[Vue] wait for vue to flush queue in waitForNetworkIdle() to reduce UI test random failures (#18853)

* wait for queued vue logic if any in waitForNetworkIdle to reduce rate of random failures

* only do if vue is available

1 files changed, 10 insertions, 1 deletions

diff --git a/tests/lib/screenshot-testing/support/page-renderer.js b/tests/lib/screenshot-testing/support/page-renderer.js
index 1564fe225e..e08da577b8 100644
--- a/tests/lib/screenshot-testing/support/page-renderer.js
+++ b/tests/lib/screenshot-testing/support/page-renderer.js
@@ -305,7 +305,16 @@ PageRenderer.prototype.waitForNetworkIdle = async function () {
         await new Promise(resolve => setTimeout(resolve, AJAX_IDLE_THRESHOLD));
     }
 
-    await this.waitForLazyImages()
+    await this.waitForLazyImages();
+
+    // wait for any queued vue logic
+    await this.webpage.evaluate(function () {
+        if (window.Vue) {
+          return window.Vue.nextTick(function () {
+              // wait
+          });
+        }
+    });
 };
 
 PageRenderer.prototype.waitForLazyImages = async function () {