1 files changed, 10 insertions, 1 deletions
diff --git a/activestorage/test/controllers/previews_controller_test.rb b/activestorage/test/controllers/previews_controller_test.rb
index c3151a710e..b87be6c8b2 100644
--- a/activestorage/test/controllers/previews_controller_test.rb
+++ b/activestorage/test/controllers/previews_controller_test.rb
@@ -14,11 +14,20 @@ class ActiveStorage::PreviewsControllerTest < ActionDispatch::IntegrationTest
       signed_blob_id: @blob.signed_id,
       variation_key: ActiveStorage::Variation.encode(resize: "100x100"))
 
-    assert @blob.preview_image.attached?
+    assert_predicate @blob.preview_image, :attached?
     assert_redirected_to(/report\.png\?.*disposition=inline/)
 
     image = read_image(@blob.preview_image.variant(resize: "100x100"))
     assert_equal 77, image.width
     assert_equal 100, image.height
   end
+
+  test "showing preview with invalid signed blob ID" do
+    get rails_blob_preview_url(
+      filename: @blob.filename,
+      signed_blob_id: "invalid",
+      variation_key: ActiveStorage::Variation.encode(resize: "100x100"))
+
+    assert_response :not_found
+  end
 end