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nuntius/internal/email/sender_test.go
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT
//go:build linux || freebsd
package email
import (
"bufio"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"fmt"
"math/big"
"net"
"net/smtp"
"strconv"
"strings"
"testing"
"time"
"sourcedock.dev/petrbalvin/nuntius/internal/config"
"sourcedock.dev/petrbalvin/nuntius/internal/contactform"
)
// mustCompose wraps compose for tests: a composition failure is always a
// bug, not a case worth branching on. The bare form carries no policy
// keys, so the composition defaults apply.
func mustCompose(t *testing.T, from, to string, req contactform.Request, formName, formType string) []byte {
t.Helper()
b, err := compose(from, to, req, &config.Form{Name: formName, Type: formType})
if err != nil {
t.Fatalf("compose: %v", err)
}
return b
}
func TestComposeContactWithoutService(t *testing.T) {
req := contactform.Request{
Name: "Alice",
Email: "alice@example.com",
Message: "I have a question about your services.",
}
b := mustCompose(t, "from@example.com", "to@example.com", req, "MyForm", "contact")
s := string(b)
if !strings.Contains(s, "Subject: [nuntius/MyForm] Contact form submission") {
t.Errorf("expected subject with form name only, got body:\n%s", s)
}
if !strings.Contains(s, "From: from@example.com") {
t.Error("expected From header")
}
if !strings.Contains(s, "To: to@example.com") {
t.Error("expected To header")
}
if !strings.Contains(s, "Reply-To: alice@example.com") {
t.Error("expected Reply-To header")
}
if !strings.Contains(s, "MIME-Version: 1.0") {
t.Error("expected MIME-Version header")
}
if !strings.Contains(s, "Content-Type: text/plain; charset=UTF-8") {
t.Error("expected text/plain part")
}
if !strings.Contains(s, "Content-Type: text/html; charset=UTF-8") {
t.Error("expected text/html part")
}
if !strings.Contains(s, "Content-Type: multipart/alternative") {
t.Error("expected multipart/alternative content type")
}
if !strings.Contains(s, "I have a question about your services.") {
t.Error("expected message content in body")
}
if !strings.Contains(s, "Contact Form Submission:") {
t.Error("expected contact form plain-text header")
}
}
func TestComposeContactWithService(t *testing.T) {
req := contactform.Request{
Name: "Bob",
Email: "bob@example.com",
Service: "architecture",
Message: "I would like a consultation.",
}
b := mustCompose(t, "from@e.com", "to@e.com", req, "ContactForm", "contact")
s := string(b)
if !strings.Contains(s, "Subject: [nuntius/ContactForm][architecture] Contact form submission") {
t.Errorf("expected subject with service tag, got body:\n%s", s)
}
if !strings.Contains(s, "Service interest: architecture") {
t.Error("expected service interest in plain text")
}
if !strings.Contains(s, "Content-Type: text/plain") {
t.Error("expected text/plain part")
}
if !strings.Contains(s, "Content-Type: text/html") {
t.Error("expected text/html part")
}
if !strings.Contains(s, "bob@example.com") {
t.Error("expected submitter email in body")
}
}
func TestComposeFeedback(t *testing.T) {
req := contactform.Request{
Name: "Carol",
Email: "carol@example.com",
Message: "Great platform, but can you add dark mode?",
}
b := mustCompose(t, "sender@h.com", "recv@h.com", req, "FeedbackForm", "feedback")
s := string(b)
if !strings.Contains(s, "Subject: [nuntius/FeedbackForm] New feedback") {
t.Errorf("expected feedback subject, got body:\n%s", s)
}
if !strings.Contains(s, "New Feedback:") {
t.Error("expected feedback plain-text header")
}
if !strings.Contains(s, "From: Carol <carol@example.com>") {
t.Error("expected From line in plain text")
}
if !strings.Contains(s, "Content-Type: text/plain") {
t.Error("expected text/plain part")
}
if !strings.Contains(s, "Content-Type: text/html") {
t.Error("expected text/html part")
