magento-research/pwa-tests#MQE-1382-WaitForReactPageLoad

- Adding a new action for waitForReactPageLoad to the schema.
- Adding basic structure for the new action to the MagentoWebDriver.

Author: ivy00johns

src/Magento/FunctionalTestingFramework/Module/MagentoWebDriver.php

@@ -379,6 +379,21 @@ public function waitForPageLoad($timeout = null)
         $this->waitForLoadingMaskToDisappear($timeout);
     }
 
+    /**
+     * Wait for all React JavaScript to finish executing.
+     *
+     * @param integer $timeout
+     * @throws \Exception
+     * @return void
+     */
+    public function waitForReactPageLoad($timeout = null)
+    {
+        $timeout = $timeout ?? $this->_getConfig()['pageload_timeout'];
+
+        $this->waitForJS('return (!!Object.keys(document).filter(prop => /^_reactListenersID/.test(prop)).length) || (document.querySelector("[data-reactroot]") && Object.keys(rootEl).some(prop => /^__reactInternalInstance/.test(prop)));', $timeout);
+        $this->waitForJS("return document.readyState == 'complete';", $timeout);
+    }
+
     /**
      * Wait for all visible loading masks to disappear. Gets all elements by mask selector, then loops over them.
      *

src/Magento/FunctionalTestingFramework/Test/etc/Actions/waitActions.xsd

@@ -20,6 +20,7 @@
             <xs:element type="waitForJSType" name="waitForJS" minOccurs="0" maxOccurs="unbounded"/>
             <xs:element type="waitForLoadingMaskToDisappearType" name="waitForLoadingMaskToDisappear" minOccurs="0" maxOccurs="unbounded"/>
             <xs:element type="waitForPageLoadType" name="waitForPageLoad" minOccurs="0" maxOccurs="unbounded"/>
+            <xs:element type="waitForReactPageLoadType" name="waitForReactPageLoad" minOccurs="0" maxOccurs="unbounded"/>
             <xs:element type="waitForTextType" name="waitForText" minOccurs="0" maxOccurs="unbounded"/>
         </xs:choice>
     </xs:group>
@@ -176,6 +177,20 @@
         </xs:simpleContent>
     </xs:complexType>
 
+    <xs:complexType name="waitForReactPageLoadType">
+        <xs:annotation>
+            <xs:documentation>
+                Waits up to given time for React page to have finished loading..
+            </xs:documentation>
+        </xs:annotation>
+        <xs:simpleContent>
+            <xs:extension base="xs:string">
+                <xs:attribute ref="time"/>
+                <xs:attributeGroup ref="commonActionAttributes"/>
+            </xs:extension>
+        </xs:simpleContent>
+    </xs:complexType>
+
     <xs:complexType name="waitForTextType">
         <xs:annotation>
             <xs:documentation>