Add waitAndFind helper

Change-Id: I7498dda3eb686d15829d89688695866ae8382c6e

benchmarks/src/main/java/androidx/test/uiautomator/UiAutomatorHelpers.kt

@@ -46,3 +46,15 @@ enum class HasChildrenOp {
     EXACTLY,
     AT_MOST,
 }
+
+/**
+ * Waits until an object with [selector] if visible on screen and returns the object.
+ * If the element is not available in [timeout], throws [AssertionError]
+ */
+fun UiDevice.waitAndFindObject(selector: BySelector, timeout: Long): UiObject2 {
+    if (!wait(Until.hasObject(selector), timeout)) {
+        throw AssertionError("Element not found on screen in ${timeout}ms (selector=$selector)")
+    }
+
+    return findObject(selector)
+}

benchmarks/src/main/java/com/google/samples/apps/nowinandroid/foryou/ForYouActions.kt

@@ -20,6 +20,7 @@ import androidx.benchmark.macro.MacrobenchmarkScope
 import androidx.test.uiautomator.By
 import androidx.test.uiautomator.Until
 import androidx.test.uiautomator.untilHasChildren
+import androidx.test.uiautomator.waitAndFindObject
 import com.google.samples.apps.nowinandroid.flingElementDownUp
 
 fun MacrobenchmarkScope.forYouWaitForContent() {
@@ -27,7 +28,7 @@ fun MacrobenchmarkScope.forYouWaitForContent() {
     device.wait(Until.gone(By.res("loadingWheel")), 5_000)
     // Sometimes, the loading wheel is gone, but the content is not loaded yet
     // So we'll wait here for topics to be sure
-    val obj = device.findObject(By.res("forYou:topicSelection"))
+    val obj = device.waitAndFindObject(By.res("forYou:topicSelection"), 10_000)
     // Timeout here is quite big, because sometimes data loading takes a long time!
     obj.wait(untilHasChildren(), 60_000)
 }