@eclass/nodemailer-mock

Mocked nodemailer module for unit testing.

install

npm install @eclass/nodemailer-mock --save-dev

yarn add -D @eclass/nodemailer-mock

mock api

There are some special methods available on the mocked module to help with testing.

• nodemailerMock.mock.reset()
  • resets the mock class to default values
• nodemailerMock.mock.sentMail()
  • returns an array of sent emails
• nodemailerMock.mock.shouldFailOnce()
  • will return an error on the next call to transport.sendMail()
• nodemailerMock.mock.shouldFail(true|false)
  • indicate if errors should be returned for subsequent calls to transport.sendMail()
    • if true, return error
    • if false, return success
• nodemailerMock.mock.mockedVerify(true|false)
  • determine if a call to transport.verify() should be mocked or passed through to nodemailer
    • if true, use a mocked callback
    • if false, pass through to a real nodemailer transport
• nodemailerMock.mock.successResponse(success)
  • set the success message that is returned in the callback for transport.sendMail()
• nodemailerMock.mock.failResponse(err)
  • set the err that is returned in the callback for transport.sendMail()

usage

The mocked module behaves in a similar fashion to other transports provided by nodemailer.

const nodemailerMock = require('@eclass/nodemailer-mock');
const transport = nodemailerMock.createTransport();

// the email you want to send
const email = ... // <-- your email here

// send an email with nodestyle callback
transport.sendMail(email, function(err, info) {
  if (err) {
    console.log('Error!', err, info);
  } else {
    console.log('Success!', info);
  }
}

// send an email with promises
transport.sendMail(email)
.then(function(info) {
  console.log('Success!', info);
})
.catch(function(err) {
  console.log('Error!', err);
});

// verify a transport
transport.verify(function(err, success) {
  if (err) {
    console.log('Error!', err);
  } else {
    console.log('Success!', success);
  }
})

example using mocha and mockery

Here is an example of using a mocked nodemailer class in a mocha test using mockery. Make sure that any modules that require()'s a mocked module must be called AFTER the module is mocked or node will use the unmocked version from the module cache.

const should = require('should');
const mockery = require('mockery');
const nodemailerMock = require('@eclass/nodemailer-mock');

describe('Tests that send email', function() {

  /* This could be an app, Express, etc. It should be 
  instantiated *after* nodemailer is mocked. */
  let app = null;

  before(function() {
    // Enable mockery to mock objects
    mockery.enable({
      warnOnUnregistered: false,
    });
    
    /* Once mocked, any code that calls require('nodemailer') 
    will get our nodemailerMock */
    mockery.registerMock('nodemailer', nodemailerMock)
    
    /*
    ##################
    ### IMPORTANT! ###
    ##################
    */
    /* Make sure anything that uses nodemailer is loaded here, 
    after it is mocked just above... */

  });
  
  afterEach(function() {
    // Reset the mock back to the defaults after each test
    nodemailerMock.mock.reset();
  });
  
  after(function() {
    // Remove our mocked nodemailer and disable mockery
    mockery.deregisterAll();
    mockery.disable();
  });
  
  it('should send an email using nodemailer-mock', function(done) {
    // call a service that uses nodemailer
    var response = ... // <-- your email code here
    
    // a fake test for something on our response
    response.value.should.be.exactly('value');
    
    // get the array of emails we sent
    const sentMail = nodemailerMock.mock.sentMail();
    
    // we should have sent one email
    sentMail.length.should.be.exactly(1);
    
    // check the email for something
    sentMail[0].property.should.be.exactly('foobar');
    
    done();
  });
  
  it('should fail to send an email using nodemailer-mock', function(done) {
    // tell the mock class to return an error
    const err = 'My custom error';
    nodemailerMock.mock.shouldFailOnce();
    nodemailerMock.mock.failResponse(err);
  
    // call a service that uses nodemailer
    var response = ... // <-- your code here
    
    // a fake test for something on our response
    response.error.should.be.exactly(err);
    
    done();
  });
  
  it('should verify using the real nodemailer transport', function(done) {
    // tell the mock class to pass verify requests to nodemailer
    nodemailerMock.mock.mockedVerify(false);
  
    // call a service that uses nodemailer
    var response = ... // <-- your code here
    
    /* calls to transport.verify() will be passed through, 
       transport.sendMail() is still mocked */

    done();
  });
});