fix: align password policy to 8-72 printable ASCII on register (WealthLedger/backend#60) (#109)

test/app.e2e-spec.ts

@@ -2,7 +2,9 @@ import { INestApplication } from '@nestjs/common';
 import { ConfigService } from '@nestjs/config';
 import { JwtService } from '@nestjs/jwt';
 import { Test, TestingModule } from '@nestjs/testing';
+import * as bcrypt from 'bcrypt';
 import { PARAMS_PROVIDER_TOKEN } from 'nestjs-pino';
+import { randomUUID } from 'node:crypto';
 import request from 'supertest';
 import { App } from 'supertest/types';
 
@@ -265,6 +267,45 @@ describe('Authentication (e2e)', () => {
     expect(await app.get(PrismaService).user.count()).toBe(0);
   });
 
+  it('applies the ASCII 8..72 password policy on register and keeps login lenient', async () => {
+    const validation = (detail: string) => ({
+      status: 400,
+      code: 'VALIDATION_ERROR',
+      errors: [{ pointer: '#/password', detail }],
+    });
+    for (const [index, password] of ['a'.repeat(8), ' '.repeat(2) + 'b'.repeat(70)].entries()) {
+      const credentials = { email: `user${index}@example.com`, password };
+      await request(app.getHttpServer()).post('/api/v1/auth/register').send(credentials).expect(200);
+      await request(app.getHttpServer()).post('/api/v1/auth/login').send(credentials).expect(200);
+    }
+    for (const password of ['a'.repeat(7), 'a'.repeat(73), 'пароль-пароль', 'passw😀rd', 'pass\tword1']) {
+      await request(app.getHttpServer())
+        .post('/api/v1/auth/register')
+        .send({ email: 'rejected@example.com', password })
+        .expect(400)
+        .expect('Content-Type', /application\/problem\+json/)
+        .expect(({ body }: { body: unknown }) =>
+          expect(body).toEqual(validation('must be 8-72 printable ASCII characters')),
+        );
+    }
+    expect(await app.get(PrismaService).user.count()).toBe(2);
+
+    // An account created under the previous policy (Cyrillic, 12+ chars) must still log in.
+    const legacy = { email: 'legacy@example.com', password: 'пароль-пароль' };
+    const prisma = app.get(PrismaService);
+    await prisma.user.create({
+      data: { id: randomUUID(), email: legacy.email, passwordHash: await bcrypt.hash(legacy.password, 4) },
+    });
+    await request(app.getHttpServer()).post('/api/v1/auth/login').send(legacy).expect(200);
+    await request(app.getHttpServer())
+      .post('/api/v1/auth/login')
+      .send({ email: legacy.email, password: 'a'.repeat(73) })
+      .expect(400)
+      .expect(({ body }: { body: unknown }) =>
+        expect(body).toEqual(validation('must not exceed 72 UTF-8 bytes')),
+      );
+  });
+
   it('guards T-Bank connection and never returns a token', async () => {
     const registration = await request(app.getHttpServer())
       .post('/api/v1/auth/register')