Adds topic screen

Bug: 213876743
Tests: Local + UI tests + Navigation test
Change-Id: I6c521695d6b777084a6255c6d62623a4def83063

app/build.gradle

@@ -118,6 +118,7 @@ android {
 dependencies {
     implementation project(':feature-following')
     implementation project(':feature-foryou')
+    implementation project(':feature-topic')
 
     implementation project(':core-ui')
 
@@ -126,6 +127,7 @@ dependencies {
     androidTestImplementation project(':core-testing')
     androidTestImplementation project(':core-datastore-test')
     androidTestImplementation project(':core-domain-test')
+    androidTestImplementation project(':core-network')
 
     coreLibraryDesugaring libs.android.desugarJdkLibs
 

app/src/androidTest/java/com/google/samples/apps/nowinandroid/ui/NavigationTest.kt

@@ -183,4 +183,21 @@ class NavigationTest {
             onNodeWithText(forYou).assertExists()
         }
     }
+
+    @Test
+    fun navigationBar_multipleBackStackFollowing() {
+        composeTestRule.apply {
+            onNodeWithText(topics).performClick()
+            onNodeWithText("Android Studio").performClick() // TODO: Grab string from fake data
+
+            // Switch tab
+            onNodeWithText(forYou).performClick()
+
+            // Come back to Following
+            onNodeWithText(topics).performClick()
+
+            // Verify we're not in the list of topics
+            onNodeWithText("Android Auto").assertDoesNotExist() // TODO: Grab string from fake data
+        }
+    }
 }

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -53,6 +53,8 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
+import androidx.navigation.NavDestination
+import androidx.navigation.NavDestination.Companion.hierarchy
 import androidx.navigation.compose.currentBackStackEntryAsState
 import androidx.navigation.compose.rememberNavController
 import com.google.samples.apps.nowinandroid.R
@@ -69,16 +71,17 @@ fun NiaApp(windowSizeClass: SizeClass) {
         }
 
         val navBackStackEntry by navController.currentBackStackEntryAsState()
-        val currentRoute =
+        val currentDestination = navBackStackEntry?.destination
-            navBackStackEntry?.destination?.route ?: NiaDestinations.FOR_YOU_ROUTE
 
         Scaffold(
             modifier = Modifier,
             bottomBar = {
-                if (windowSizeClass.width == WidthSizeClass.Compact) NiABottomBar(
+                if (windowSizeClass.width == WidthSizeClass.Compact) {
-                    navigationActions = navigationActions,
+                    NiABottomBar(
-                    currentRoute = currentRoute
+                        navigationActions = navigationActions,
-                )
+                        currentDestination = currentDestination
+                    )
+                }
             }
         ) { padding ->
             Surface(Modifier.fillMaxSize().statusBarsPadding()) {
@@ -86,7 +89,7 @@ fun NiaApp(windowSizeClass: SizeClass) {
                     if (windowSizeClass.width != WidthSizeClass.Compact) {
                         NiANavRail(
                             navigationActions = navigationActions,
-                            currentRoute = currentRoute
+                            currentDestination = currentDestination
                         )
                     }
                     NiaNavGraph(
@@ -102,11 +105,12 @@ fun NiaApp(windowSizeClass: SizeClass) {
 @Composable
 private fun NiANavRail(
     navigationActions: NiaNavigationActions,
-    currentRoute: String
+    currentDestination: NavDestination?
 ) {
     NavigationRail {
         TOP_LEVEL_DESTINATIONS.forEach { destination ->
-            val selected = currentRoute == destination.route
+            val selected =
+                currentDestination?.hierarchy?.any { it.route == destination.route } == true
             NavigationRailItem(
                 selected = selected,
                 onClick = { navigationActions.navigateToTopLevelDestination(destination.route) },
@@ -125,7 +129,7 @@ private fun NiANavRail(
 @Composable
 private fun NiABottomBar(
     navigationActions: NiaNavigationActions,
-    currentRoute: String
+    currentDestination: NavDestination?
 ) {
     // Wrap the navigation bar in a surface so the color behind the system
     // navigation is equal to the container color of the navigation bar.
@@ -137,20 +141,26 @@ private fun NiABottomBar(
                     .captionBarPadding(),
                 tonalElevation = 0.dp
             ) {
-                TOP_LEVEL_DESTINATIONS.forEach { dst ->
+
-                    val selected = currentRoute == dst.route
+                TOP_LEVEL_DESTINATIONS.forEach { destination ->
+                    val selected =
+                        currentDestination?.hierarchy?.any { it.route == destination.route } == true
                     NavigationBarItem(
                         selected = selected,
                         onClick = {
-                            navigationActions.navigateToTopLevelDestination(dst.route)
+                            navigationActions.navigateToTopLevelDestination(destination.route)
                         },
                         icon = {
                             Icon(
-                                if (selected) dst.selectedIcon else dst.unselectedIcon,
+                                if (selected) {
+                                    destination.selectedIcon
+                                } else {
+                                    destination.unselectedIcon
+                                },
                                 contentDescription = null
                             )
                         },
-                        label = { Text(stringResource(dst.iconTextId)) }
+                        label = { Text(stringResource(destination.iconTextId)) }
                     )
                 }
             }

