fix(mail): remove dead return before sendMail, add firstName personalization

- Remove I18n dependency injection from MailService constructor
- Hardcode German email subject/body strings directly in the service
- Add optional firstName field to userSignUp and forgotPassword methods
- Wire firstName from user object through auth.service.ts call sites
- Add comprehensive unit tests for MailService

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

myteamwallet_backend/src/mail/mail.service.spec.ts

@@ -0,0 +1,61 @@
+import { ConfigService } from '@nestjs/config';
+import { MailerService } from '@nestjs-modules/mailer';
+import { MailService } from './mail.service';
+
+describe('MailService', () => {
+  let service: MailService;
+  let sendMail: jest.Mock;
+  let configGet: jest.Mock;
+
+  beforeEach(() => {
+    sendMail = jest.fn().mockResolvedValue(undefined);
+    configGet = jest.fn().mockReturnValue('https://app.example.com');
+
+    service = new MailService(
+      { sendMail } as unknown as MailerService,
+      { get: configGet } as unknown as ConfigService,
+    );
+  });
+
+  it('sends the activation mail with the confirm-email link', async () => {
+    await service.userSignUp({
+      to: 'user@example.com',
+      data: { hash: 'abc123', firstName: 'Max' },
+    });
+
+    expect(sendMail).toHaveBeenCalledTimes(1);
+    const call = sendMail.mock.calls[0][0];
+    expect(call.to).toBe('user@example.com');
+    expect(call.template).toBe('activation');
+    expect(call.context.url).toBe(
+      'https://app.example.com/confirm-email/abc123',
+    );
+    expect(call.context.firstName).toBe('Max');
+  });
+
+  it('sends the reset-password mail with the password-change link', async () => {
+    await service.forgotPassword({
+      to: 'user@example.com',
+      data: { hash: 'xyz789', firstName: 'Erika' },
+    });
+
+    expect(sendMail).toHaveBeenCalledTimes(1);
+    const call = sendMail.mock.calls[0][0];
+    expect(call.to).toBe('user@example.com');
+    expect(call.template).toBe('reset-password');
+    expect(call.context.url).toBe(
+      'https://app.example.com/password-change/xyz789',
+    );
+    expect(call.context.firstName).toBe('Erika');
+  });
+
+  it('works without a firstName (optional personalization)', async () => {
+    await service.userSignUp({
+      to: 'user@example.com',
+      data: { hash: 'abc123' },
+    });
+
+    const call = sendMail.mock.calls[0][0];
+    expect(call.context.firstName).toBeUndefined();
+  });
+});

myteamwallet_backend/src/mail/mail.service.ts

@@ -1,61 +1,57 @@
 import { MailerService } from '@nestjs-modules/mailer';
 import { Injectable } from '@nestjs/common';
 import { ConfigService } from '@nestjs/config';
-import { I18n, I18nRequestScopeService } from 'nestjs-i18n';
 import { MailData } from './interfaces/mail-data.interface';
 
 @Injectable()
 export class MailService {
   constructor(
-    @I18n()
-    private i18n: I18nRequestScopeService,
     private mailerService: MailerService,
     private configService: ConfigService,
   ) {}
 
-  async userSignUp(mailData: MailData<{ hash: string }>) {
-    return;
+  async userSignUp(
+    mailData: MailData<{ hash: string; firstName?: string | null }>,
+  ) {
+    const actionTitle = 'E-Mail bestätigen';
+    const url = `${this.configService.get('app.frontendDomain')}/confirm-email/${
+      mailData.data.hash
+    }`;
+
     await this.mailerService.sendMail({
       to: mailData.to,
-      subject: await this.i18n.t('common.confirmEmail'),
-      text: `${this.configService.get('app.frontendDomain')}/confirm-email/${
-        mailData.data.hash
-      } ${await this.i18n.t('common.confirmEmail')}`,
+      subject: 'Bestätige deine E-Mail-Adresse',
+      text: `${url} ${actionTitle}`,
       template: 'activation',
       context: {
-        title: await this.i18n.t('common.confirmEmail'),
-        url: `${this.configService.get('app.frontendDomain')}/confirm-email/${
-          mailData.data.hash
-        }`,
-        actionTitle: await this.i18n.t('common.confirmEmail'),
-        app_name: this.configService.get('app.name'),
-        text1: await this.i18n.t('confirm-email.text1'),
-        text2: await this.i18n.t('confirm-email.text2'),
-        text3: await this.i18n.t('confirm-email.text3'),
+        title: 'Bestätige deine E-Mail-Adresse',
+        year: new Date().getFullYear(),
+        firstName: mailData.data.firstName,
+        url,
+        actionTitle,
       },
     });
   }
 
-  async forgotPassword(mailData: MailData<{ hash: string }>) {
-    return;
+  async forgotPassword(
+    mailData: MailData<{ hash: string; firstName?: string | null }>,
+  ) {
+    const actionTitle = 'Passwort zurücksetzen';
+    const url = `${this.configService.get('app.frontendDomain')}/password-change/${
+      mailData.data.hash
+    }`;
+
     await this.mailerService.sendMail({
       to: mailData.to,
-      subject: await this.i18n.t('common.resetPassword'),
-      text: `${this.configService.get('app.frontendDomain')}/password-change/${
-        mailData.data.hash
-      } ${await this.i18n.t('common.resetPassword')}`,
+      subject: actionTitle,
+      text: `${url} ${actionTitle}`,
       template: 'reset-password',
       context: {
-        title: await this.i18n.t('common.resetPassword'),
-        url: `${this.configService.get('app.frontendDomain')}/password-change/${
-          mailData.data.hash
-        }`,
-        actionTitle: await this.i18n.t('common.resetPassword'),
-        app_name: this.configService.get('app.name'),
-        text1: await this.i18n.t('reset-password.text1'),
-        text2: await this.i18n.t('reset-password.text2'),
-        text3: await this.i18n.t('reset-password.text3'),
-        text4: await this.i18n.t('reset-password.text4'),
+        title: actionTitle,
+        year: new Date().getFullYear(),
+        firstName: mailData.data.firstName,
+        url,
+        actionTitle,
       },
     });
   }