Refactor: Move Turbine test to a separate file

This commit refactors the Flow testing snippets by moving the Turbine test to its own file. To avoid code duplication, the  and  classes were moved to a new  file, so they can be shared between tests.

Author: cartland

kotlin/src/test/java/com/android/example/flow/test/RepositoryTest.kt

@@ -16,16 +16,10 @@
 
 package com.android.example.flow.test
 
-import app.cash.turbine.test
-import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.flow
-import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.toList
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.test.UnconfinedTestDispatcher
 import kotlinx.coroutines.test.runTest
 import org.junit.Assert.assertEquals
 import org.junit.Test
@@ -91,65 +85,4 @@ class RepositoryTest {
     }
 }
 
-// [START android_snippets_kotlin_flow_test_repository_and_datasource]
-interface DataSource {
-    fun counts(): Flow<Int>
-}
-
-class Repository(private val dataSource: DataSource) {
-    fun scores(): Flow<Int> {
-        return dataSource.counts().map { it * 10 }
-    }
-}
-
-class FakeDataSource : DataSource {
-    private val flow = MutableSharedFlow<Int>()
-    suspend fun emit(value: Int) = flow.emit(value)
-    override fun counts(): Flow<Int> = flow
-}
-// [END android_snippets_kotlin_flow_test_repository_and_datasource]
-
-@OptIn(ExperimentalCoroutinesApi::class)
-class ContinuousCollectionTest {
-    @Test
-    fun continuouslyCollect() = runTest {
-        // [START android_snippets_kotlin_flow_test_continuously_collect]
-        val dataSource = FakeDataSource()
-        val repository = Repository(dataSource)
 
-        val values = mutableListOf<Int>()
-        backgroundScope.launch(UnconfinedTestDispatcher(testScheduler)) {
-            repository.scores().toList(values)
-        }
-
-        dataSource.emit(1)
-        assertEquals(10, values[0]) // Assert on the list contents
-
-        dataSource.emit(2)
-        dataSource.emit(3)
-        assertEquals(30, values[2])
-
-        assertEquals(3, values.size) // Assert the number of items collected
-        // [END android_snippets_kotlin_flow_test_continuously_collect]
-    }
-
-    @Test
-    fun usingTurbine() = runTest {
-        // [START android_snippets_kotlin_flow_test_using_turbine]
-        val dataSource = FakeDataSource()
-        val repository = Repository(dataSource)
-
-        repository.scores().test {
-            // Make calls that will trigger value changes only within test{}
-            dataSource.emit(1)
-            assertEquals(10, awaitItem())
-
-            dataSource.emit(2)
-            awaitItem() // Ignore items if needed, can also use skip(n)
-
-            dataSource.emit(3)
-            assertEquals(30, awaitItem())
-        }
-        // [END android_snippets_kotlin_flow_test_using_turbine]
-    }
-}

kotlin/src/test/java/com/android/example/flow/test/TurbineTest.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 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
+ *
+ *      http://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.android.example.flow.test
+
+import app.cash.turbine.test
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class TurbineTest {
+    @Test
+    fun usingTurbine() = runTest {
+        // [START android_snippets_kotlin_flow_test_using_turbine]
+        val dataSource = FakeDataSource()
+        val repository = Repository(dataSource)
+
+        repository.scores().test {
+            // Make calls that will trigger value changes only within test{}
+            dataSource.emit(1)
+            assertEquals(10, awaitItem())
+
+            dataSource.emit(2)
+            awaitItem() // Ignore items if needed, can also use skip(n)
+
+            dataSource.emit(3)
+            assertEquals(30, awaitItem())
+        }
+        // [END android_snippets_kotlin_flow_test_using_turbine]
+    }
+}

kotlin/src/test/java/com/android/example/flow/test/ViewModelTest.kt

@@ -65,9 +65,9 @@ class ViewModelTest {
     @get:Rule
     val mainDispatcherRule = MainDispatcherRule()
 
+    // [START android_snippets_kotlin_flow_test_hot_fake_repository]
     @Test
     fun testHotFakeRepository() = runTest {
-        // [START android_snippets_kotlin_flow_test_hot_fake_repository]
         val fakeRepository = FakeRepository()
         val viewModel = MyViewModel(fakeRepository)
 
@@ -83,8 +83,8 @@ class ViewModelTest {
         fakeRepository.emit(2)
         fakeRepository.emit(3)
         assertEquals(3, viewModel.score.value) // Assert on the latest value
-        // [END android_snippets_kotlin_flow_test_hot_fake_repository]
     }
+    // [END android_snippets_kotlin_flow_test_hot_fake_repository]
 }
 
 // [START android_snippets_kotlin_flow_test_my_view_model_with_state_in]
@@ -101,9 +101,9 @@ class LazilySharingViewModelTest {
     @get:Rule
     val mainDispatcherRule = MainDispatcherRule()
 
+    // [START android_snippets_kotlin_flow_test_lazily_sharing_view_model]
     @Test
     fun testLazilySharingViewModel() = runTest {
-        // [START android_snippets_kotlin_flow_test_lazily_sharing_view_model]
         val fakeRepository = HotFakeRepository()
         val viewModel = MyViewModelWithStateIn(fakeRepository)
 
@@ -121,6 +121,6 @@ class LazilySharingViewModelTest {
         fakeRepository.emit(2)
         fakeRepository.emit(3)
         assertEquals(3, viewModel.score.value)
-        // [END android_snippets_kotlin_flow_test_lazily_sharing_view_model]
     }
+    // [END android_snippets_kotlin_flow_test_lazily_sharing_view_model]
 }

kotlin/src/test/java/com/android/example/flow/test/fakes.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 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
+ *
+ *      http://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.android.example.flow.test
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.map
+
+// [START android_snippets_kotlin_flow_test_repository_and_datasource]
+interface DataSource {
+    fun counts(): Flow<Int>
+}
+
+class Repository(private val dataSource: DataSource) {
+    fun scores(): Flow<Int> {
+        return dataSource.counts().map { it * 10 }
+    }
+}
+
+class FakeDataSource : DataSource {
+    private val flow = MutableSharedFlow<Int>()
+    suspend fun emit(value: Int) = flow.emit(value)
+    override fun counts(): Flow<Int> = flow
+}
+// [END android_snippets_kotlin_flow_test_repository_and_datasource]