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

src/common/dto-validation.spec.ts

@@ -1,6 +1,6 @@
 import { BadRequestException, ValidationPipe } from '@nestjs/common';
 
-import { CredentialsDto } from '../modules/auth/presentation/auth.dto';
+import { LoginDto, RegisterDto } from '../modules/auth/presentation/auth.dto';
 import {
   CreateBankCardDto,
   UpdateBankCardDto,
@@ -11,7 +11,7 @@ describe('DTO validation', () => {
     forbidUnknownValues: true, transform: true, whitelist: true });
 
   it('requires credentials and normalizes a valid email', async () => {
-    const metadata = { type: 'body' as const, metatype: CredentialsDto };
+    const metadata = { type: 'body' as const, metatype: RegisterDto };
     await expect(pipe.transform({}, metadata)).rejects.toBeInstanceOf(
       BadRequestException,
     );
@@ -29,6 +29,59 @@ describe('DTO validation', () => {
     });
   });
 
+  // Test intent: register accepts 8..72 printable ASCII characters only (bcrypt
+  // reads 72 bytes, so non-ASCII could be silently truncated); login only caps
+  // bytes so accounts created under the older policy can still sign in.
+  describe('password policy', () => {
+    const register = { type: 'body' as const, metatype: RegisterDto };
+    const login = { type: 'body' as const, metatype: LoginDto };
+    const body = (password: string) => ({ email: 'user@example.com', password });
+    const accepts = (value: unknown, metadata: typeof login | typeof register) =>
+      pipe.transform(value, metadata).then(
+        () => true,
+        (error: unknown) => {
+          if (!(error instanceof BadRequestException)) throw error;
+          return false;
+        },
+      );
+
+    it.each([
+      ['7 chars', 'a'.repeat(7), false],
+      ['8 chars', 'a'.repeat(8), true],
+      ['72 chars', 'a'.repeat(72), true],
+      ['73 chars', 'a'.repeat(73), false],
+      ['all printable symbols and space', 'Aa1 !~"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}', true],
+      ['Cyrillic, 8+ chars', 'пароль-пароль', false],
+      ['emoji', 'passw😀rd', false],
+      ['tab', 'pass\tword1', false],
+      ['newline', 'password1\n', false],
+      ['DEL', 'password\x7f1', false],
+      ['non-string', 12345678, false],
+    ])('register: %s', async (_, password, accepted) => {
+      await expect(accepts(body(password as string), register)).resolves.toBe(accepted);
+    });
+
+    it('register keeps raw whitespace untouched', async () => {
+      const password = '  spaced pass  ';
+      await expect(pipe.transform(body(password), register)).resolves.toEqual(
+        body(password),
+      );
+    });
+
+    it.each([
+      ['legacy Cyrillic password', 'пароль-пароль', true],
+      ['short legacy password', 'short', true],
+      ['72 bytes', 'a'.repeat(72), true],
+      ['73 bytes', 'a'.repeat(73), false],
+      ['36 Cyrillic letters = 72 bytes', 'я'.repeat(36), true],
+      ['37 Cyrillic letters = 74 bytes', 'я'.repeat(37), false],
+      ['empty', '', false],
+      ['non-string', 12345678, false],
+    ])('login: %s', async (_, password, accepted) => {
+      await expect(accepts(body(password as string), login)).resolves.toBe(accepted);
+    });
+  });
+
   it('requires and validates nested money in a new card', async () => {
     const metadata = { type: 'body' as const, metatype: CreateBankCardDto };
     const card = {