nuntius/internal/email/acknowledgement_test.go

// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

//go:build linux || freebsd

package email

import (
	"strings"
	"testing"

	"sourcedock.dev/petrbalvin/nuntius/internal/config"
)

func ackForm() *config.Form {
	return &config.Form{
		Name:          "contact",
		Type:          "contact",
		To:            "owner@example.com",
		From:          "noreply@example.com",
		SubjectPrefix: new("nuntius"),
		EmailBrand:    new("nuntius"),
	}
}

func TestComposeAcknowledgement(t *testing.T) {
	msg, err := composeAcknowledgement(ackForm(), "jane@example.com")
	if err != nil {
		t.Fatalf("compose: %v", err)
	}
	raw := string(msg)

	for _, want := range []string{
		"From: noreply@example.com\r\n",
		"To: jane@example.com\r\n",
		"Subject: [nuntius/contact] Message received\r\n",
		// The reply lands in the owner's inbox, not in the void.
		"Reply-To: owner@example.com\r\n",
		"Content-Type: multipart/alternative; boundary=nuntius-",
		"your message to contact was received",
		"Delivered by nuntius",
	} {
		if !strings.Contains(raw, want) {
			t.Errorf("message missing %q", want)
		}
	}
	// The submitted values are deliberately never echoed back.
	if strings.Contains(raw, "jane@example.com\r\n\r\n") && strings.Count(raw, "jane@example.com") != 1 {
		t.Errorf("message echoes the submitter context beyond the To header")
	}
}

func TestComposeAcknowledgementHeaderInjection(t *testing.T) {
	msg, err := composeAcknowledgement(ackForm(), "jane@example.com\r\nBcc: victim@example.com")
	if err != nil {
		t.Fatalf("compose: %v", err)
	}
	raw := string(msg)
	// The whole string collapses into one To header line: no line starts
	// with the injected header name.
	for line := range strings.SplitSeq(raw, "\r\n") {
		if strings.HasPrefix(line, "Bcc:") {
			t.Errorf("a CR/LF in the recipient injected a header line %q", line)
		}
	}
	if !strings.Contains(raw, "To: jane@example.com  Bcc: victim@example.com\r\n") {
		t.Errorf("the CR/LF was not neutralised into spaces")
	}
}

func TestComposeAcknowledgementSubjectWithoutPrefix(t *testing.T) {
	form := ackForm()
	form.SubjectPrefix = new("")
	msg, err := composeAcknowledgement(form, "jane@example.com")
	if err != nil {
		t.Fatalf("compose: %v", err)
	}
	if !strings.Contains(string(msg), "Subject: Message received\r\n") {
		t.Errorf("subject with an empty prefix = %q, want the bare subject", subjectOf(t, string(msg)))
	}
}

func subjectOf(t *testing.T, raw string) string {
	t.Helper()
	for line := range strings.SplitSeq(raw, "\r\n") {
		if after, ok := strings.CutPrefix(line, "Subject: "); ok {
			return after
		}
	}
	t.Fatalf("no subject line in message")
	return ""
}