}
}
func TestComposeNewsletter(t *testing.T) {
req := contactform.Request{
Email: "subscriber@example.com",
}
b := mustCompose(t, "news@h.com", "owner@h.com", req, "NewsletterSignup", "newsletter")
s := string(b)
if !strings.Contains(s, "Subject: [nuntius/NewsletterSignup] New newsletter subscriber") {
t.Errorf("expected newsletter subject, got body:\n%s", s)
}
if !strings.Contains(s, "New Newsletter Subscriber:") {
t.Error("expected newsletter plain-text header")
}
if !strings.Contains(s, "Email: subscriber@example.com") {
t.Error("expected subscriber email in plain text")
}
if !strings.Contains(s, "Content-Type: text/plain") {
t.Error("expected text/plain part")
}
if !strings.Contains(s, "Content-Type: text/html") {
t.Error("expected text/html part")
}
}
func TestComposeGeneric(t *testing.T) {
req := contactform.Request{
Name: "Dave",
Email: "dave@example.com",
Message: "Generic inquiry.",
}
b := mustCompose(t, "g@h.com", "g@h.com", req, "GenericForm", "generic")
s := string(b)
if !strings.Contains(s, "Subject: [nuntius/GenericForm] New submission") {
t.Errorf("expected generic subject, got body:\n%s", s)
}
if !strings.Contains(s, "New Submission:") {
t.Error("expected generic plain-text header")
}
if !strings.Contains(s, "Content-Type: text/plain") {
t.Error("expected text/plain part")
}
if !strings.Contains(s, "Content-Type: text/html") {
t.Error("expected text/html part")
}
}
func TestComposeEmptyFormNameAndEmail(t *testing.T) {
req := contactform.Request{
Name: "",
Email: "",
Message: "",
}
b := mustCompose(t, "", "", req, "", "generic")
s := string(b)
if !strings.Contains(s, "Subject: [nuntius/] New submission") {
t.Errorf("expected subject with empty form name, got body:\n%s", s)
}
if !strings.Contains(s, "MIME-Version: 1.0") {
t.Error("expected MIME-Version header even with empty fields")
}
if !strings.Contains(s, "Content-Type: text/plain") {
t.Error("expected text/plain part even with empty fields")
}
if !strings.Contains(s, "Content-Type: text/html") {
t.Error("expected text/html part even with empty fields")
}
}
func TestComposeLongMessage(t *testing.T) {
longMsg := strings.Repeat("Lorem ipsum dolor sit amet. ", 200)
req := contactform.Request{
Name: "Eve",
Email: "eve@example.com",
Message: longMsg,
}
b := mustCompose(t, "x@y.com", "z@y.com", req, "LongForm", "feedback")
s := string(b)
if !strings.Contains(s, longMsg) {
t.Error("expected long message content in body")
}
// Verify it's in both text and html parts by checking after the respective
// content-type boundaries.
textIdx := strings.Index(s, "Content-Type: text/plain")
htmlIdx := strings.Index(s, "Content-Type: text/html")
if textIdx == -1 || htmlIdx == -1 {
t.Fatal("expected both text/plain and text/html parts")
}
textPart := s[textIdx:htmlIdx]
htmlPart := s[htmlIdx:]
if !strings.Contains(textPart, longMsg) {
t.Error("expected long message in text/plain part")
}
if !strings.Contains(htmlPart, longMsg) {
t.Error("expected long message in text/html part")
}
}
func TestComposeSpecialCharacters(t *testing.T) {
specialMsg := "Café résumé, déjà vu\nLine\twith\ttabs\n€uro sign © 2026"
req := contactform.Request{
Name: "Renée",
Email: "renée@example.com",
Message: specialMsg,
}
b := mustCompose(t, "ñ@c.com", "ö@c.com", req, "SpaForm", "contact")
s := string(b)
if !strings.Contains(s, "Café résumé, déjà vu") {
t.Error("expected accented characters to survive round-trip")
}
if !strings.Contains(s, "€uro sign © 2026") {
t.Error("expected special symbols to survive round-trip")
}
if !strings.Contains(s, "Renée") {
t.Error("expected accented name in body")
}
if !strings.Contains(s, "MIME-Version: 1.0") {
t.Error("expected MIME-Version header")
}
}
func TestComposeUnknownFormTypeFallsBackToContact(t *testing.T) {
// Unknown form type should default to the contact template.