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaNavGraph.kt

@@ -20,11 +20,18 @@ import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.navigation.NavHostController
+import androidx.navigation.NavType
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
+import androidx.navigation.compose.navigation
 import androidx.navigation.compose.rememberNavController
+import androidx.navigation.navArgument
 import com.google.samples.apps.nowinandroid.feature.following.FollowingRoute
 import com.google.samples.apps.nowinandroid.feature.foryou.ForYouRoute
+import com.google.samples.apps.nowinandroid.feature.topic.TopicDestinations
+import com.google.samples.apps.nowinandroid.feature.topic.TopicDestinationsArgs
+import com.google.samples.apps.nowinandroid.feature.topic.TopicRoute
+import com.google.samples.apps.nowinandroid.feature.topic.TopicScreens.TOPIC_SCREEN
 
 /**
  * Top-level navigation graph. Navigation is organized as explained at
@@ -52,17 +59,26 @@ fun NiaNavGraph(
         composable(NiaDestinations.SAVED_ROUTE) {
             Text("SAVED", modifier)
         }
-        composable(NiaDestinations.FOLLOWING_ROUTE) {
+        navigation(
-            FollowingRoute(
+            startDestination = TopicDestinations.TOPICS_ROUTE,
-                navigateToTopic = { navController.navigate(NiaDestinations.TOPIC_ROUTE) },
+            route = NiaDestinations.FOLLOWING_ROUTE
-                modifier = modifier
+        ) {
-            )
+            composable(TopicDestinations.TOPICS_ROUTE) {
-        }
+                FollowingRoute(
-        composable(NiaDestinations.TOPIC_ROUTE) {
+                    navigateToTopic = { navController.navigate("$TOPIC_SCREEN/$it") },
-            Text(
+                    modifier = modifier
-                text = "Topic",
+                )
-                modifier = modifier
+            }
-            )
+            composable(
+                TopicDestinations.TOPIC_ROUTE,
+                arguments = listOf(
+                    navArgument(TopicDestinationsArgs.TOPIC_ID_ARG) {
+                        type = NavType.IntType
+                    }
+                )
+            ) {
+                TopicRoute(onBackClick = { navController.popBackStack() })
+            }
         }
     }
 }

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaNavigation.kt

@@ -29,7 +29,6 @@ object NiaDestinations {
     const val EPISODES_ROUTE = "episodes"
     const val SAVED_ROUTE = "saved"
     const val FOLLOWING_ROUTE = "following"
-    const val TOPIC_ROUTE = "topic"
 }
 
 /**

core-common/src/main/java/com/google/samples/apps/nowinandroid/core/result/Result.kt

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2022 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.google.samples.apps.nowinandroid.core.result
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onStart
+
+sealed interface Result<out T> {
+    data class Success<T>(val data: T) : Result<T>
+    data class Error(val exception: Throwable? = null) : Result<Nothing>
+    object Loading : Result<Nothing>
+}
+
+fun <T> Flow<T>.asResult(): Flow<Result<T>> {
+    return this
+        .map<T, Result<T>> {
+            Result.Success(it)
+        }
+        .onStart { emit(Result.Loading) }
+}

core-database/src/main/java/com/google/samples/apps/nowinandroid/core/database/dao/TopicDao.kt

@@ -30,6 +30,14 @@ import kotlinx.coroutines.flow.Flow
  */
 @Dao
 interface TopicDao {
+    @Query(
+        value = """
+        SELECT * FROM topics
+        WHERE id = :topicId
+    """
+    )
+    fun getTopicEntity(topicId: Int): Flow<TopicEntity>
+
     @Query(value = "SELECT * FROM topics")
     fun getTopicEntitiesStream(): Flow<List<TopicEntity>>
 

core-domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/repository/LocalTopicsRepository.kt

@@ -42,6 +42,9 @@ class LocalTopicsRepository @Inject constructor(
         topicDao.getTopicEntitiesStream()
             .map { it.map(TopicEntity::asExternalModel) }
 
+    override fun getTopic(id: Int): Flow<Topic> =
+        topicDao.getTopicEntity(id).map { it.asExternalModel() }
+
     override suspend fun setFollowedTopicIds(followedTopicIds: Set<Int>) =
         niaPreferences.setFollowedTopicIds(followedTopicIds)
 

core-domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/repository/TopicsRepository.kt

@@ -25,6 +25,11 @@ interface TopicsRepository {
      */
     fun getTopicsStream(): Flow<List<Topic>>
 
+    /**
+     * Gets data for a specific topic
+     */
+    fun getTopic(id: Int): Flow<Topic>
+
     /**
      * Sets the user's currently followed topics
      */

core-domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/repository/fake/FakeTopicsRepository.kt

@@ -28,6 +28,7 @@ import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.map
 import kotlinx.serialization.decodeFromString
 import kotlinx.serialization.json.Json
 
@@ -59,6 +60,10 @@ class FakeTopicsRepository @Inject constructor(
     }
         .flowOn(ioDispatcher)
 
+    override fun getTopic(id: Int): Flow<Topic> {
+        return getTopicsStream().map { it.first { topic -> topic.id == id } }
+    }
+
     override suspend fun setFollowedTopicIds(followedTopicIds: Set<Int>) =
         niaPreferences.setFollowedTopicIds(followedTopicIds)
 

core-domain/src/test/java/com/google/samples/apps/nowinandroid/core/domain/repository/LocalTopicsRepositoryTest.kt

@@ -58,7 +58,7 @@ class LocalTopicsRepositoryTest {
         subject = LocalTopicsRepository(
             topicDao = topicDao,
             network = network,
-            niaPreferences = niaPreferences,
+            niaPreferences = niaPreferences
         )
     }
 

core-domain/src/test/java/com/google/samples/apps/nowinandroid/core/domain/testdoubles/TestTopicDao.kt

