email-sender/pkg/email/email_test.go

package email

import (
	"crypto/tls"
	"fmt"
	"net/smtp"
	"os"
	"testing"

	"github.com/joho/godotenv"
	"github.com/kelseyhightower/envconfig"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

type config struct {
	MailUser     string `required:"false" split_words:"true"`
	MailPassword string `required:"false" split_words:"true"`
	MailHost     string `required:"false" split_words:"true"`
	MailPort     string `required:"false" split_words:"true"`
	MailFrom     string `required:"false" split_words:"true"`
	MailTo       string `required:"false" split_words:"true"`
}

func newConfig(envFile string) *config {
	if envFile != "" {
		err := godotenv.Load(envFile)
		if err != nil {
			panic(fmt.Errorf("godotenv.Load: %w", err))
		}
	}

	cfg := &config{}
	err := envconfig.Process("", cfg)
	if err != nil {
		panic(fmt.Errorf("envconfig.Process: %w", err))
	}

	return cfg
}

func TestNewConfig_MissingEnvFile(t *testing.T) {
	assert.Panics(t, func() { newConfig(".missing_env_file") })
}

func TestMockSendEmail(t *testing.T) {
	service := &EmailService{
		auth: smtp.PlainAuth("", "", "", ""),
		host: "",
		port: "",
		from: "",
		tlsconfig: &tls.Config{
			InsecureSkipVerify: true,
			ServerName:         "",
		},
		dial: func(hostPort string) (SMTPClientIface, error) {
			return &MockSMTP{}, nil
		},
	}

	emailData := EmailMessage{
		To:      "test@example.com",
		Subject: "Test Email",
		Body:    "This is a test email.",
	}

	err := service.SendEmail(emailData)
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
}

func TestSendEmail(t *testing.T) {
	cfg := newConfig(".env.test")

	mailSrv := NewMailService(MailServiceConfig{
		Auth: smtp.PlainAuth("", cfg.MailUser, cfg.MailPassword, cfg.MailHost),
		Host: cfg.MailHost,
		Port: cfg.MailPort,
		From: cfg.MailFrom,
	})

	data := EmailMessage{
		To:      cfg.MailTo,
		Subject: "Mail Sender",
		Body:    "Hello this is a test email",
	}
	require.NoError(t, mailSrv.SendEmail(data))
}

func TestSendEmail_FailedAuthentication(t *testing.T) {
	cfg := newConfig(".env.test")
	// set up authentication to fail
	mailSrv := NewMailService(MailServiceConfig{
		Auth: smtp.PlainAuth("", "wronguser", "wrongpassword", cfg.MailHost),
		Host: cfg.MailHost,
		Port: cfg.MailPort,
		From: cfg.MailFrom,
	})
	data := EmailMessage{
		To:      cfg.MailTo,
		Subject: "Test Email",
		Body:    "This is a test email.",
	}
	err := mailSrv.SendEmail(data)
	assert.Error(t, err)
}

func TestSendEmail_InvalidRecipient(t *testing.T) {
	cfg := newConfig(".env.test")
	mailSrv := NewMailService(MailServiceConfig{
		Auth: smtp.PlainAuth("", cfg.MailUser, cfg.MailPassword, cfg.MailHost),
		Host: cfg.MailHost,
		Port: cfg.MailPort,
		From: cfg.MailFrom,
	})
	data := EmailMessage{
		To:      "invalid_email",
		Subject: "Test Email",
		Body:    "This is a test email.",
	}
	err := mailSrv.SendEmail(data)
	assert.Error(t, err)
}

func TestSendEmailWithAttachments(t *testing.T) {
	cfg := newConfig(".env.test")

	mailSrv := NewMailService(MailServiceConfig{
		Auth: smtp.PlainAuth("", cfg.MailUser, cfg.MailPassword, cfg.MailHost),
		Host: cfg.MailHost,
		Port: cfg.MailPort,
		From: cfg.MailFrom,
	})
	reader, err := os.Open("testdata/attachment1.txt")
	require.NoError(t, err)
	defer reader.Close()

	reader2, err := os.Open("testdata/attachment2.txt")
	require.NoError(t, err)
	defer reader2.Close()

	reader3, err := os.Open("testdata/attachment3.txt")
	require.NoError(t, err)
	defer reader3.Close()

	data := EmailMessage{
		To:      cfg.MailTo,
		Subject: "Mail Sender",
		Body:    "Hello this is a test email",
		Attachments: []EmailAttachment{
			{
				Title: "attachment1.txt",
				File:  reader,
			},
			{
				Title: "attachment2.txt",
				File:  reader2,
			},
			{
				Title: "attachment3.txt",
				File:  reader3,
			},
		},
	}
	err = mailSrv.SendEmail(data)
	require.NoError(t, err)
}

func TestWithAttachments(t *testing.T) {
	msg := newMessage("from", "to", "subject")
	content, err := msg.withAttachments("body", nil)
	require.NoError(t, err)
	assert.Greater(t, len(content), 0)
}