diff --git a/resources/tester/helper_349_drainage_live_flow.cjs b/resources/tester/helper_349_drainage_live_flow.cjs
index 894f40bcc..55c7f7cd3 100644
--- a/resources/tester/helper_349_drainage_live_flow.cjs
+++ b/resources/tester/helper_349_drainage_live_flow.cjs
@@ -34,6 +34,9 @@ function el(tag) {
     replaceChildren(...kids) {
       this.children = kids;
     },
+    setAttribute(name, value) {
+      (this.attrs ??= {})[name] = String(value);
+    },
     addEventListener(type, fn) {
       (this.listeners[type] ??= []).push(fn);
     },
diff --git a/resources/tester/helper_510_propose.cjs b/resources/tester/helper_510_propose.cjs
index 539268144..ad3608fe1 100644
--- a/resources/tester/helper_510_propose.cjs
+++ b/resources/tester/helper_510_propose.cjs
@@ -24,6 +24,9 @@ function el(tag) {
       node.children = [];
       node.append(...items);
     },
+    setAttribute(name, value) {
+      (this.attrs ??= {})[name] = String(value);
+    },
     addEventListener(type, fn) {
       (listeners[type] ??= []).push(fn);
     },