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, 41 insertions, 0 deletions

diff --git a/frontend/app/components/SubmitButton.test.tsx b/frontend/app/components/SubmitButton.test.tsx
new file mode 100644
index 0000000..ebf3416
--- /dev/null
+++ b/frontend/app/components/SubmitButton.test.tsx
@@ -0,0 +1,41 @@
+/**
+ * @vitest-environment jsdom
+ */
+import { cleanup, render, screen } from "@testing-library/react";
+import { afterEach, describe, expect, test } from "vitest";
+import SubmitButton from "./SubmitButton";
+
+afterEach(() => {
+	cleanup();
+});
+
+describe("SubmitButton", () => {
+	test("renders children text", () => {
+		render(<SubmitButton>Submit</SubmitButton>);
+		expect(screen.getByText("Submit")).toBeDefined();
+	});
+
+	test("renders as a button element", () => {
+		render(<SubmitButton>Click</SubmitButton>);
+		const button = screen.getByText("Click");
+		expect(button.tagName).toBe("BUTTON");
+	});
+
+	test("can be disabled", () => {
+		render(<SubmitButton disabled>Submit</SubmitButton>);
+		const button = screen.getByText("Submit") as HTMLButtonElement;
+		expect(button.disabled).toBe(true);
+	});
+
+	test("is not disabled by default", () => {
+		render(<SubmitButton>Submit</SubmitButton>);
+		const button = screen.getByText("Submit") as HTMLButtonElement;
+		expect(button.disabled).toBe(false);
+	});
+
+	test("has sky-600 background styling", () => {
+		render(<SubmitButton>Submit</SubmitButton>);
+		const button = screen.getByText("Submit");
+		expect(button.className).toContain("bg-sky-600");
+	});
+});