feat(test): diagnose failed effect assertions

examples/html_examples/src/main.rs

@@ -856,10 +856,10 @@ mod tests {
         );
         // Component-level rendering now lowers contact_card-local handles, so the
         // effect contains the lowered handle id, not the source name.
-        assert!(edit.updates_html_containing(
+        edit.assert_updates_html_containing(
             gallery::contact_card,
             &format!("data-hid=\"{}\"", contact_card::save_contact),
-        ));
+        );
 
         let save = inspect_batch(
             InteractionRequest::from(form(
@@ -871,7 +871,7 @@ mod tests {
             .unwrap()
             .batch,
         );
-        assert!(save.updates_html_containing(gallery::contact_card, "ada@hemx.test"));
+        save.assert_updates_html_containing(gallery::contact_card, "ada@hemx.test");
 
         let lazy = inspect_batch(
             InteractionRequest::from(form(gallery::lazy_load, &[("request", "lazy")]))