req := contactform.Request{
Name: "Fallback",
Email: "fallback@example.com",
Message: "Does this work?",
}
b := mustCompose(t, "a@b.com", "c@b.com", req, "UnknownForm", "nonexistent")
s := string(b)
if !strings.Contains(s, "Subject: [nuntius/UnknownForm] Contact form submission") {
t.Errorf("expected contact fallback subject, got body:\n%s", s)
}
if !strings.Contains(s, "Content-Type: text/plain") {
t.Error("expected text/plain part in fallback")
}
if !strings.Contains(s, "Content-Type: text/html") {
t.Error("expected text/html part in fallback")
}
}
func TestComposeAllHeadersPresent(t *testing.T) {
req := contactform.Request{
Name: "Test",
Email: "test@example.com",
Message: "Checking headers.",
}
b := mustCompose(t, "from@x.com", "to@x.com", req, "HeaderForm", "contact")
s := string(b)
required := []string{
"From: from@x.com",
"To: to@x.com",
"Subject:",
"Date:",
"Reply-To: test@example.com",
"MIME-Version: 1.0",
"Content-Type: multipart/alternative",
}
for _, h := range required {
if !strings.Contains(s, h) {
t.Errorf("expected header %q in message", h)
}
}
}
func TestComposeMultipartBoundary(t *testing.T) {
req := contactform.Request{
Name: "Boundary",
Email: "boundary@example.com",
Message: "Boundary test.",
}
b := mustCompose(t, "from@t.com", "to@t.com", req, "BoundForm", "contact")
s := string(b)
// The boundary is random per message; verify structure, not a fixed value.
if !strings.Contains(s, "Content-Type: multipart/alternative; boundary=nuntius-") {
t.Error("expected multipart/alternative with nuntius- prefixed boundary")
}
// Extract the boundary token and verify opening, middle and closing markers.
idx := strings.Index(s, "boundary=nuntius-")
if idx == -1 {
t.Fatal("boundary token not found")
}
boundary := s[idx+len("boundary="):]
if end := strings.IndexByte(boundary, '\r'); end >= 0 {
boundary = boundary[:end]
}
if count := strings.Count(s, "--"+boundary); count < 3 {
t.Errorf("expected at least 3 boundary markers for %q, got %d", boundary, count)
}
if !strings.Contains(s, "--"+boundary+"--") {
t.Error("expected closing boundary marker")
}
}
func TestComposeDeliveredByFooter(t *testing.T) {
req := contactform.Request{
Name: "Footer",
Email: "footer@example.com",
Message: "Footer check.",
}
for _, ft := range []string{"contact", "feedback", "newsletter", "generic"} {
b := mustCompose(t, "f@t.com", "t@t.com", req, "FooterForm", ft)
s := string(b)
if !strings.Contains(s, "Delivered by nuntius") {
t.Errorf("form type %q: expected 'Delivered by nuntius' footer in plain text", ft)
}
}
}
// A configured subject prefix and brand replace the default nuntius
// wording in both the plain-text and the HTML part.
func TestComposePrefixAndBrand(t *testing.T) {
req := contactform.Request{
Name: "Alice",
Email: "alice@example.com",
Message: "A custom branding check.",
}
form := &config.Form{
Name: "MyForm",
Type: "feedback",
SubjectPrefix: new("web"),
EmailBrand: new("Acme Mail"),
}
b, err := compose("from@example.com", "to@example.com", req, form)
if err != nil {
t.Fatalf("compose: %v", err)
}
s := string(b)
if !strings.Contains(s, "Subject: [web/MyForm] New feedback") {
t.Errorf("configured prefix missing from subject:\n%s", s)
}
if !strings.Contains(s, "Delivered by Acme Mail") {
t.Error("configured brand missing from the plain-text footer")
}
if !strings.Contains(s, "Delivered by <strong style=\"color:#6b7280\">Acme Mail</strong>") {
t.Error("configured brand missing from the HTML footer")
}
// An empty prefix and brand drop the segments entirely.
