fix: accept existing license machine binding (#546)

go-backend/internal/license/keygen_test.go

@@ -0,0 +1,40 @@
+package license
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestActivateMachineTreatsFingerprintTakenAsIdempotent(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusUnprocessableEntity)
+		_, _ = fmt.Fprint(w, `{"errors":[{"code":"FINGERPRINT_TAKEN"},{"code":"MACHINE_LIMIT_EXCEEDED"}]}`)
+	}))
+	defer server.Close()
+
+	client := NewKeygenClient("account-id", "license-key")
+	client.BaseURL = server.URL
+
+	if err := client.ActivateMachine("license-id", "fingerprint"); err != nil {
+		t.Fatalf("ActivateMachine() error = %v, want idempotent success", err)
+	}
+}
+
+func TestActivateMachineRejectsMachineLimitWithoutFingerprintTaken(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusUnprocessableEntity)
+		_, _ = fmt.Fprint(w, `{"errors":[{"code":"MACHINE_LIMIT_EXCEEDED"}]}`)
+	}))
+	defer server.Close()
+
+	client := NewKeygenClient("account-id", "license-key")
+	client.BaseURL = server.URL
+
+	err := client.ActivateMachine("license-id", "fingerprint")
+	if err == nil || !strings.Contains(err.Error(), "MACHINE_LIMIT_EXCEEDED") {
+		t.Fatalf("ActivateMachine() error = %v, want machine limit failure", err)
+	}
+}