@@ -40,6 +40,10 @@ class TestTopicDao : TopicDao {
         )
     )
 
+    override fun getTopicEntity(topicId: Int): Flow<TopicEntity> {
+        throw NotImplementedError("Unused in tests")
+    }
+
     override fun getTopicEntitiesStream(): Flow<List<TopicEntity>> =
         entitiesStateFlow
 

core-testing/build.gradle

@@ -63,4 +63,4 @@ dependencies {
             force 'org.objenesis:objenesis:2.6'
         }
     }
-}
+}

core-testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/repository/TestTopicsRepository.kt

@@ -21,6 +21,7 @@ import com.google.samples.apps.nowinandroid.core.model.data.Topic
 import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.map
 
 class TestTopicsRepository : TopicsRepository {
     /**
@@ -37,6 +38,10 @@ class TestTopicsRepository : TopicsRepository {
 
     override fun getTopicsStream(): Flow<List<Topic>> = topicsFlow
 
+    override fun getTopic(id: Int): Flow<Topic> {
+        return topicsFlow.map { topics -> topics.find { it.id == id }!! }
+    }
+
     override suspend fun setFollowedTopicIds(followedTopicIds: Set<Int>) {
         _followedTopicIds.tryEmit(followedTopicIds)
     }

core-ui/src/main/res/values/strings.xml

@@ -16,6 +16,7 @@
 <resources>
     <string name="bookmark">Bookmark</string>
     <string name="unbookmark">Unbookmark</string>
+    <string name="back">Back</string>
 
     <string name="card_tap_action">Open Resource Link</string>
 </resources>

feature-following/build.gradle

@@ -71,4 +71,4 @@ dependencies {
             force 'org.objenesis:objenesis:2.6'
         }
     }
-}
+}

feature-following/src/main/java/com/google/samples/apps/nowinandroid/feature/following/FollowingScreen.kt

@@ -55,7 +55,7 @@ import com.google.samples.apps.nowinandroid.core.ui.theme.NiaTheme
 @Composable
 fun FollowingRoute(
     modifier: Modifier = Modifier,
-    navigateToTopic: () -> Unit,
+    navigateToTopic: (Int) -> Unit,
     viewModel: FollowingViewModel = hiltViewModel()
 ) {
     val uiState by viewModel.uiState.collectAsState()
@@ -72,7 +72,7 @@ fun FollowingRoute(
 fun FollowingScreen(
     uiState: FollowingUiState,
     followTopic: (Int, Boolean) -> Unit,
-    navigateToTopic: () -> Unit,
+    navigateToTopic: (Int) -> Unit,
     modifier: Modifier = Modifier,
 ) {
     Column(
@@ -89,7 +89,7 @@ fun FollowingScreen(
             is FollowingUiState.Topics ->
                 FollowingWithTopicsScreen(
                     uiState = uiState,
-                    onTopicClick = { navigateToTopic() },
+                    onTopicClick = navigateToTopic,
                     onFollowButtonClick = followTopic,
                 )
             is FollowingUiState.Error -> FollowingErrorScreen()
@@ -101,7 +101,7 @@ fun FollowingScreen(
 fun FollowingWithTopicsScreen(
     modifier: Modifier = Modifier,
     uiState: FollowingUiState.Topics,
-    onTopicClick: () -> Unit,
+    onTopicClick: (Int) -> Unit,
     onFollowButtonClick: (Int, Boolean) -> Unit
 ) {
     LazyColumn(
@@ -111,7 +111,7 @@ fun FollowingWithTopicsScreen(
             item {
                 FollowingTopicCard(
                     followableTopic = followableTopic,
-                    onTopicClick = onTopicClick,
+                    onTopicClick = { onTopicClick(followableTopic.topic.id) },
                     onFollowButtonClick = onFollowButtonClick
                 )
             }

feature-following/src/test/java/com/google/samples/apps/nowinandroid/following/FollowingViewModelTest.kt

@@ -61,21 +61,29 @@ class FollowingViewModelTest {
 
     @Test
     fun uiState_whenFollowingNewTopic_thenShowUpdatedTopics() = runTest {
+
+        val toggleTopicId = testOutputTopics[1].topic.id
         viewModel.uiState
             .test {
                 awaitItem()
                 topicsRepository.sendTopics(testInputTopics.map { it.topic })
                 topicsRepository.setFollowedTopicIds(setOf(testInputTopics[0].topic.id))
 
-                awaitItem()
+                assertEquals(
+                    false,
+                    (awaitItem() as FollowingUiState.Topics)
+                        .topics.first { it.topic.id == toggleTopicId }.isFollowed
+                )
+
                 viewModel.followTopic(
-                    followedTopicId = testInputTopics[1].topic.id,
+                    followedTopicId = toggleTopicId,
-                    followed = true
+                    true
                 )
 
                 assertEquals(
-                    FollowingUiState.Topics(topics = testOutputTopics),
+                    true,
-                    awaitItem()
+                    (awaitItem() as FollowingUiState.Topics)
+                        .topics.first { it.topic.id == toggleTopicId }.isFollowed
                 )
                 cancel()
             }
@@ -83,6 +91,7 @@ class FollowingViewModelTest {
 
