feat(mail): RFC822 message parsing (headers, body, attachments)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/mail/message_test.go

@@ -0,0 +1,70 @@
+package mail
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func loadFixture(t *testing.T, name string) []byte {
+	t.Helper()
+	b, err := os.ReadFile(filepath.Join("testdata", name))
+	if err != nil {
+		t.Fatalf("read fixture: %v", err)
+	}
+	return b
+}
+
+func TestParseMessage(t *testing.T) {
+	raw := loadFixture(t, "with_attachment.eml")
+	m, err := ParseMessage(42, raw)
+	if err != nil {
+		t.Fatalf("ParseMessage: %v", err)
+	}
+	if m.Header.UID != 42 {
+		t.Fatalf("uid: %d", m.Header.UID)
+	}
+	if m.Header.Subject != "Your Invoice #5" {
+		t.Fatalf("subject: %q", m.Header.Subject)
+	}
+	if m.Header.From != `"Bob" <bob@trusted.com>` && m.Header.From != "Bob <bob@trusted.com>" {
+		t.Fatalf("from: %q", m.Header.From)
+	}
+	if m.Header.MessageID != "abc123@trusted.com" && m.Header.MessageID != "<abc123@trusted.com>" {
+		t.Fatalf("message-id: %q", m.Header.MessageID)
+	}
+	if want := "Hello, here is your invoice."; !contains(m.BodyText, want) {
+		t.Fatalf("body=%q want contains %q", m.BodyText, want)
+	}
+	if !m.Header.HasAttachments {
+		t.Fatal("HasAttachments should be true")
+	}
+	if len(m.Attachments) != 1 || m.Attachments[0].Name != "invoice.txt" {
+		t.Fatalf("attachments: %+v", m.Attachments)
+	}
+	if !contains(string(m.Attachments[0].Content), "LINE-ITEM 1") {
+		t.Fatalf("attachment content: %q", m.Attachments[0].Content)
+	}
+}
+
+func TestParseHeaderOnly(t *testing.T) {
+	raw := loadFixture(t, "with_attachment.eml")
+	h, err := ParseHeaderOnly(7, raw)
+	if err != nil {
+		t.Fatalf("ParseHeaderOnly: %v", err)
+	}
+	if h.Subject != "Your Invoice #5" || !h.HasAttachments {
+		t.Fatalf("header: %+v", h)
+	}
+}
+
+func contains(s, sub string) bool {
+	return len(s) >= len(sub) && (func() bool {
+		for i := 0; i+len(sub) <= len(s); i++ {
+			if s[i:i+len(sub)] == sub {
+				return true
+			}
+		}
+		return false
+	}())
+}