Merge "Update Main dispatcher rule, assert on StateFlow's value property" into main

core-testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/util/MainDispatcherRule.kt

@@ -16,31 +16,27 @@
 
 package com.google.samples.apps.nowinandroid.core.testing.util
 
-import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.TestDispatcher
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
 import kotlinx.coroutines.test.resetMain
 import kotlinx.coroutines.test.setMain
 import org.junit.rules.TestRule
+import org.junit.rules.TestWatcher
 import org.junit.runner.Description
-import org.junit.runners.model.Statement
 
 /**
- * A [TestRule] that initializes the main dispatcher to [dispatcher], which defaults to a
+ * A JUnit [TestRule] that sets the Main dispatcher to [testDispatcher]
- * [StandardTestDispatcher].
+ * for the duration of the test.
  */
-class TestDispatcherRule(
+class MainDispatcherRule(
-    private val dispatcher: CoroutineDispatcher = StandardTestDispatcher()
+    val testDispatcher: TestDispatcher = UnconfinedTestDispatcher(),
-) : TestRule {
+) : TestWatcher() {
-    override fun apply(base: Statement, description: Description): Statement =
+    override fun starting(description: Description) {
-        object : Statement() {
+        Dispatchers.setMain(testDispatcher)
-            override fun evaluate() {
-                Dispatchers.setMain(dispatcher)
-                try {
-                    base.evaluate()
-                } finally {
-                    Dispatchers.resetMain()
-                }
     }
+
+    override fun finished(description: Description) {
+        Dispatchers.resetMain()
     }
 }

feature-author/src/test/java/com/google/samples/apps/nowinandroid/feature/author/AuthorViewModelTest.kt

@@ -17,7 +17,6 @@
 package com.google.samples.apps.nowinandroid.feature.author
 
 import androidx.lifecycle.SavedStateHandle
-import app.cash.turbine.test
 import com.google.samples.apps.nowinandroid.core.model.data.Author
 import com.google.samples.apps.nowinandroid.core.model.data.FollowableAuthor
 import com.google.samples.apps.nowinandroid.core.model.data.NewsResource
@@ -25,9 +24,12 @@ import com.google.samples.apps.nowinandroid.core.model.data.NewsResourceType.Vid
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestAuthorsRepository
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestNewsRepository
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestUserDataRepository
-import com.google.samples.apps.nowinandroid.core.testing.util.TestDispatcherRule
+import com.google.samples.apps.nowinandroid.core.testing.util.MainDispatcherRule
 import com.google.samples.apps.nowinandroid.feature.author.navigation.AuthorDestination
+import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
 import kotlinx.coroutines.test.runTest
 import kotlinx.datetime.Instant
 import org.junit.Assert.assertEquals
@@ -36,10 +38,14 @@ import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 
+/**
+ * To learn more about how this test handles Flows created with stateIn, see
+ * https://developer.android.com/kotlin/flow/test#statein
+ */
 class AuthorViewModelTest {
 
     @get:Rule
-    val dispatcherRule = TestDispatcherRule()
+    val dispatcherRule = MainDispatcherRule()
 
     private val userDataRepository = TestUserDataRepository()
     private val authorsRepository = TestAuthorsRepository()
@@ -62,13 +68,13 @@ class AuthorViewModelTest {
 
     @Test
     fun uiStateAuthor_whenSuccess_matchesAuthorFromRepository() = runTest {
-        viewModel.uiState.test {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-            awaitItem()
+
         // To make sure AuthorUiState is success
         authorsRepository.sendAuthors(testInputAuthors.map(FollowableAuthor::author))
         userDataRepository.setFollowedAuthorIds(setOf(testInputAuthors[1].author.id))
 
-            val item = awaitItem()
+        val item = viewModel.uiState.value
         assertTrue(item.authorState is AuthorUiState.Success)
 
         val successAuthorUiState = item.authorState as AuthorUiState.Success
@@ -78,63 +84,63 @@ class AuthorViewModelTest {
 
         successAuthorUiState.followableAuthor.author
         assertEquals(authorFromRepository, successAuthorUiState.followableAuthor.author)
-        }
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiStateNews_whenInitialized_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        assertEquals(NewsUiState.Loading, viewModel.uiState.value.newsState)
-            assertEquals(NewsUiState.Loading, awaitItem().newsState)
-        }
     }
 
     @Test
     fun uiStateAuthor_whenInitialized_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        assertEquals(AuthorUiState.Loading, viewModel.uiState.value.authorState)
-            assertEquals(AuthorUiState.Loading, awaitItem().authorState)
-        }
     }
 