     @Test
     fun uiState_whenUnfollowingTopics_thenShowUpdatedTopics() = runTest {
+        val toggleTopicId = testOutputTopics[1].topic.id
         viewModel.uiState
             .test {
                 awaitItem()
@@ -91,17 +100,21 @@ class FollowingViewModelTest {
                     setOf(testOutputTopics[0].topic.id, testOutputTopics[1].topic.id)
                 )
 
-                awaitItem()
+                assertEquals(
+                    true,
+                    (awaitItem() as FollowingUiState.Topics)
+                        .topics.first { it.topic.id == toggleTopicId }.isFollowed
+                )
+
                 viewModel.followTopic(
-                    followedTopicId = testOutputTopics[1].topic.id,
+                    followedTopicId = toggleTopicId,
-                    followed = false
+                    false
                 )
 
                 assertEquals(
-                    FollowingUiState.Topics(
+                    false,
-                        topics = testInputTopics
+                    (awaitItem() as FollowingUiState.Topics)
-                    ),
+                        .topics.first { it.topic.id == toggleTopicId }.isFollowed
-                    awaitItem()
                 )
                 cancel()
             }

feature-topic/.gitignore

@@ -0,0 +1 @@
+/build

feature-topic/build.gradle

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2022 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.
+ */
+plugins {
+    id 'com.android.library'
+    id 'kotlin-android'
+    id 'kotlin-kapt'
+    id 'dagger.hilt.android.plugin'
+}
+
+android {
+    compileSdk buildConfig.compileSdk
+
+    defaultConfig {
+        minSdk buildConfig.minSdk
+        targetSdk buildConfig.targetSdk
+
+        testInstrumentationRunner "com.google.samples.apps.nowinandroid.core.testing.NiaTestRunner"
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+    buildFeatures {
+        compose true
+    }
+    composeOptions {
+        kotlinCompilerExtensionVersion libs.versions.androidxCompose.get()
+    }
+}
+
+dependencies {
+    implementation project(':core-model')
+    implementation project(':core-ui')
+    implementation project(':core-domain')
+    implementation project(':core-common')
+
+    testImplementation project(':core-testing')
+    androidTestImplementation project(':core-testing')
+
+    implementation libs.kotlinx.coroutines.android
+    implementation libs.kotlinx.datetime
+
+    implementation libs.androidx.hilt.navigation.compose
+    implementation libs.androidx.lifecycle.viewModelCompose
+
+    implementation libs.hilt.android
+    kapt libs.hilt.compiler
+
+    // androidx.test is forcing JUnit, 4.12. This forces it to use 4.13
+    configurations.configureEach {
+        resolutionStrategy {
+            force libs.junit4
+            // Temporary workaround for https://issuetracker.google.com/174733673
+            force 'org.objenesis:objenesis:2.6'
+        }
+    }
+}

feature-topic/src/androidTest/java/com/google/samples/apps/nowinandroid/following/TopicScreenTest.kt

