Fix Wear navigation startDestination (android#1538)

Also add a unit test covering activity startup and navigation

Author: yschimke

Diff for: Jetcaster/wear/src/main/java/com/example/jetcaster/MainActivity.kt

@@ -20,16 +20,22 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
+import androidx.navigation.NavHostController
+import androidx.wear.compose.navigation.rememberSwipeDismissableNavController
 import dagger.hilt.android.AndroidEntryPoint
 
 @AndroidEntryPoint
 class MainActivity : ComponentActivity() {
+    lateinit var navController: NavHostController
+
     override fun onCreate(savedInstanceState: Bundle?) {
         installSplashScreen()
         super.onCreate(savedInstanceState)
 
         setContent {
-            WearApp()
+            navController = rememberSwipeDismissableNavController()
+
+            WearApp(navController)
         }
     }
 }

Diff for: Jetcaster/wear/src/main/java/com/example/jetcaster/WearApp.kt

@@ -25,9 +25,9 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.navigation.NavHostController
 import androidx.wear.compose.navigation.SwipeDismissableNavHost
 import androidx.wear.compose.navigation.composable
-import androidx.wear.compose.navigation.rememberSwipeDismissableNavController
 import androidx.wear.compose.navigation.rememberSwipeDismissableNavHostState
 import com.example.jetcaster.theme.WearAppTheme
 import com.example.jetcaster.ui.Episode
@@ -57,16 +57,14 @@ import com.google.android.horologist.media.ui.navigation.NavigationScreens
 import com.google.android.horologist.media.ui.screens.playerlibrarypager.PlayerLibraryPagerScreen
 
 @Composable
-fun WearApp() {
-
-    val navController = rememberSwipeDismissableNavController()
+fun WearApp(navController: NavHostController) {
     val navHostState = rememberSwipeDismissableNavHostState()
     val volumeViewModel: VolumeViewModel = viewModel(factory = VolumeViewModel.Factory)
 
     WearAppTheme {
         AppScaffold {
             SwipeDismissableNavHost(
-                startDestination = NavigationScreens.Player.navRoute,
+                startDestination = NavigationScreens.Player.playerDestination(),
                 navController = navController,
                 modifier = Modifier.background(Color.Transparent),
                 state = navHostState,

Diff for: Jetcaster/wear/src/test/java/com/example/jetcaster/NavigationTest.kt

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://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 com.example.jetcaster
+
+import androidx.compose.ui.test.junit4.createAndroidComposeRule
+import com.example.jetcaster.ui.JetcasterNavController.navigateToUpNext
+import org.junit.Assert.assertEquals
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+import org.robolectric.annotation.GraphicsMode
+
+@RunWith(RobolectricTestRunner::class)
+@Config(sdk = [34])
+@GraphicsMode(GraphicsMode.Mode.NATIVE)
+class NavigationTest {
+    @get:Rule
+    val rule = createAndroidComposeRule(MainActivity::class.java)
+
+    @Test
+    fun launchAndNavigate() {
+        val activity = rule.activity
+
+        val navController = activity.navController
+
+        rule.waitUntil {
+            navController.currentDestination?.route != null
+        }
+
+        assertEquals("player?page={page}", navController.currentDestination?.route)
+
+        navController.navigateToUpNext()
+
+        assertEquals("upNext", navController.currentDestination?.route)
+    }
+}