     @Test
     fun uiStateAuthor_whenFollowedIdsSuccessAndAuthorLoading_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
+
         userDataRepository.setFollowedAuthorIds(setOf(testInputAuthors[1].author.id))
-            assertEquals(AuthorUiState.Loading, awaitItem().authorState)
+        assertEquals(AuthorUiState.Loading, viewModel.uiState.value.authorState)
-        }
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiStateAuthor_whenFollowedIdsSuccessAndAuthorSuccess_thenAuthorSuccessAndNewsLoading() =
         runTest {
-            viewModel.uiState.test {
+            val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-                awaitItem()
+
             authorsRepository.sendAuthors(testInputAuthors.map { it.author })
             userDataRepository.setFollowedAuthorIds(setOf(testInputAuthors[1].author.id))
-                val item = awaitItem()
+            val item = viewModel.uiState.value
             assertTrue(item.authorState is AuthorUiState.Success)
             assertTrue(item.newsState is NewsUiState.Loading)
-            }
+
+            collectJob.cancel()
         }
 
     @Test
     fun uiStateAuthor_whenFollowedIdsSuccessAndAuthorSuccessAndNewsIsSuccess_thenAllSuccess() =
         runTest {
-            viewModel.uiState.test {
+            val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-                awaitItem()
+
             authorsRepository.sendAuthors(testInputAuthors.map { it.author })
             userDataRepository.setFollowedAuthorIds(setOf(testInputAuthors[1].author.id))
             newsRepository.sendNewsResources(sampleNewsResources)
-                val item = awaitItem()
+            val item = viewModel.uiState.value
             assertTrue(item.authorState is AuthorUiState.Success)
             assertTrue(item.newsState is NewsUiState.Success)
-            }
+
+            collectJob.cancel()
         }
 
     @Test
     fun uiStateAuthor_whenFollowingAuthor_thenShowUpdatedAuthor() = runTest {
-        viewModel.uiState
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-            .test {
+
-                awaitItem()
         authorsRepository.sendAuthors(testInputAuthors.map { it.author })
         // Set which author IDs are followed, not including 0.
         userDataRepository.setFollowedAuthorIds(setOf(testInputAuthors[1].author.id))
@@ -143,9 +149,10 @@ class AuthorViewModelTest {
 
         assertEquals(
             AuthorUiState.Success(followableAuthor = testOutputAuthors[0]),
-                    awaitItem().authorState
+            viewModel.uiState.value.authorState
         )
-            }
+
+        collectJob.cancel()
     }
 }
 

feature-interests/src/test/java/com/google/samples/apps/nowinandroid/interests/InterestsViewModelTest.kt

@@ -16,7 +16,6 @@
 
 package com.google.samples.apps.nowinandroid.interests
 
-import app.cash.turbine.test
 import com.google.samples.apps.nowinandroid.core.model.data.Author
 import com.google.samples.apps.nowinandroid.core.model.data.FollowableAuthor
 import com.google.samples.apps.nowinandroid.core.model.data.FollowableTopic
@@ -24,19 +23,26 @@ import com.google.samples.apps.nowinandroid.core.model.data.Topic
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestAuthorsRepository
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestTopicsRepository
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestUserDataRepository
-import com.google.samples.apps.nowinandroid.core.testing.util.TestDispatcherRule
+import com.google.samples.apps.nowinandroid.core.testing.util.MainDispatcherRule
 import com.google.samples.apps.nowinandroid.feature.interests.InterestsUiState
 import com.google.samples.apps.nowinandroid.feature.interests.InterestsViewModel
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
 import kotlinx.coroutines.test.runTest
 import org.junit.Assert.assertEquals
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 
+/**
+ * To learn more about how this test handles Flows created with stateIn, see
+ * https://developer.android.com/kotlin/flow/test#statein
+ */
 class InterestsViewModelTest {
 
     @get:Rule
-    val dispatcherRule = TestDispatcherRule()
+    val mainDispatcherRule = MainDispatcherRule()
 
     private val userDataRepository = TestUserDataRepository()
     private val authorsRepository = TestAuthorsRepository()
@@ -54,35 +60,36 @@ class InterestsViewModelTest {
 
     @Test
     fun uiState_whenInitialized_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        assertEquals(InterestsUiState.Loading, viewModel.uiState.value)
-            assertEquals(InterestsUiState.Loading, awaitItem())
-        }
     }
 
