test(preferences): de-flake PreferencesNavigationTest

AnkiDroid/src/androidTest/java/com/ichi2/anki/preferences/PreferencesNavigationTest.kt

@@ -38,6 +38,7 @@ import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.ichi2.anki.IntentHandler
 import com.ichi2.anki.R
 import com.ichi2.anki.testutil.GrantStoragePermission
+import com.ichi2.anki.testutil.awaitResumedActivity
 import com.ichi2.anki.testutil.closeGetStartedScreenIfExists
 import com.ichi2.anki.testutil.grantPermissions
 import com.ichi2.anki.utils.isWindowCompact
@@ -64,8 +65,7 @@ class PreferencesNavigationTest {
         assumeTrue(context.resources.isWindowCompact())
         ActivityScenario.launch(IntentHandler::class.java)
         closeGetStartedScreenIfExists()
-        onView(withId(R.id.drawer_layout)).perform(DrawerActions.open())
-        onView(withId(R.id.nav_settings)).perform(click())
+        openSettings()
         onView(withId(com.bytehamster.lib.preferencesearch.R.id.search)).perform(click())
         onView(allOf(withId(com.bytehamster.lib.preferencesearch.R.id.search), hasFocus())).perform(typeText("Controls"))
         // Checking the list of Settings Categories are displayed on the basis of our search "Controls"
@@ -91,8 +91,7 @@ class PreferencesNavigationTest {
         assumeTrue(isTablet(context))
         ActivityScenario.launch(IntentHandler::class.java)
         closeGetStartedScreenIfExists()
-        onView(withId(R.id.drawer_layout)).perform(DrawerActions.open())
-        onView(withId(R.id.nav_settings)).perform(click())
+        openSettings()
         onView(withId(com.bytehamster.lib.preferencesearch.R.id.search)).perform(click())
         onView(allOf(withId(com.bytehamster.lib.preferencesearch.R.id.search), hasFocus())).perform(typeText("Card"))
         onView(withText(R.string.card_zoom)).perform(click())
@@ -101,4 +100,11 @@ class PreferencesNavigationTest {
         pressBack()
         onView(withClassName(endsWith("PreferencesActivity"))).check(doesNotExist())
     }
+
+    /** Opens [PreferencesActivity] via the navigation drawer. */
+    private fun openSettings() {
+        onView(withId(R.id.drawer_layout)).perform(DrawerActions.open())
+        onView(withId(R.id.nav_settings)).perform(click())
+        awaitResumedActivity<PreferencesActivity>()
+    }
 }

AnkiDroid/src/androidTest/java/com/ichi2/anki/testutil/WaitUtils.kt

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package com.ichi2.anki.testutil
+
+import android.app.Activity
+import android.os.SystemClock
+import androidx.test.platform.app.InstrumentationRegistry
+import com.ichi2.anki.TestUtils
+import kotlin.test.fail
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.seconds
+
+/**
+ * Polls until [condition] returns true, syncing with the instrumentation between attempts.
+ * Fails the test with [message] if the condition does not hold within [timeout].
+ */
+fun waitUntil(
+    timeout: Duration = 10.seconds,
+    message: () -> String,
+    condition: () -> Boolean,
+) {
+    val instrumentation = InstrumentationRegistry.getInstrumentation()
+    val deadline = SystemClock.uptimeMillis() + timeout.inWholeMilliseconds
+    while (SystemClock.uptimeMillis() < deadline) {
+        if (condition()) return
+        instrumentation.waitForIdleSync()
+        SystemClock.sleep(50)
+    }
+    fail(message())
+}
+
+/**
+ * Polls until an activity of type [T] is resumed.
+ * Fails the test if [T] does not resume within [timeout].
+ */
+inline fun <reified T : Activity> awaitResumedActivity(timeout: Duration = 10.seconds) =
+    waitUntil(
+        timeout,
+        message = { "Timed out waiting for ${T::class.java.simpleName}; resumed = ${TestUtils.activityInstance}" },
+    ) { TestUtils.activityInstance is T }