form.SubjectPrefix = new("")
form.EmailBrand = new("")
b, err = compose("from@example.com", "to@example.com", req, form)
if err != nil {
t.Fatalf("compose: %v", err)
}
s = string(b)
if !strings.Contains(s, "Subject: New feedback\r\n") {
t.Errorf("empty prefix must drop the bracket segment:\n%s", s)
}
if strings.Contains(s, "Delivered by") {
t.Errorf("empty brand must drop the footer:\n%s", s)
}
}
// A service value configured onto a non-contact form surfaces in the
// subject tag, the plain-text body and the HTML body.
func TestComposeServiceOnFeedback(t *testing.T) {
req := contactform.Request{
Name: "Alice",
Email: "alice@example.com",
Service: "bug",
Message: "A service-aware feedback.",
}
form := &config.Form{
Name: "MyForm",
Type: "feedback",
Services: []string{"bug", "idea"},
}
b, err := compose("from@example.com", "to@example.com", req, form)
if err != nil {
t.Fatalf("compose: %v", err)
}
s := string(b)
if !strings.Contains(s, "Subject: [nuntius/MyForm][bug] New feedback") {
t.Errorf("service tag missing from subject:\n%s", s)
}
if !strings.Contains(s, "Service interest: bug") {
t.Error("service line missing from the plain-text body")
}
if !strings.Contains(s, "Service Interest") {
t.Error("service block missing from the HTML body")
}
}
// ---------------------------------------------------------------------------
// SMTP delivery tests
// ---------------------------------------------------------------------------
func selfSignedCert(t *testing.T) tls.Certificate {
t.Helper()
priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
t.Fatalf("generate key: %v", err)
}
tmpl := x509.Certificate{
SerialNumber: big.NewInt(1),
Subject: pkix.Name{CommonName: "localhost"},
NotBefore: time.Now().Add(-time.Hour),
NotAfter: time.Now().Add(time.Hour),
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
IPAddresses: []net.IP{net.ParseIP("127.0.0.1")},
}
der, err := x509.CreateCertificate(rand.Reader, &tmpl, &tmpl, &priv.PublicKey, priv)
if err != nil {
t.Fatalf("create certificate: %v", err)
}
return tls.Certificate{Certificate: [][]byte{der}, PrivateKey: priv}
}
// startFakeSMTP runs a minimal SMTP server that supports STARTTLS and AUTH.
// It returns the listen address.
func startFakeSMTP(t *testing.T, cert tls.Certificate) string {
t.Helper()
ln, err := net.Listen("tcp", "127.0.0.1:0")
if err != nil {
t.Fatalf("listen: %v", err)
}
t.Cleanup(func() { ln.Close() })
go func() {
conn, err := ln.Accept()
if err != nil {
return
}
defer conn.Close()
fmt.Fprintf(conn, "220 fake ESMTP\r\n")
reader := bufio.NewReader(conn)
for {
line, err := reader.ReadString('\n')
if err != nil {
return
}
line = strings.TrimSpace(line)
switch {
case strings.HasPrefix(line, "EHLO"), strings.HasPrefix(line, "HELO"):
fmt.Fprintf(conn, "250-fake\r\n250-STARTTLS\r\n250 AUTH PLAIN\r\n")
case strings.HasPrefix(line, "STARTTLS"):
fmt.Fprintf(conn, "220 Ready to start TLS\r\n")
tlsConn := tls.Server(conn, &tls.Config{Certificates: []tls.Certificate{cert}})
if err := tlsConn.Handshake(); err != nil {
return
}
conn = tlsConn
reader = bufio.NewReader(conn)
case strings.HasPrefix(line, "AUTH"):
fmt.Fprintf(conn, "235 Authentication successful\r\n")
case strings.HasPrefix(line, "MAIL FROM:"), strings.HasPrefix(line, "RCPT TO:"):
fmt.Fprintf(conn, "250 OK\r\n")
case strings.HasPrefix(line, "DATA"):
fmt.Fprintf(conn, "354 End data with <CR><LF>.<CR><LF>\r\n")
for {
dataLine, err := reader.ReadString('\n')
if err != nil {
return
}
if strings.TrimSpace(dataLine) == "." {
break
}
}
fmt.Fprintf(conn, "250 OK\r\n")
case strings.HasPrefix(line, "QUIT"):
fmt.Fprintf(conn, "221 Bye\r\n")
return
default:
fmt.Fprintf(conn, "250 OK\r\n")
}
}
}()
return ln.Addr().String()
}
// A validated email may still contain characters that would terminate a
// header line; composition must neutralise them defensively in the header
// block. Body content is free-form and delimited by the random boundary.