@@ -0,0 +1,195 @@
+/*
+ * Copyright 2022 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.google.samples.apps.nowinandroid.following
+
+import androidx.activity.ComponentActivity
+import androidx.compose.ui.test.junit4.createAndroidComposeRule
+import androidx.compose.ui.test.onNodeWithContentDescription
+import androidx.compose.ui.test.onNodeWithText
+import com.google.samples.apps.nowinandroid.core.model.data.FollowableTopic
+import com.google.samples.apps.nowinandroid.core.model.data.NewsResource
+import com.google.samples.apps.nowinandroid.core.model.data.NewsResourceType.Video
+import com.google.samples.apps.nowinandroid.core.model.data.Topic
+import com.google.samples.apps.nowinandroid.feature.topic.NewsUiState
+import com.google.samples.apps.nowinandroid.feature.topic.R
+import com.google.samples.apps.nowinandroid.feature.topic.TopicScreen
+import com.google.samples.apps.nowinandroid.feature.topic.TopicScreenUiState
+import com.google.samples.apps.nowinandroid.feature.topic.TopicUiState
+import kotlinx.datetime.Instant
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+
+/**
+ * UI test for checking the correct behaviour of the Topic screen;
+ * Verifies that, when a specific UiState is set, the corresponding
+ * composables and details are shown
+ */
+class TopicScreenTest {
+
+    @get:Rule
+    val composeTestRule = createAndroidComposeRule<ComponentActivity>()
+
+    private lateinit var topicLoading: String
+
+    @Before
+    fun setup() {
+        composeTestRule.activity.apply {
+            topicLoading = getString(R.string.topic_loading)
+        }
+    }
+
+    @Test
+    fun niaLoadingIndicator_whenScreenIsLoading_showLoading() {
+        composeTestRule.setContent {
+            TopicScreen(
+                uiState = TopicScreenUiState(
+                    topicState = TopicUiState.Loading,
+                    newsState = NewsUiState.Loading
+                ),
+                onBackClick = { },
+                onFollowClick = { }
+            )
+        }
+
+        composeTestRule
+            .onNodeWithContentDescription(topicLoading)
+            .assertExists()
+    }
+
+    @Test
+    fun topicTitle_whenTopicIsSuccess_isShown() {
+        val testTopic = testTopics.first()
+        composeTestRule.setContent {
+            TopicScreen(
+                uiState = TopicScreenUiState(
+                    topicState = TopicUiState.Success(testTopic),
+                    newsState = NewsUiState.Loading
+                ),
+                onBackClick = { },
+                onFollowClick = { }
+            )
+        }
+
+        // Name is shown
+        composeTestRule
+            .onNodeWithText(testTopic.topic.name)
+            .assertExists()
+
+        // Description is shown
+        composeTestRule
+            .onNodeWithText(testTopic.topic.description)
+            .assertExists()
+    }
+
+    @Test
+    fun news_whenTopicIsLoading_isNotShown() {
+        val testTopic = testTopics.first()
+        composeTestRule.setContent {
+            TopicScreen(
+                uiState = TopicScreenUiState(
+                    topicState = TopicUiState.Loading,
+                    newsState = NewsUiState.Success(sampleNewsResources)
+                ),
+                onBackClick = { },
+                onFollowClick = { }
+            )
+        }
+
+        // Loading indicator shown
+        composeTestRule
+            .onNodeWithContentDescription(topicLoading)
+            .assertExists()
+    }
+    @Test
+    fun news_whenSuccessAndTopicIsSuccess_isShown() {
+        val testTopic = testTopics.first()
+        composeTestRule.setContent {
+            TopicScreen(
+                uiState = TopicScreenUiState(
+                    topicState = TopicUiState.Success(testTopic),
+                    newsState = NewsUiState.Success(sampleNewsResources)
+                ),
+                onBackClick = { },
+                onFollowClick = { }
+            )
+        }
+
+        // First news title shown
+        composeTestRule
+            .onNodeWithText(sampleNewsResources.first().title)
+            .assertExists()
+    }
+}
+
+private const val TOPIC_1_NAME = "Headlines"
+private const val TOPIC_2_NAME = "UI"
+private const val TOPIC_3_NAME = "Tools"
+private const val TOPIC_DESC = "At vero eos et accusamus et iusto odio dignissimos ducimus qui."
+
+private val testTopics = listOf(
+    FollowableTopic(
+        Topic(
+            id = 0,
+            name = TOPIC_1_NAME,
+            description = TOPIC_DESC,
+        ),
+        isFollowed = true
+    ),
+    FollowableTopic(
+        Topic(
+            id = 1,
+            name = TOPIC_2_NAME,
+            description = TOPIC_DESC
+        ),
+        isFollowed = false
+    ),
+    FollowableTopic(
+        Topic(
+            id = 2,
+            name = TOPIC_3_NAME,
+            description = TOPIC_DESC
+        ),
+        isFollowed = false
+    )
+)
+
+private val numberOfUnfollowedTopics = testTopics.filter { !it.isFollowed }.size
+
+private val sampleNewsResources = listOf(
+    NewsResource(
+        id = 1,
+        episodeId = 52,
+        title = "Thanks for helping us reach 1M YouTube Subscribers",
+        content = "Thank you everyone for following the Now in Android series and everything the " +
+            "Android Developers YouTube channel has to offer. During the Android Developer " +
+            "Summit, our YouTube channel reached 1 million subscribers! Here’s a small video to " +
+            "thank you all.",
+        url = "https://youtu.be/-fJ6poHQrjM",
+        headerImageUrl = "https://i.ytimg.com/vi/-fJ6poHQrjM/maxresdefault.jpg",
+        publishDate = Instant.parse("2021-11-09T00:00:00.000Z"),
+        type = Video,
+        topics = listOf(
+            Topic(
+                id = 0,
+                name = "Headlines",
+                description = ""
+            )
+        ),
+        authors = emptyList()
+    )
+)

feature-topic/src/main/AndroidManifest.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.google.samples.apps.nowinandroid.feature.topic">
+
+</manifest>

feature-topic/src/main/java/com/google/samples/apps/nowinandroid/feature/topic/Navigation.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2022 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.google.samples.apps.nowinandroid.feature.topic
+
+import com.google.samples.apps.nowinandroid.feature.topic.TopicDestinationsArgs.TOPIC_ID_ARG
+import com.google.samples.apps.nowinandroid.feature.topic.TopicScreens.TOPIC_SCREEN
+
+object TopicDestinations {
+    const val TOPICS_ROUTE = "topics"
+    const val TOPIC_ROUTE = "$TOPIC_SCREEN/{$TOPIC_ID_ARG}"
+}
+
+object TopicDestinationsArgs {
+    const val TOPIC_ID_ARG = "topicId"
+}
+
+object TopicScreens {
+    const val TOPIC_SCREEN = "topic"
+}

feature-topic/src/main/java/com/google/samples/apps/nowinandroid/feature/topic/TopicScreen.kt