     @Test
     fun uiState_whenFollowedTopicsAreLoading_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-            assertEquals(InterestsUiState.Loading, awaitItem())
+
         userDataRepository.setFollowedAuthorIds(setOf("1"))
         userDataRepository.setFollowedTopicIds(emptySet())
-        }
+        assertEquals(InterestsUiState.Loading, viewModel.uiState.value)
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiState_whenFollowedAuthorsAreLoading_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-            assertEquals(InterestsUiState.Loading, awaitItem())
+
         userDataRepository.setFollowedAuthorIds(emptySet())
         userDataRepository.setFollowedTopicIds(setOf("1"))
-        }
+        assertEquals(InterestsUiState.Loading, viewModel.uiState.value)
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiState_whenFollowingNewTopic_thenShowUpdatedTopics() = runTest {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
+
         val toggleTopicId = testOutputTopics[1].topic.id
-        viewModel.uiState
-            .test {
-                awaitItem()
         authorsRepository.sendAuthors(emptyList())
         userDataRepository.setFollowedAuthorIds(emptySet())
         topicsRepository.sendTopics(testInputTopics.map { it.topic })
@@ -90,7 +97,7 @@ class InterestsViewModelTest {
 
         assertEquals(
             false,
-                    (awaitItem() as InterestsUiState.Interests)
+            (viewModel.uiState.value as InterestsUiState.Interests)
                 .topics.first { it.topic.id == toggleTopicId }.isFollowed
         )
 
@@ -101,22 +108,21 @@ class InterestsViewModelTest {
 
         assertEquals(
             InterestsUiState.Interests(topics = testOutputTopics, authors = emptyList()),
-                    awaitItem()
+            viewModel.uiState.value
         )
-            }
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiState_whenFollowingNewAuthor_thenShowUpdatedAuthors() = runTest {
-        viewModel.uiState
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-            .test {
+
-                awaitItem()
         authorsRepository.sendAuthors(testInputAuthors.map { it.author })
         userDataRepository.setFollowedAuthorIds(setOf(testInputAuthors[0].author.id))
         topicsRepository.sendTopics(listOf())
         userDataRepository.setFollowedTopicIds(setOf())
 
-                awaitItem()
         viewModel.followAuthor(
             followedAuthorId = testInputAuthors[1].author.id,
             followed = true
@@ -124,17 +130,18 @@ class InterestsViewModelTest {
 
         assertEquals(
             InterestsUiState.Interests(topics = emptyList(), authors = testOutputAuthors),
-                    awaitItem()
+            viewModel.uiState.value
         )
-            }
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiState_whenUnfollowingTopics_thenShowUpdatedTopics() = runTest {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
+
         val toggleTopicId = testOutputTopics[1].topic.id
-        viewModel.uiState
+
-            .test {
-                awaitItem()
         authorsRepository.sendAuthors(emptyList())
         userDataRepository.setFollowedAuthorIds(emptySet())
         topicsRepository.sendTopics(testOutputTopics.map { it.topic })
@@ -144,7 +151,7 @@ class InterestsViewModelTest {
 
         assertEquals(
             true,
-                    (awaitItem() as InterestsUiState.Interests)
+            (viewModel.uiState.value as InterestsUiState.Interests)
                 .topics.first { it.topic.id == toggleTopicId }.isFollowed
         )
 
@@ -155,16 +162,16 @@ class InterestsViewModelTest {
 
         assertEquals(
             InterestsUiState.Interests(topics = testInputTopics, authors = emptyList()),
-                    awaitItem()
+            viewModel.uiState.value
         )
-            }
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiState_whenUnfollowingAuthors_thenShowUpdatedAuthors() = runTest {
-        viewModel.uiState
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-            .test {
+
-                awaitItem()
         authorsRepository.sendAuthors(testOutputAuthors.map { it.author })
         userDataRepository.setFollowedAuthorIds(
             setOf(testOutputAuthors[0].author.id, testOutputAuthors[1].author.id)
@@ -172,7 +179,6 @@ class InterestsViewModelTest {
         topicsRepository.sendTopics(listOf())
         userDataRepository.setFollowedTopicIds(setOf())
 
-                awaitItem()
         viewModel.followAuthor(
             followedAuthorId = testOutputAuthors[1].author.id,
             followed = false
@@ -180,9 +186,10 @@ class InterestsViewModelTest {
 
         assertEquals(
             InterestsUiState.Interests(topics = emptyList(), authors = testInputAuthors),
-                    awaitItem()
+            viewModel.uiState.value
         )
-            }
+
+        collectJob.cancel()
     }
 }
 

