Localize the renderer UI into Chinese behind the language setting

tests/unit/i18n-coverage.test.ts

@@ -0,0 +1,53 @@
+import { readdirSync, readFileSync } from "node:fs";
+import { join } from "node:path";
+import { describe, expect, test } from "vitest";
+import { zh } from "../../src/renderer/src/i18n/zh";
+
+const RENDERER_ROOT = join(__dirname, "../../src/renderer/src");
+
+function rendererSources(dir: string): string[] {
+  const out: string[] = [];
+  for (const entry of readdirSync(dir, { withFileTypes: true })) {
+    const path = join(dir, entry.name);
+    if (entry.isDirectory()) out.push(...rendererSources(path));
+    else if (/\.(ts|tsx)$/.test(entry.name)) out.push(path);
+  }
+  return out;
+}
+
+describe("i18n coverage", () => {
+  const sources = rendererSources(RENDERER_ROOT);
+
+  test("every t() key has a Chinese translation", () => {
+    const missing = new Set<string>();
+    for (const path of sources) {
+      const src = readFileSync(path, "utf8");
+      for (const match of src.matchAll(/\bt\(\s*"((?:[^"\\]|\\.)*)"/g)) {
+        if (!(match[1] in zh)) missing.add(match[1]);
+      }
+    }
+    expect([...missing].sort()).toEqual([]);
+  });
+
+  test("t() keys are plain double-quoted literals", () => {
+    const offenders: string[] = [];
+    for (const path of sources) {
+      if (path.includes("/i18n/") || path.includes("\\i18n\\")) continue;
+      const src = readFileSync(path, "utf8");
+      // The key must be the literal first argument — expressions (ternaries,
+      // variables, other quotes) hide keys from extraction and translation.
+      if (/\bt\(\s*(?!")/.test(src)) offenders.push(path.slice(RENDERER_ROOT.length + 1));
+    }
+    expect(offenders).toEqual([]);
+  });
+
+  test("translations keep their placeholders", () => {
+    const broken: string[] = [];
+    for (const [key, value] of Object.entries(zh)) {
+      const wanted = [...key.matchAll(/\{(\w+)\}/g)].map((match) => match[1]).sort();
+      const got = [...value.matchAll(/\{(\w+)\}/g)].map((match) => match[1]).sort();
+      if (wanted.join(",") !== got.join(",")) broken.push(key);
+    }
+    expect(broken).toEqual([]);
+  });
+});