add builder 'replace' button specs

spec/request_helper.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module RequestHelper
+  module_function
+
+  def wait_for_fetch
+    page.execute_script(
+      <<~JS
+        if (!window.fetchInitialized) {
+          window.pendingFetchCount = 0;
+
+          const originalFetch = window.fetch;
+
+          window.fetch = function(...args) {
+            window.pendingFetchCount++;
+
+            return originalFetch.apply(this, args).finally(() => {
+              window.pendingFetchCount--;
+            });
+          };
+
+          window.fetchInitialized = true;
+        }
+      JS
+    )
+
+    yield
+
+    Timeout.timeout(Capybara.default_max_wait_time) do
+      loop do
+        break if page.evaluate_script('window.pendingFetchCount') == 0
+
+        sleep 0.1
+      end
+    end
+  end
+end