tests: add coverage for src/actions/ (15 files) and src/lib/{admin,auth} (3 files)

- src/actions coverage: 2.4% -> 13.55%
- src/lib/admin coverage: 44.3% -> 84.81%
- src/lib/auth coverage: 90.52%
- vitest.config.ts: exclude .next.prev/ from test discovery

src/actions/applications.test.ts

@@ -0,0 +1,100 @@
+import { redirect } from "next/navigation";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { auth } from "@/lib/auth";
+import { prisma } from "@/lib/prisma";
+import { clientIp, rateLimit } from "@/lib/rate-limit";
+import { applyStaff, applyTeam } from "./applications";
+
+vi.mock("@/lib/auth", () => ({ auth: vi.fn() }));
+vi.mock("@/lib/prisma", () => ({
+	prisma: { websiteStaffApplications: { findFirst: vi.fn(), create: vi.fn() } },
+}));
+vi.mock("@/lib/rate-limit", () => ({ clientIp: vi.fn(), rateLimit: vi.fn() }));
+vi.mock("next/cache", () => ({ revalidatePath: vi.fn() }));
+vi.mock("next/navigation", () => ({ redirect: vi.fn() }));
+
+const fakeForm = (data: Record<string, string>) => ({
+	get: (key: string) => data[key] ?? null,
+});
+
+beforeEach(() => {
+	vi.clearAllMocks();
+	vi.mocked(auth).mockResolvedValue({ user: { id: "42" } } as never);
+	vi.mocked(clientIp).mockResolvedValue("127.0.0.1");
+	vi.mocked(rateLimit).mockResolvedValue({ ok: true });
+});
+
+describe("applyStaff", () => {
+	it("submits staff application", async () => {
+		vi.mocked(prisma.websiteStaffApplications.findFirst).mockResolvedValue(
+			null,
+		);
+		vi.mocked(prisma.websiteStaffApplications.create).mockResolvedValue(
+			{} as never,
+		);
+		await applyStaff(
+			fakeForm({
+				rankId: "3",
+				content: "I want to help!",
+			}) as unknown as FormData,
+		);
+		expect(prisma.websiteStaffApplications.create).toHaveBeenCalled();
+		expect(redirect).toHaveBeenCalledWith("/apply/staff?submitted=1");
+	});
+
+	it("redirects to login when not authenticated", async () => {
+		vi.mocked(auth).mockResolvedValue(null);
+		await applyStaff(fakeForm({}) as unknown as FormData);
+		expect(redirect).toHaveBeenCalledWith("/login");
+	});
+
+	it("returns duplicate status when application exists", async () => {
+		vi.mocked(prisma.websiteStaffApplications.findFirst).mockResolvedValue({
+			id: 1,
+		} as never);
+		await applyStaff(
+			fakeForm({
+				rankId: "3",
+				content: "I want to help!",
+			}) as unknown as FormData,
+		);
+		expect(prisma.websiteStaffApplications.create).not.toHaveBeenCalled();
+		expect(redirect).toHaveBeenCalledWith("/apply/staff?error=duplicate");
+	});
+
+	it("handles rate limit", async () => {
+		vi.mocked(rateLimit).mockResolvedValue({ ok: false });
+		await applyStaff(
+			fakeForm({
+				rankId: "3",
+				content: "I want to help!",
+			}) as unknown as FormData,
+		);
+		expect(redirect).toHaveBeenCalledWith("/apply/staff?error=ratelimit");
+	});
+});
+
+describe("applyTeam", () => {
+	it("submits team application", async () => {
+		vi.mocked(prisma.websiteStaffApplications.findFirst).mockResolvedValue(
+			null,
+		);
+		vi.mocked(prisma.websiteStaffApplications.create).mockResolvedValue(
+			{} as never,
+		);
+		await applyTeam(
+			fakeForm({
+				teamId: "2",
+				content: "I want to join team!",
+			}) as unknown as FormData,
+		);
+		expect(prisma.websiteStaffApplications.create).toHaveBeenCalled();
+		expect(redirect).toHaveBeenCalledWith("/apply/team?submitted=1");
+	});
+
+	it("redirects to login when not authenticated", async () => {
+		vi.mocked(auth).mockResolvedValue(null);
+		await applyTeam(fakeForm({}) as unknown as FormData);
+		expect(redirect).toHaveBeenCalledWith("/login");
+	});
+});