func TestComposeSanitisesHeaderInjection(t *testing.T) {
req := contactform.Request{
Name: "Eve",
Email: "eve@example.com",
Message: "Hello there, this is fine.",
}
b := mustCompose(t, "from@example.com", "to@example.com", req,
"Form\r\nBcc: victim@example.com", "contact")
s := string(b)
headers := s[:strings.Index(s, "\r\n\r\n")]
for line := range strings.SplitSeq(headers, "\r\n") {
if strings.HasPrefix(line, "Bcc:") {
t.Errorf("injected Bcc header survived composition:\n%s", s)
}
}
if n := strings.Count(headers, "Subject:"); n != 1 {
t.Errorf("expected exactly one Subject header in block %q, got %d", headers, n)
}
}
func TestRandomBoundary(t *testing.T) {
b1, err := randomBoundary()
if err != nil {
t.Fatalf("randomBoundary: %v", err)
}
b2, err := randomBoundary()
if err != nil {
t.Fatalf("randomBoundary: %v", err)
}
if !strings.HasPrefix(b1, "nuntius-") {
t.Errorf("boundary %q missing nuntius- prefix", b1)
}
if b1 == b2 {
t.Error("two consecutive boundaries should differ")
}
}
func TestSendMailDialError(t *testing.T) {
// Connect to a closed port to trigger a dial error quickly.
err := sendMail(config.SMTPConfig{Host: "127.0.0.1", Port: 1}, nil, "a@b.c", []string{"d@e.f"}, []byte("x"), 100*time.Millisecond, nil)
if err == nil {
t.Fatal("expected dial error")
}
}
func TestSendMailWithTLS(t *testing.T) {
cert := selfSignedCert(t)
addr := startFakeSMTP(t, cert)
host, portStr, err := net.SplitHostPort(addr)
if err != nil {
t.Fatalf("split host: %v", err)
}
port, err := strconv.Atoi(portStr)
if err != nil {
t.Fatalf("parse port: %v", err)
}
auth := smtp.PlainAuth("", "user", "pass", host)
msg := mustCompose(t, "from@example.com", "to@example.com", contactform.Request{
Name: "Test User",
Email: "test@example.com",
Message: "Hello, this is a test message.",
}, "test", "contact")
err = sendMail(config.SMTPConfig{Host: host, Port: port}, auth, "from@example.com", []string{"to@example.com"}, msg, 5*time.Second, &tls.Config{InsecureSkipVerify: true})
if err != nil {
t.Fatalf("sendMail: %v", err)
}
}
func TestFormSenderSend(t *testing.T) {
cert := selfSignedCert(t)
addr := startFakeSMTP(t, cert)
host, portStr, err := net.SplitHostPort(addr)
if err != nil {
t.Fatalf("split host: %v", err)
}
port := 0
for _, c := range portStr {
port = port*10 + int(c-'0')
}
form := &config.Form{
Name: "test",
Type: "contact",
From: "from@example.com",
To: "to@example.com",
SMTP: config.SMTPConfig{
Host: host,
Port: port,
User: "user",
Password: "pass",
},
}
s := NewFormSender(form)
s.TLSConfig = &tls.Config{InsecureSkipVerify: true}
err = s.Send(contactform.Request{
Name: "Test User",
Email: "test@example.com",
Message: "Hello, this is a test message.",
})
if err != nil {
t.Fatalf("Send: %v", err)
}
}