1 files changed, 25 insertions, 1 deletions
diff --git a/app/controllers/dashboard/controller_test.go b/app/controllers/dashboard/controller_test.go
index ddbfd34..3472565 100644
--- a/app/controllers/dashboard/controller_test.go
+++ b/app/controllers/dashboard/controller_test.go
@@ -1,7 +1,9 @@
 package dashboard
 
 import (
+	"errors"
 	"net/http"
+	"net/http/httptest"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -11,6 +13,22 @@ import (
 	"gitlab.com/gitlab-org/software-supply-chain-security/authorization/sparkled/app/domain"
 )
 
+type FailingResponseWriter struct {
+	*testing.T
+	*httptest.ResponseRecorder
+	headerWritten bool
+}
+
+func (f *FailingResponseWriter) WriteHeader(statusCode int) {
+	require.False(f.T, f.headerWritten)
+	f.headerWritten = true
+	f.ResponseRecorder.WriteHeader(statusCode)
+}
+
+func (f *FailingResponseWriter) Write([]byte) (int, error) {
+	return 0, errors.New("write failed")
+}
+
 func TestController(t *testing.T) {
 	mux := http.NewServeMux()
 	controller := New()
@@ -38,6 +56,13 @@ func TestController(t *testing.T) {
 				assert.Contains(t, w.Body.String(), "<html")
 			})
 		})
+
+		t.Run("prevents double WriteHeader when template rendering fails", func(t *testing.T) {
+			ctx := cfg.CurrentUser.With(t.Context(), &domain.User{ID: domain.ID("1")})
+			request, response := test.RequestResponse("GET", "/dashboard", test.WithContext(ctx))
+
+			controller.Show(&FailingResponseWriter{T: t, ResponseRecorder: response}, request)
+		})
 	})
 
 	t.Run("GET /dashboard/nav", func(t *testing.T) {
@@ -68,5 +93,4 @@ func TestController(t *testing.T) {
 			})
 		})
 	})
-
 }