Implement tests for all basic functionality

Also fix sendMail's options to accept the template and context properties.

jest.config.js

@@ -1,19 +1,17 @@
 require('ts-node/register');
-require('./server/polyfills');
 
 module.exports = {
   'moduleFileExtensions': [
-    'ts',
     'js',
-    'json'
+    'json',
+    'ts',
   ],
-  'transform': {
-    '^.+\\.ts$': 'ts-jest'
-  },
-  'testRegex': '\/lib\/.*\\.spec\\.(ts|js)$',
+  'rootDir': 'lib',
+  'testRegex': '/lib/.*\\.spec\\.(ts|js)$',
   'globals': {
     'ts-jest': {
-      'tsConfigFile': 'tsconfig.json'
+      'tsConfig': 'tsconfig.json'
     }
-  }
+  },
+  'preset': 'ts-jest',
 };

lib/interfaces/mailer-send-mail-options.interface.ts

@@ -0,0 +1,7 @@
+/** Dependencies **/
+import { SendMailOptions } from 'nodemailer';
+
+export interface MailerSendMailOptions extends SendMailOptions {
+	template?: string;
+	context?: any;
+}

lib/mailer.service.spec.ts

@@ -0,0 +1,195 @@
+import { Test, TestingModule } from "@nestjs/testing";
+import MailMessage = require('nodemailer/lib/mailer/mail-message');
+import SMTPTransport = require('nodemailer/lib/smtp-transport');
+import { MAILER_OPTIONS } from "./constants/mailer-options.constant";
+import { MailerOptions } from "./interfaces/mailer-options.interface";
+import { MailerService } from "./mailer.service";
+import { HandlebarsAdapter } from './adapters/handlebars.adapter';
+import { PugAdapter } from './adapters/pug.adapter';
+
+/**
+ * Common testing code for testing up a testing module and MailerService
+ */
+async function getMailerServiceForOptions(
+  options: MailerOptions
+): Promise<MailerService> {
+  const module: TestingModule = await Test.createTestingModule({
+    providers: [
+      {
+        name: MAILER_OPTIONS,
+        provide: MAILER_OPTIONS,
+        useValue: options
+      },
+      MailerService
+    ]
+  }).compile();
+
+  const service = module.get<MailerService>(MailerService);
+
+  return service;
+}
+
+/**
+ * Common testing code for spying on the SMTPTransport's send() implementation
+ */
+function spyOnSmtpSend(onMail: (mail: MailMessage) => void) {
+  return jest.spyOn(SMTPTransport.prototype, 'send').mockImplementation(function (mail: MailMessage, callback: (err: Error | null, info: SMTPTransport.SentMessageInfo) => void): void {
+    onMail(mail);
+    callback(null, {
+      envelope: {
+        from: mail.data.from as string,
+        to: [mail.data.to as string]
+      },
+      messageId: 'ABCD'
+    });
+  });
+}
+
+describe("MailerService", () => {
+  it("should not be defined if a transport is not provided", async () => {
+    await expect(getMailerServiceForOptions({})).rejects.toMatchInlineSnapshot(
+      `[Error: Make sure to provide a nodemailer transport configuration object, connection url or a transport plugin instance.]`
+    );
+  });
+
+  it("should accept a smtp transport string", async () => {
+    const service = await getMailerServiceForOptions({
+      transport: "smtps://[email protected]:[email protected]"
+    });
+
+    expect(service).toBeDefined();
+    expect((service as any).transporter.transporter).toBeInstanceOf(SMTPTransport);
+  });
+
+  it("should accept smtp transport options", async () => {
+    const service = await getMailerServiceForOptions({
+      transport: {
+        secure: true,
+        auth: {
+          user: '[email protected]',
+          pass: 'pass',
+        },
+        options: {
+          host: 'smtp.domain.com',
+        },
+      }
+    });
+
+    expect(service).toBeDefined();
+    expect((service as any).transporter.transporter).toBeInstanceOf(SMTPTransport);
+  });
+
+
+  it("should accept a smtp transport instance", async () => {
+    const transport = new SMTPTransport({})
+    const service = await getMailerServiceForOptions({
+      transport: transport
+    });
+
+    expect(service).toBeDefined();
+    expect((service as any).transporter.transporter).toBe(transport);
+  });
+
+  it('should send emails with nodemailer', async () => {
