test: define housekeeping migration inventory

src/features/housekeeping/migration/discover-legacy-pages.test.ts

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+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
+import { discoverLegacyPages } from "./discover-legacy-pages";
+
+const temporaryRoots: string[] = [];
+
+afterEach(() => {
+	for (const root of temporaryRoots.splice(0)) {
+		rmSync(root, { force: true, recursive: true });
+	}
+});
+
+function createRouteTree(files: readonly string[]): string {
+	const root = mkdtempSync(join(tmpdir(), "housekeeping-routes-"));
+	temporaryRoots.push(root);
+
+	for (const file of files) {
+		const path = join(root, file);
+		mkdirSync(join(path, ".."), { recursive: true });
+		writeFileSync(path, "export default function Page() {}\n");
+	}
+
+	return root;
+}
+
+describe("discoverLegacyPages", () => {
+	it("discovers the exact legacy administration inventory", () => {
+		const pages = discoverLegacyPages();
+
+		expect(pages).toHaveLength(137);
+		expect(pages).toContainEqual({
+			surface: "admin",
+			legacyPath: "/admin/users/:id/edit",
+			sourceFile: "src/app/admin/users/[id]/edit/page.tsx",
+		});
+		expect(pages).toContainEqual({
+			surface: "mod",
+			legacyPath: "/mod/cfh/:id",
+			sourceFile: "src/app/mod/cfh/[id]/page.tsx",
+		});
+	});
+
+	it("sorts a controlled route tree by surface, route, then source file", () => {
+		const root = createRouteTree([
+			"src/app/mod/zebra/page.tsx",
+			"src/app/admin/users/[id]/page.tsx",
+			"src/app/admin/(hidden)/alpha/page.tsx",
+			"src/app/admin/users/[...slug]/page.tsx",
+			"src/app/mod/(group)/aardvark/page.tsx",
+		]);
+
+		expect(discoverLegacyPages(root)).toEqual([
+			{
+				surface: "admin",
+				legacyPath: "/admin/alpha",
+				sourceFile: "src/app/admin/(hidden)/alpha/page.tsx",
+			},
+			{
+				surface: "admin",
+				legacyPath: "/admin/users/:id",
+				sourceFile: "src/app/admin/users/[id]/page.tsx",
+			},
+			{
+				surface: "admin",
+				legacyPath: "/admin/users/:slug*",
+				sourceFile: "src/app/admin/users/[...slug]/page.tsx",
+			},
+			{
+				surface: "mod",
+				legacyPath: "/mod/aardvark",
+				sourceFile: "src/app/mod/(group)/aardvark/page.tsx",
+			},
+			{
+				surface: "mod",
+				legacyPath: "/mod/zebra",
+				sourceFile: "src/app/mod/zebra/page.tsx",
+			},
+		]);
+	});
+});