be attached
+        let frame_attached;
+        if (popup_frame === undefined) {
+            frame_attached = page.waitForEvent('frameattached');
+        }
+        await page.mouse.move(box.x + offset.x, box.y + offset.y, {steps: 10}); // hover over the test
+        if (popup_frame === undefined) {
+            popup_frame = await frame_attached; // wait for popup to be attached
+        }
+        try {
+            await (await popup_frame.frameElement()).waitForElementState('visible', {timeout: 500});  // some tests don't have a popup, so don't fail if it's not there; TODO: check if the popup is expected to be there
+        } catch (error) {
+            console.log(test_name + ' has no popup');
+        }
+
+        await page.bringToFront(); // bring the page to the foreground so the screenshot doesn't hang; for some reason the frames result in page being in the background
+        await expect.soft(page).toHaveScreenshot(test_name + '.png');
+
+        await page.mouse.click(0, 0); // click away so popup disappears
+        await (await popup_frame.frameElement()).waitForElementState('hidden'); // wait for popup to disappear
+    };
+
+    // Load test-document1.html
+    await page.goto('file://' + path.join(root, 'test/data/html/test-document1.html'));
+    await page.setViewportSize({width: 1000, height: 1800});
+    await page.keyboard.down('Shift');
+    let i = 1;
+    for (const el of await page.locator('div > *:nth-child(1)').elementHandles()) {
+        await screenshot(1, i, el, {x: 6, y: 6});
+        i++;
+    }
+
+    // Load test-document2.html
+    await page.goto('file://' + path.join(root, 'test/data/html/test-document2.html'));
+    await page.setViewportSize({width: 1000, height: 4500});
+    await page.keyboard.down('Shift');
+    i = 1;
+    for (const el of await page.locator('.hovertarget').elementHandles()) {
+        await screenshot(2, i, el, {x: 15, y: 15});
+        i++;
+    }
+});
diff --git a/test/test-all.js b/test/test-all.js
index f1a6cb27..d187879a 100644
--- a/test/test-all.js
+++ b/test/test-all.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-anki-note-builder.js b/test/test-anki-note-builder.js
index 21aa89bc..ba937302 100644
--- a/test/test-anki-note-builder.js
+++ b/test/test-anki-note-builder.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2021-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-build-libs.js b/test/test-build-libs.js
index 6305de04..496f43f8 100644
--- a/test/test-build-libs.js
+++ b/test/test-build-libs.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-cache-map.js b/test/test-cache-map.js
index 2bb82f83..863c6ace 100644
--- a/test/test-cache-map.js
+++ b/test/test-cache-map.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-core.js b/test/test-core.js
index 8ca523dd..b42f8cf2 100644
--- a/test/test-core.js
+++ b/test/test-core.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-css-json.js b/test/test-css-json.js
index 09f3cb1b..ddeee6bd 100644
--- a/test/test-css-json.js
+++ b/test/test-css-json.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2021-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-database.js b/test/test-database.js
index 6124f42e..c4cd504a 100644
--- a/test/test-database.js
+++ b/test/test-database.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-deinflector.js b/test/test-deinflector.js
index 94bf80d0..ea8af292 100644
--- a/test/test-deinflector.js
+++ b/test/test-deinflector.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-dictionary.js b/test/test-dictionary.js
index 477567b1..d4390e19 100644
--- a/test/test-dictionary.js
+++ b/test/test-dictionary.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-document-util.js b/test/test-document-util.js
index ad4da269..a2458b61 100644
--- a/test/test-document-util.js
+++ b/test/test-document-util.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-dom-text-scanner.js b/test/test-dom-text-scanner.js
index f3bd4599..37017b01 100644
--- a/test/test-dom-text-scanner.js
+++ b/test/test-dom-text-scanner.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-hotkey-util.js b/test/test-hotkey-util.js
index 840678bb..34f1eb26 100644
--- a/test/test-hotkey-util.js
+++ b/test/test-hotkey-util.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-japanese-util.js b/test/test-japanese-util.js
index 6aa426d5..4395a11e 100644
--- a/test/test-japanese-util.js
+++ b/test/test-japanese-util.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-jsdom.js b/test/test-jsdom.js
index a56a579e..5078c240 100644
--- a/test/test-jsdom.js
+++ b/test/test-jsdom.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2021-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-json-schema.js b/test/test-json-schema.js
index aedf1126..35ecc5e9 100644
--- a/test/test-json-schema.js
+++ b/test/test-json-schema.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-manifest.js b/test/test-manifest.js
index 1d98c41b..b52152de 100644
--- a/test/test-manifest.js
+++ b/test/test-manifest.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-object-property-accessor.js b/test/test-object-property-accessor.js
index 1de1fc36..d225e893 100644
--- a/test/test-object-property-accessor.js
+++ b/test/test-object-property-accessor.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-options-util.js b/test/test-options-util.js
index 05af4214..2be6b2f7 100644
--- a/test/test-options-util.js
+++ b/test/test-options-util.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-profile-conditions-util.js b/test/test-profile-conditions-util.js
index bb2e94ad..d5187425 100644
--- a/test/test-profile-conditions-util.js
+++ b/test/test-profile-conditions-util.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-text-source-map.js b/test/test-text-source-map.js
index 1d697ae4..dd8d3bbd 100644
--- a/test/test-text-source-map.js
+++ b/test/test-text-source-map.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-translator.js b/test/test-translator.js
index 49128f35..485eb665 100644
--- a/test/test-translator.js
+++ b/test/test-translator.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
diff --git a/test/test-workers.js b/test/test-workers.js
index 86ce7606..b4ec4d7d 100644
--- a/test/test-workers.js
+++ b/test/test-workers.js
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2023  Yomitan Authors
  * Copyright (C) 2020-2022  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify