fix: finish 2.9.0 plugin moves and get every check green

src/backend/tests/database/routes/plugin-legacy-paths.test.ts

@@ -0,0 +1,60 @@
+/**
+ * contributes.http.legacyPaths: an old URL under "/<plugin id>/" reaches the
+ * plugin's router with that prefix removed, and nothing else is caught.
+ */
+
+import express from "express";
+import request from "supertest";
+import { describe, expect, it, vi } from "vitest";
+
+const routers = vi.hoisted(() => new Map<string, express.Router>());
+
+vi.mock("../../../plugins/http.js", () => ({
+  getPluginRouter: (id: string) => routers.get(id),
+}));
+
+const { mountPluginLegacyPaths } =
+  await import("../../../database/routes/plugin-api-routes.js");
+
+function appWith(active: Array<{ id: string; legacyPaths: string[] }>) {
+  const app = express();
+  app.get("/core/route", (_req, res) => res.json({ from: "core" }));
+  mountPluginLegacyPaths(app, () => active);
+  app.use((_req, res) => res.status(404).json({ from: "fallthrough" }));
+  return app;
+}
+
+describe("mountPluginLegacyPaths", () => {
+  const router = express.Router();
+  router.post("/webhook/:token", (req, res) =>
+    res.json({ token: req.params.token }),
+  );
+  routers.set("automations", router);
+
+  it("serves an old URL through the plugin's router", async () => {
+    const app = appWith([
+      { id: "automations", legacyPaths: ["/automations/webhook"] },
+    ]);
+    const response = await request(app).post("/automations/webhook/abc123");
+    expect(response.status).toBe(200);
+    expect(response.body).toEqual({ token: "abc123" });
+  });
+
+  it("leaves paths outside the declared prefixes alone", async () => {
+    const app = appWith([
+      { id: "automations", legacyPaths: ["/automations/webhook"] },
+    ]);
+    expect((await request(app).get("/automations/other")).body).toEqual({
+      from: "fallthrough",
+    });
+    expect((await request(app).get("/core/route")).body).toEqual({
+      from: "core",
+    });
+  });
+
+  it("answers 404 while the plugin serves no router", async () => {
+    const app = appWith([{ id: "gone", legacyPaths: ["/gone/hook"] }]);
+    const response = await request(app).post("/gone/hook/x");
+    expect(response.status).toBe(404);
+  });
+});