@@ -0,0 +1,193 @@
+/*
+ * Copyright 2021 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.google.samples.apps.nowinandroid.feature.topic
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.material.Chip
+import androidx.compose.material.ExperimentalMaterialApi
+import androidx.compose.material.Icon
+import androidx.compose.material.icons.Icons.Filled
+import androidx.compose.material.icons.filled.ArrowBack
+import androidx.compose.material.icons.filled.Check
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Brush
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import com.google.samples.apps.nowinandroid.core.model.data.FollowableTopic
+import com.google.samples.apps.nowinandroid.core.ui.NiaLoadingIndicator
+import com.google.samples.apps.nowinandroid.feature.topic.R.string
+import com.google.samples.apps.nowinandroid.feature.topic.TopicUiState.Loading
+
+@Composable
+fun TopicRoute(
+    onBackClick: () -> Unit,
+    modifier: Modifier = Modifier,
+    viewModel: TopicViewModel = hiltViewModel(),
+) {
+    val uiState: TopicScreenUiState by viewModel.uiState.collectAsState()
+
+    TopicScreen(
+        topicState = uiState.topicState,
+        newsState = uiState.newsState,
+        modifier = modifier,
+        onBackClick = onBackClick,
+        onFollowClick = viewModel::followTopicToggle,
+    )
+}
+
+@Composable
+private fun TopicScreen(
+    topicState: TopicUiState,
+    newsState: NewsUiState,
+    onBackClick: () -> Unit,
+    onFollowClick: (Boolean) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    Column(
+        modifier = modifier,
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+        when (topicState) {
+            Loading ->
+                NiaLoadingIndicator(
+                    modifier = modifier,
+                    contentDesc = stringResource(id = string.topic_loading),
+                )
+            TopicUiState.Error -> TODO()
+            is TopicUiState.Success -> {
+                TopicToolbar(
+                    onBackClick = onBackClick,
+                    onFollowClick = onFollowClick,
+                    uiState = topicState.followableTopic
+                )
+                TopicBody(
+                    name = topicState.followableTopic.topic.name,
+                    description = topicState.followableTopic.topic.longDescription,
+                    news = newsState
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun TopicBody(name: String, description: String, news: NewsUiState) {
+    Column(modifier = Modifier.padding(horizontal = 24.dp)) {
+        // TODO: Show icon if available
+        Box(
+            modifier = Modifier
+                .size(216.dp)
+                .align(Alignment.CenterHorizontally)
+                .background(
+                    brush = Brush.radialGradient(
+                        colors = listOf(Color.Black, Color.White)
+                    )
+                )
+                .padding(bottom = 12.dp)
+        )
+        Text(name, style = MaterialTheme.typography.displayMedium)
+        if (description.isNotEmpty()) {
+            Text(
+                description,
+                modifier = Modifier.padding(top = 24.dp),
+                style = MaterialTheme.typography.bodyLarge
+            )
+        }
+        TopicList(news, Modifier.padding(top = 24.dp))
+    }
+}
+
+@Composable
+private fun TopicList(news: NewsUiState, modifier: Modifier = Modifier) {
+    when (news) {
+        is NewsUiState.Success -> {
+            LazyColumn(modifier = modifier) {
+                items(news.news.size) { index ->
+                    Text(news.news[index].title)
+                }
+            }
+        }
+        is NewsUiState.Loading -> {
+            NiaLoadingIndicator(contentDesc = "Loading news") // TODO
+        }
+        else -> {
+            Text("Error") // TODO
+        }
+    }
+}
+
+@Preview
+@Composable
+private fun TopicBodyPreview() {
+    MaterialTheme {
+        TopicBody("Jetpack Compose", "Lorem ipsum maximum", NewsUiState.Success(emptyList()))
+    }
+}
+
+@OptIn(ExperimentalMaterialApi::class)
+@Composable
+private fun TopicToolbar(
+    uiState: FollowableTopic,
+    modifier: Modifier = Modifier,
+    onBackClick: () -> Unit = {},
+    onFollowClick: (Boolean) -> Unit = {},
+) {
+    Row(
+        horizontalArrangement = Arrangement.SpaceBetween,
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = modifier
+            .fillMaxWidth()
+            .padding(bottom = 32.dp)
+    ) {
+        IconButton(onClick = { onBackClick() }) {
+            Icon(
+                imageVector = Filled.ArrowBack,
+                contentDescription = stringResource(id = R.string.back)
+            )
+        }
+        val selected = uiState.isFollowed
+        Chip(onClick = { onFollowClick(!selected) }) {
+            if (selected) {
+                Icon(
+                    imageVector = Filled.Check,
+                    contentDescription = null
+                )
+                Text("FOLLOWING")
+            } else {
+                Text("NOT FOLLOWING")
+            }
+        }
+    }
+}

feature-topic/src/main/java/com/google/samples/apps/nowinandroid/feature/topic/TopicViewModel.kt

