test(frontend): add comprehensive tests for components, hooks, and state

Add 84 new tests covering Jotai atoms (play/watch state transitions,
game timing, score management), utility functions (calcCodeSize,
checkGameResultKind), UI components (SubmitStatusLabel, LeftTime,
SubmitButton, InputText, BorderedContainerWithCaption,
FoldableBorderedContainerWithCaption, UserIcon, PlayerNameAndIcon),
and the usePageTitle hook.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/frontend/app/hooks/usePageTitle.test.ts b/frontend/app/hooks/usePageTitle.test.ts
new file mode 100644
index 0000000..2e1a3ec
--- /dev/null
+++ b/frontend/app/hooks/usePageTitle.test.ts
@@ -0,0 +1,23 @@
+/**
+ * @vitest-environment jsdom
+ */
+import { renderHook } from "@testing-library/react";
+import { describe, expect, test } from "vitest";
+import { usePageTitle } from "./usePageTitle";
+
+describe("usePageTitle", () => {
+	test("sets document title", () => {
+		renderHook(() => usePageTitle("Test Page"));
+		expect(document.title).toBe("Test Page");
+	});
+
+	test("updates document title when value changes", () => {
+		const { rerender } = renderHook(({ title }) => usePageTitle(title), {
+			initialProps: { title: "First" },
+		});
+		expect(document.title).toBe("First");
+
+		rerender({ title: "Second" });
+		expect(document.title).toBe("Second");
+	});
+});