feat: Expose API to Wait For UI Thread (#864)

README.md

@@ -1121,6 +1121,12 @@ Lists all the previously registered [idling resources](https://developer.android
 
 List of fully qualified class names of currently registered idling resources or an empty list if no resources have been registered yet.
 
+### mobile: waitForUIThread
+
+- Wait for the UI thread to become idle, in other words, wait for the APP to become idle(https://developer.android.com/reference/androidx/test/espresso/UiController#loopMainThreadUntilIdle()). 
+- Use case: On compose and native combination screens, it's possible for the Espresso API to block the UI thread, which can cause the app to freeze. To resolve this issue, it's recommended to explicitly call the `mobile:waitForUIThread` API, which can help to unfreeze the UI thread.
+
+
 ### mobile: unlock
 
 Unlocks the device if it is locked. Noop if the device's screen is not locked.

espresso-server/app/src/androidTest/java/io/appium/espressoserver/lib/handlers/UIThreadSynchronizer.kt

@@ -0,0 +1,36 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * See the NOTICE file distributed with this work for additional
+ * information regarding copyright ownership.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.appium.espressoserver.lib.handlers
+
+import androidx.test.espresso.UiController
+import io.appium.espressoserver.lib.handlers.exceptions.AppiumException
+import io.appium.espressoserver.lib.model.AppiumParams
+import io.appium.espressoserver.lib.viewaction.UiControllerPerformer
+import io.appium.espressoserver.lib.viewaction.UiControllerRunnable
+
+class UIThreadSynchronizer : RequestHandler<AppiumParams, Void?> {
+    override fun handleInternal(params: AppiumParams): Void? {
+        val runnable = object : UiControllerRunnable<Void?> {
+            override fun run(uiController: UiController): Void? {
+                uiController.loopMainThreadUntilIdle()
+                return null
+            }
+        }
+
+        return UiControllerPerformer(runnable).run()
+    }
+}

espresso-server/app/src/androidTest/java/io/appium/espressoserver/lib/http/Router.kt

@@ -143,6 +143,8 @@ internal class Router {
         routeMap.addRoute(RouteDefinition(Method.POST, "/session/:sessionId/appium/execute_mobile/register_idling_resources", RegisterIdlingResources(), IdlingResourcesParams::class.java))
         routeMap.addRoute(RouteDefinition(Method.POST, "/session/:sessionId/appium/execute_mobile/unregister_idling_resources", UnregisterIdlingResources(), IdlingResourcesParams::class.java))
         routeMap.addRoute(RouteDefinition(Method.GET, "/session/:sessionId/appium/execute_mobile/list_idling_resources", ListIdlingResources(), AppiumParams::class.java))
+        routeMap.addRoute(RouteDefinition(Method.POST, "/session/:sessionId/appium/execute_mobile/ui_thread_sync", UIThreadSynchronizer(), AppiumParams::class.java))
+
 
         // Not implemented
         routeMap.addRoute(RouteDefinition(Method.POST, "/session/:sessionId/touch/flick", NotYetImplemented(), AppiumParams::class.java))

lib/commands/execute.js

@@ -73,6 +73,7 @@ extensions.executeMobile = async function executeMobile (mobileCommand, opts = {
     registerIdlingResources: 'mobileRegisterIdlingResources',
     unregisterIdlingResources: 'mobileUnregisterIdlingResources',
     listIdlingResources: 'mobileListIdlingResources',
+    waitForUIThread: 'mobileWaitForUIThread',
 
     unlock: 'mobileUnlock',
 

lib/commands/idling-resources.js

@@ -48,5 +48,12 @@ commands.mobileListIdlingResources = async function mobileListIdlingResources ()
   return await this.espresso.jwproxy.command('/appium/execute_mobile/list_idling_resources', 'GET');
 };
 
+/**
+ * Wait for UI thread to be idle.
+ */
+commands.mobileWaitForUIThread = async function mobileWaitForUIThread () {
+  return await this.espresso.jwproxy.command('/appium/execute_mobile/ui_thread_sync', 'POST');
+};
+
 export { commands };
 export default commands;