+    let lastMail: MailMessage;
+    const send = spyOnSmtpSend((mail: MailMessage) => {
+      lastMail = mail;
+    });
+
+    const service = await getMailerServiceForOptions({
+      transport: "smtps://[email protected]:[email protected]"
+    });
+
+    await service.sendMail({
+      from: '[email protected]',
+      to: '[email protected]',
+      subject: 'Test',
+      html: 'This is test.'
+    });
+
+    expect(send).toHaveBeenCalled();
+    expect(lastMail.data.from).toBe('[email protected]');
+    expect(lastMail.data.to).toBe('[email protected]');
+    expect(lastMail.data.subject).toBe('Test');
+    expect(lastMail.data.html).toBe('This is test.');
+  });
+
+  it('should use mailerOptions.defaults when send emails', async () => {
+    let lastMail: MailMessage;
+    const send = spyOnSmtpSend((mail: MailMessage) => {
+      lastMail = mail;
+    });
+
+    const service = await getMailerServiceForOptions({
+      transport: "smtps://[email protected]:[email protected]",
+      defaults: {
+        from: '[email protected]'
+      }
+    });
+
+    await service.sendMail({
+      to: '[email protected]',
+      subject: 'Test',
+      html: 'This is test.'
+    });
+
+    expect(send).toHaveBeenCalled();
+    expect(lastMail.data.from).toBe('[email protected]');
+  });
+
+  it('should compile template with the handlebars adapter', async () => {
+    let lastMail: MailMessage;
+    const send = spyOnSmtpSend((mail: MailMessage) => {
+      lastMail = mail;
+    });
+
+    const service = await getMailerServiceForOptions({
+      transport: new SMTPTransport({}),
+      template: {
+        adapter: new HandlebarsAdapter(),
+      }
+    });
+
+    await service.sendMail({
+      from: '[email protected]',
+      to: '[email protected]',
+      subject: 'Test',
+      template: __dirname + '/test-templates/handlebars-template',
+      context: {
+        world: 'World',
+      },
+    });
+
+    expect(send).toHaveBeenCalled();
+    expect(lastMail.data.from).toBe('[email protected]');
+    expect(lastMail.data.html).toBe('<p>Handlebars test template.</p>\n<p>Hello World!</p>\n');
+  });
+
+  it('should compile template with the pug adapter', async () => {
+    let lastMail: MailMessage;
+    const send = spyOnSmtpSend((mail: MailMessage) => {
+      lastMail = mail;
+    });
+
+    const service = await getMailerServiceForOptions({
+      transport: new SMTPTransport({}),
+      template: {
+        adapter: new PugAdapter(),
+      }
+    });
+
+    await service.sendMail({
+      from: '[email protected]',
+      to: '[email protected]',
+      subject: 'Test',
+      template: __dirname + '/test-templates/pug-template',
+      context: {
+        world: 'World',
+      },
+    });
+
+    expect(send).toHaveBeenCalled();
+    expect(lastMail.data.from).toBe('[email protected]');
+    expect(lastMail.data.html).toBe('<p>Pug test template.</p><p>Hello World!</p>');
+  });
+});

lib/mailer.service.ts

@@ -1,7 +1,8 @@
 /** Dependencies **/
 import { get } from 'lodash';
 import { Injectable, Inject } from '@nestjs/common';
-import { createTransport, SentMessageInfo, Transporter, SendMailOptions } from 'nodemailer';
+import { createTransport, SentMessageInfo, Transporter } from 'nodemailer';
+import { MailerSendMailOptions } from './interfaces/mailer-send-mail-options.interface';
 
 /** Constants **/
 import { MAILER_OPTIONS } from './constants/mailer-options.constant';
@@ -36,7 +37,7 @@ export class MailerService {
     }
   }
 
-  public async sendMail(sendMailOptions: SendMailOptions): Promise<SentMessageInfo> {
+  public async sendMail(sendMailOptions: MailerSendMailOptions): Promise<SentMessageInfo> {
     return await this.transporter.sendMail(sendMailOptions);
   }
 }

lib/test-templates/handlebars-template.hbs

@@ -0,0 +1,2 @@
+<p>Handlebars test template.</p>
+<p>Hello {{world}}!</p>

lib/test-templates/pug-template.pug

@@ -0,0 +1,2 @@
+p Pug test template.
+p= "Hello " + world + "!"