added api logic, vitest, minimal testing ui

api/tests/helpers.ts

@@ -0,0 +1,42 @@
+// tests/helpers.ts
+import { PrismaClient } from "@prisma/client";
+
+export const prisma = new PrismaClient();
+
+// Handy test user id
+export const U = "demo-user-1";
+
+// Monotonic id helpers so we never collide with existing rows
+let cseq = 0;
+let pseq = 0;
+export const cid = (base = "c") => `${base}_${Date.now()}_${cseq++}`;
+export const pid = (base = "p") => `${base}_${Date.now()}_${pseq++}`;
+
+/**
+ * Hard-reset all data for a given user in dependency-safe order.
+ * Also deletes the user row so tests can re-create/upsert cleanly.
+ */
+export async function resetUser(userId: string) {
+  await prisma.$transaction([
+    prisma.allocation.deleteMany({ where: { userId } }),
+    prisma.transaction.deleteMany({ where: { userId } }),
+    prisma.incomeEvent.deleteMany({ where: { userId } }),
+    prisma.fixedPlan.deleteMany({ where: { userId } }),
+    prisma.variableCategory.deleteMany({ where: { userId } }),
+  ]);
+  await prisma.user.deleteMany({ where: { id: userId } });
+}
+
+/** Ensure the user exists (id stable) */
+export async function ensureUser(userId: string) {
+  await prisma.user.upsert({
+    where: { id: userId },
+    update: {},
+    create: { id: userId, email: `${userId}@demo.local` },
+  });
+}
+
+/** Close Prisma after all tests */
+export async function closePrisma() {
+  await prisma.$disconnect();
+}