fix cookie -- not working

internal/prestashop/cookie/codec_test.go

@@ -1,6 +1,11 @@
 package cookie
 
-import "testing"
+import (
+	"fmt"
+	"hash/crc32"
+	"strings"
+	"testing"
+)
 
 const (
 	testCookieKey = "def000008bf3d70e7012b7493c382d561e193218d0c74ab162fb0ea8029ce20e926531b4bcf0aaec9381152e6c161f198e06918b2d1aad67cc7cf40819a51ee328c63830"
@@ -66,3 +71,44 @@ func TestNativeCodecRoundTrip(t *testing.T) {
 		t.Fatalf("plaintext mismatch after roundtrip\n got: %s\nwant: %s", redecoded.Plaintext, decoded.Plaintext)
 	}
 }
+
+func TestNativeCodecEncodeRecomputesPrestashopChecksum(t *testing.T) {
+	codec, err := NewCodec(Config{
+		CookieName: "PrestaShop-test",
+		CookieKey:  testCookieKey,
+		CookieIV:   "vfRFMV42",
+	})
+	if err != nil {
+		t.Fatalf("NewCodec() error = %v", err)
+	}
+
+	decoded, err := codec.Decode(testCookie)
+	if err != nil {
+		t.Fatalf("Decode() error = %v", err)
+	}
+
+	decoded.Values["iso_code_country"] = "PL"
+	decoded.Values["id_currency"] = "6"
+	decoded.Values["checksum"] = "stale"
+	decoded.Plaintext = ""
+
+	encoded, err := codec.Encode(decoded)
+	if err != nil {
+		t.Fatalf("Encode() error = %v", err)
+	}
+
+	redecoded, err := codec.Decode(encoded)
+	if err != nil {
+		t.Fatalf("Decode(encoded) error = %v", err)
+	}
+
+	pairs := strings.Split(redecoded.Plaintext, fieldSeparator)
+	if len(pairs) < 2 {
+		t.Fatalf("plaintext too short: %q", redecoded.Plaintext)
+	}
+	body := strings.Join(pairs[:len(pairs)-1], fieldSeparator) + fieldSeparator
+	wantChecksum := fmt.Sprintf("%d", crc32.ChecksumIEEE([]byte("vfRFMV42"+body)))
+	if got := redecoded.Values["checksum"]; got != wantChecksum {
+		t.Fatalf("checksum = %q, want %q", got, wantChecksum)
+	}
+}