#18: implement SMTP Submission (587/465), SASL PLAIN/LOGIN auth and preflight diagnostics

services/protocols/internal/application/usecase/inbound_scan_headers_test.go

@@ -0,0 +1,99 @@
+package usecase
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"strings"
+	"testing"
+
+	"github.com/google/uuid"
+
+	"lambdamail/protocols/internal/application/port"
+	"lambdamail/protocols/internal/domain/valueobject"
+)
+
+type capturingBlobStorage struct {
+	stored []byte
+}
+
+func (c *capturingBlobStorage) Store(_ context.Context, r io.Reader) (port.BlobRef, error) {
+	b, err := io.ReadAll(r)
+	c.stored = b
+	return port.BlobRef{ID: uuid.New(), SizeBytes: int64(len(b))}, err
+}
+
+type stubScanner struct {
+	result *valueobject.ScanResult
+}
+
+func (s *stubScanner) Scan(_ context.Context, _ port.ScanInput) (*valueobject.ScanResult, error) {
+	return s.result, nil
+}
+
+// The scan verdict is only actionable by the user - and by their Sieve rules -
+// if it reaches the stored message. PLAN.md section 6.1 persists the EML
+// together with the verdicts, so the spam headers the scanner produced must be
+// present in the delivered message.
+func TestUseCase_Handle_WritesScanHeadersIntoStoredMessage(t *testing.T) {
+	blobs := &capturingBlobStorage{}
+	scanner := &stubScanner{result: &valueobject.ScanResult{
+		Verdict: valueobject.ScanVerdictSpamJunk,
+		Score:   9.5,
+		HeadersToAdd: map[string]string{
+			"X-Spam-Flag":  "YES",
+			"X-Spam-Score": "9.50",
+		},
+	}}
+
+	uc := NewProcessInboundEmailUseCase(nil, blobs, &recordingMessageRepository{})
+	uc.SetScanner(scanner)
+
+	err := uc.Handle(context.Background(), ProcessInboundEmailInput{
+		Sender:             "spammer@example.test",
+		Recipients:         []port.MailboxRecord{{ID: uuid.New()}},
+		RecipientAddresses: []string{"victim@example.test"},
+		Body:               bytes.NewBufferString("Subject: buy now\r\n\r\nbody"),
+	})
+	if err != nil {
+		t.Fatalf("Handle: %v", err)
+	}
+
+	stored := string(blobs.stored)
+	for _, want := range []string{"X-Spam-Flag: YES", "X-Spam-Score: 9.50"} {
+		if !strings.Contains(stored, want) {
+			t.Errorf("stored message is missing %q:\n%s", want, stored)
+		}
+	}
+	if !strings.Contains(stored, "Subject: buy now") {
+		t.Errorf("original headers were lost:\n%s", stored)
+	}
+	// Added headers must precede the original ones and stay inside the header
+	// block, i.e. before the first empty line.
+	headerBlock, _, found := strings.Cut(stored, "\r\n\r\n")
+	if !found {
+		t.Fatalf("stored message has no header/body separator:\n%s", stored)
+	}
+	if !strings.Contains(headerBlock, "X-Spam-Flag: YES") {
+		t.Errorf("scan headers leaked into the body:\n%s", stored)
+	}
+}
+
+func TestUseCase_Handle_LeavesMessageUntouchedWithoutScanHeaders(t *testing.T) {
+	blobs := &capturingBlobStorage{}
+	uc := NewProcessInboundEmailUseCase(nil, blobs, &recordingMessageRepository{})
+
+	original := "Subject: hi\r\n\r\nbody"
+	err := uc.Handle(context.Background(), ProcessInboundEmailInput{
+		Recipients:         []port.MailboxRecord{{ID: uuid.New()}},
+		RecipientAddresses: []string{"a@example.test"},
+		Body:               bytes.NewBufferString(original),
+	})
+	if err != nil {
+		t.Fatalf("Handle: %v", err)
+	}
+
+	if string(blobs.stored) != original {
+		t.Errorf("message was rewritten without a scanner: got %q, want %q", blobs.stored, original)
+	}
+}