fix cookie -- not working

internal/prestashop/config/config_test.go

@@ -0,0 +1,19 @@
+package config
+
+import (
+	"crypto/md5"
+	"fmt"
+	"testing"
+)
+
+func TestDeriveCookieNameMatchesFallbackPrestashopRule(t *testing.T) {
+	cfg := Config{PrestaShopVersion: "1.7.3"}
+
+	got := cfg.DeriveCookieName("localhost")
+	sum := md5.Sum([]byte("1.7.3" + "ps-s1"))
+	want := fmt.Sprintf("PrestaShop-%x", sum)
+
+	if got != want {
+		t.Fatalf("DeriveCookieName() = %q, want %q", got, want)
+	}
+}