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2021 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.google.samples.apps.nowinandroid.feature.topic
+
+import androidx.lifecycle.SavedStateHandle
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.google.samples.apps.nowinandroid.core.domain.repository.NewsRepository
+import com.google.samples.apps.nowinandroid.core.domain.repository.TopicsRepository
+import com.google.samples.apps.nowinandroid.core.model.data.FollowableTopic
+import com.google.samples.apps.nowinandroid.core.model.data.NewsResource
+import com.google.samples.apps.nowinandroid.core.model.data.Topic
+import com.google.samples.apps.nowinandroid.core.result.Result
+import com.google.samples.apps.nowinandroid.core.result.asResult
+import dagger.hilt.android.lifecycle.HiltViewModel
+import javax.inject.Inject
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
+
+@HiltViewModel
+class TopicViewModel @Inject constructor(
+    savedStateHandle: SavedStateHandle,
+    private val topicsRepository: TopicsRepository,
+    newsRepository: NewsRepository
+) : ViewModel() {
+
+    private val topicId: Int = checkNotNull(savedStateHandle[TopicDestinationsArgs.TOPIC_ID_ARG])
+
+    // Observe the followed topics, as they could change over time.
+    private val followedTopicIdsStream: Flow<Result<Set<Int>>> =
+        topicsRepository.getFollowedTopicIdsStream().asResult()
+
+    // Observe topic information
+    private val topic: Flow<Result<Topic>> = topicsRepository.getTopic(topicId).asResult()
+
+    // Observe the News for this topic
+    private val newsStream: Flow<Result<List<NewsResource>>> =
+        newsRepository.getNewsResourcesStream(setOf(topicId)).asResult()
+
+    val uiState: StateFlow<TopicScreenUiState> =
+        combine(
+            followedTopicIdsStream,
+            topic,
+            newsStream
+        ) { followedTopicsResult, topicResult, newsResult ->
+            val topic: TopicUiState =
+                if (topicResult is Result.Success && followedTopicsResult is Result.Success) {
+                    val followed = followedTopicsResult.data.contains(topicId)
+                    TopicUiState.Success(
+                        followableTopic = FollowableTopic(
+                            topic = topicResult.data,
+                            isFollowed = followed
+                        )
+                    )
+                } else if (
+                    topicResult is Result.Loading || followedTopicsResult is Result.Loading
+                ) {
+                    TopicUiState.Loading
+                } else {
+                    TopicUiState.Error
+                }
+
+            val news: NewsUiState = when (newsResult) {
+                is Result.Success -> NewsUiState.Success(newsResult.data)
+                is Result.Loading -> NewsUiState.Loading
+                is Result.Error -> NewsUiState.Error
+            }
+
+            TopicScreenUiState(topic, news)
+        }
+            .stateIn(
+                scope = viewModelScope,
+                started = SharingStarted.WhileSubscribed(5_000),
+                initialValue = TopicScreenUiState(TopicUiState.Loading, NewsUiState.Loading)
+            )
+
+    fun followTopicToggle(followed: Boolean) {
+        viewModelScope.launch {
+            topicsRepository.toggleFollowedTopicId(topicId, followed)
+        }
+    }
+}
+
+sealed interface TopicUiState {
+    data class Success(val followableTopic: FollowableTopic) : TopicUiState
+    object Error : TopicUiState
+    object Loading : TopicUiState
+}
+
+sealed interface NewsUiState {
+    data class Success(val news: List<NewsResource>) : NewsUiState
+    object Error : NewsUiState
+    object Loading : NewsUiState
+}
+
+data class TopicScreenUiState(
+    val topicState: TopicUiState,
+    val newsState: NewsUiState
+)

feature-topic/src/main/res/values/strings.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2022 Google LLC
+  ~
+  ~ 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.
+-->
+<resources>
+    <string name="topic">Topic</string>
+    <string name="topic_loading">Loading topic</string>
+</resources>

feature-topic/src/test/java/com/google/samples/apps/nowinandroid/following/TopicViewModelTest.kt