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

@@ -17,7 +17,6 @@
 package com.google.samples.apps.nowinandroid.feature.topic
 
 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
@@ -25,9 +24,12 @@ 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.repository.TestUserDataRepository
-import com.google.samples.apps.nowinandroid.core.testing.util.TestDispatcherRule
+import com.google.samples.apps.nowinandroid.core.testing.util.MainDispatcherRule
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.TopicDestination
+import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
 import kotlinx.coroutines.test.runTest
 import kotlinx.datetime.Instant
 import org.junit.Assert.assertEquals
@@ -36,10 +38,14 @@ import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 
+/**
+ * To learn more about how this test handles Flows created with stateIn, see
+ * https://developer.android.com/kotlin/flow/test#statein
+ */
 class TopicViewModelTest {
 
     @get:Rule
-    val dispatcherRule = TestDispatcherRule()
+    val dispatcherRule = MainDispatcherRule()
 
     private val userDataRepository = TestUserDataRepository()
     private val topicsRepository = TestTopicsRepository()
@@ -59,11 +65,11 @@ class TopicViewModelTest {
 
     @Test
     fun uiStateAuthor_whenSuccess_matchesTopicFromRepository() = runTest {
-        viewModel.uiState.test {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-            awaitItem()
+
         topicsRepository.sendTopics(testInputTopics.map(FollowableTopic::topic))
         userDataRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
-            val item = awaitItem()
+        val item = viewModel.uiState.value
         assertTrue(item.topicState is TopicUiState.Success)
 
         val successTopicState = item.topicState as TopicUiState.Success
@@ -72,63 +78,63 @@ class TopicViewModelTest {
         ).first()
 
         assertEquals(topicFromRepository, successTopicState.followableTopic.topic)
-        }
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiStateNews_whenInitialized_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        assertEquals(NewsUiState.Loading, viewModel.uiState.value.newsState)
-            assertEquals(NewsUiState.Loading, awaitItem().newsState)
-        }
     }
 
     @Test
     fun uiStateTopic_whenInitialized_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        assertEquals(TopicUiState.Loading, viewModel.uiState.value.topicState)
-            assertEquals(TopicUiState.Loading, awaitItem().topicState)
-        }
     }
 
     @Test
     fun uiStateTopic_whenFollowedIdsSuccessAndTopicLoading_thenShowLoading() = runTest {
-        viewModel.uiState.test {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
+
         userDataRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
-            assertEquals(TopicUiState.Loading, awaitItem().topicState)
+        assertEquals(TopicUiState.Loading, viewModel.uiState.value.topicState)
-        }
+
+        collectJob.cancel()
     }
 
     @Test
     fun uiStateTopic_whenFollowedIdsSuccessAndTopicSuccess_thenTopicSuccessAndNewsLoading() =
         runTest {
-            viewModel.uiState.test {
+            val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-                awaitItem()
+
             topicsRepository.sendTopics(testInputTopics.map { it.topic })
             userDataRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
-                val item = awaitItem()
+            val item = viewModel.uiState.value
             assertTrue(item.topicState is TopicUiState.Success)
             assertTrue(item.newsState is NewsUiState.Loading)
-            }
+
+            collectJob.cancel()
         }
 
     @Test
     fun uiStateTopic_whenFollowedIdsSuccessAndTopicSuccessAndNewsIsSuccess_thenAllSuccess() =
         runTest {
-            viewModel.uiState.test {
+            val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-                awaitItem()
+
             topicsRepository.sendTopics(testInputTopics.map { it.topic })
             userDataRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
             newsRepository.sendNewsResources(sampleNewsResources)
-                val item = awaitItem()
+            val item = viewModel.uiState.value
             assertTrue(item.topicState is TopicUiState.Success)
             assertTrue(item.newsState is NewsUiState.Success)
-            }
+
+            collectJob.cancel()
         }
 
     @Test
     fun uiStateTopic_whenFollowingTopic_thenShowUpdatedTopic() = runTest {
-        viewModel.uiState
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.uiState.collect() }
-            .test {
+
-                awaitItem()
         topicsRepository.sendTopics(testInputTopics.map { it.topic })
         // Set which topic IDs are followed, not including 0.
         userDataRepository.setFollowedTopicIds(setOf(testInputTopics[1].topic.id))
@@ -137,9 +143,10 @@ class TopicViewModelTest {
 
         assertEquals(
             TopicUiState.Success(followableTopic = testOutputTopics[0]),
-                    awaitItem().topicState
+            viewModel.uiState.value.topicState
         )
-            }
+
+        collectJob.cancel()
     }
 }