@@ -0,0 +1,237 @@
+/*
+ * Copyright 2022 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.google.samples.apps.nowinandroid.following
+
+import androidx.lifecycle.SavedStateHandle
+import app.cash.turbine.test
+import com.google.samples.apps.nowinandroid.core.model.data.FollowableTopic
+import com.google.samples.apps.nowinandroid.core.model.data.NewsResource
+import com.google.samples.apps.nowinandroid.core.model.data.NewsResourceType.Video
+import com.google.samples.apps.nowinandroid.core.model.data.Topic
+import com.google.samples.apps.nowinandroid.core.testing.repository.TestNewsRepository
+import com.google.samples.apps.nowinandroid.core.testing.repository.TestTopicsRepository
+import com.google.samples.apps.nowinandroid.core.testing.util.TestDispatcherRule
+import com.google.samples.apps.nowinandroid.feature.topic.NewsUiState
+import com.google.samples.apps.nowinandroid.feature.topic.TopicDestinationsArgs.TOPIC_ID_ARG
+import com.google.samples.apps.nowinandroid.feature.topic.TopicUiState
+import com.google.samples.apps.nowinandroid.feature.topic.TopicViewModel
+import kotlinx.coroutines.test.runTest
+import kotlinx.datetime.Instant
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+
+class TopicViewModelTest {
+
+    @get:Rule
+    val dispatcherRule = TestDispatcherRule()
+
+    private val topicsRepository = TestTopicsRepository()
+    private val newsRepository = TestNewsRepository()
+    private lateinit var viewModel: TopicViewModel
+
+    @Before
+    fun setup() {
+        viewModel = TopicViewModel(
+            savedStateHandle = SavedStateHandle(mapOf(TOPIC_ID_ARG to testInputTopics[0].topic.id)),
+            topicsRepository = topicsRepository,
+            newsRepository = newsRepository
+        )
+    }
+
+    @Test
+    fun uiStateNews_whenInitialized_thenShowLoading() = runTest {
+        viewModel.uiState.test {
+            assertEquals(NewsUiState.Loading, awaitItem().newsState)
+            cancel()
+        }
+    }
+
+    @Test
+    fun uiStateTopic_whenInitialized_thenShowLoading() = runTest {
+        viewModel.uiState.test {
+            assertEquals(TopicUiState.Loading, awaitItem().topicState)
+            cancel()
+        }
+    }
+
+    @Test
+    fun uiStateTopic_whenFollowedIdsSuccessAndTopicLoading_thenShowLoading() = runTest {
+        viewModel.uiState.test {
+            topicsRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
+            assertEquals(TopicUiState.Loading, awaitItem().topicState)
+            cancel()
+        }
+    }
+
+    @Test
+    fun uiStateTopic_whenFollowedIdsSuccessAndTopicSuccess_thenTopicSuccessAndNewsLoading() =
+        runTest {
+            viewModel.uiState.test {
+                awaitItem()
+                topicsRepository.sendTopics(testInputTopics.map { it.topic })
+                topicsRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
+                val item = awaitItem()
+                assertTrue(item.topicState is TopicUiState.Success)
+                assertTrue(item.newsState is NewsUiState.Loading)
+                cancel()
+            }
+        }
+
+    @Test
+    fun uiStateTopic_whenFollowedIdsSuccessAndTopicSuccessAndNewsIsSuccess_thenAllSuccess() =
+        runTest {
+            viewModel.uiState.test {
+                awaitItem()
+                topicsRepository.sendTopics(testInputTopics.map { it.topic })
+                topicsRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
+                newsRepository.sendNewsResources(sampleNewsResources)
+                val item = awaitItem()
+                assertTrue(item.topicState is TopicUiState.Success)
+                assertTrue(item.newsState is NewsUiState.Success)
+                cancel()
+            }
+        }
+
+    @Test
+    fun uiStateTopic_whenFollowingTopic_thenShowUpdatedTopic() = runTest {
+        viewModel.uiState
+            .test {
+                awaitItem()
+                topicsRepository.sendTopics(testInputTopics.map { it.topic })
+                // Set which topic IDs are followed, not including 0.
+                topicsRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
+
+                viewModel.followTopicToggle(true)
+
+                assertEquals(
+                    TopicUiState.Success(followableTopic = testOutputTopics[0]),
+                    awaitItem().topicState
+                )
+                cancel()
+            }
+    }
+}
+
+private const val TOPIC_1_NAME = "Android Studio"
+private const val TOPIC_2_NAME = "Build"
+private const val TOPIC_3_NAME = "Compose"
+private const val TOPIC_SHORT_DESC = "At vero eos et accusamus."
+private const val TOPIC_LONG_DESC = "At vero eos et accusamus et iusto odio dignissimos ducimus."
+private const val TOPIC_URL = "URL"
+private const val TOPIC_IMAGE_URL = "Image URL"
+
+private val testInputTopics = listOf(
+    FollowableTopic(
+        Topic(
+            id = 0,
+            name = TOPIC_1_NAME,
+            shortDescription = TOPIC_SHORT_DESC,
+            longDescription = TOPIC_LONG_DESC,
+            url = TOPIC_URL,
+            imageUrl = TOPIC_IMAGE_URL,
+        ),
+        isFollowed = true
+    ),
+    FollowableTopic(
+        Topic(
+            id = 1,
+            name = TOPIC_2_NAME,
+            shortDescription = TOPIC_SHORT_DESC,
+            longDescription = TOPIC_LONG_DESC,
+            url = TOPIC_URL,
+            imageUrl = TOPIC_IMAGE_URL,
+        ),
+        isFollowed = false
+    ),
+    FollowableTopic(
+        Topic(
+            id = 2,
+            name = TOPIC_3_NAME,
+            shortDescription = TOPIC_SHORT_DESC,
+            longDescription = TOPIC_LONG_DESC,
+            url = TOPIC_URL,
+            imageUrl = TOPIC_IMAGE_URL,
+        ),
+        isFollowed = false
+    )
+)
+
+private val testOutputTopics = listOf(
+    FollowableTopic(
+        Topic(
+            id = 0,
+            name = TOPIC_1_NAME,
+            shortDescription = TOPIC_SHORT_DESC,
+            longDescription = TOPIC_LONG_DESC,
+            url = TOPIC_URL,
+            imageUrl = TOPIC_IMAGE_URL,
+        ),
+        isFollowed = true
+    ),
+    FollowableTopic(
+        Topic(
+            id = 1,
+            name = TOPIC_2_NAME,
+            shortDescription = TOPIC_SHORT_DESC,
+            longDescription = TOPIC_LONG_DESC,
+            url = TOPIC_URL,
+            imageUrl = TOPIC_IMAGE_URL,
+        ),
+        isFollowed = true
+    ),
+    FollowableTopic(
+        Topic(
+            id = 2,
+            name = TOPIC_3_NAME,
+            shortDescription = TOPIC_SHORT_DESC,
+            longDescription = TOPIC_LONG_DESC,
+            url = TOPIC_URL,
+            imageUrl = TOPIC_IMAGE_URL,
+        ),
+        isFollowed = false
+    )
+)
+
+private val sampleNewsResources = listOf(
+    NewsResource(
+        id = 1,
+        episodeId = 52,
+        title = "Thanks for helping us reach 1M YouTube Subscribers",
+        content = "Thank you everyone for following the Now in Android series and everything the " +
+            "Android Developers YouTube channel has to offer. During the Android Developer " +
+            "Summit, our YouTube channel reached 1 million subscribers! Here’s a small video to " +
+            "thank you all.",
+        url = "https://youtu.be/-fJ6poHQrjM",
+        headerImageUrl = "https://i.ytimg.com/vi/-fJ6poHQrjM/maxresdefault.jpg",
+        publishDate = Instant.parse("2021-11-09T00:00:00.000Z"),
+        type = Video,
+        topics = listOf(
+            Topic(
+                id = 0,
+                name = "Headlines",
+                shortDescription = "",
+                longDescription = "long description",
+                url = "URL",
+                imageUrl = "image URL",
+            )
+        ),
+        authors = emptyList()
+    )
+)

settings.gradle

@@ -46,4 +46,5 @@ include ':core-ui'
 include ':core-testing'
 include ':feature-following'
 include ':feature-foryou'
+include ':feature-topic'
 include ':sync'