fix #19481: stop audio on previewer navigation

Author: Ayush-Patel-56

AnkiDroid/src/main/java/com/ichi2/anki/previewer/CardViewerViewModel.kt

@@ -56,13 +56,14 @@ abstract class CardViewerViewModel(
 
     val showingAnswer = savedStateHandle.getMutableStateFlow(KEY_SHOWING_ANSWER, false)
 
-    protected val cardMediaPlayer =
+    protected open val cardMediaPlayer by lazy {
         CardMediaPlayer(
             javascriptEvaluator = { launchCatchingIO { eval.emit(it) } },
             mediaErrorListener = mediaErrorHandler,
         ).also {
             addCloseable(it)
         }
+    }
     abstract var currentCard: Deferred<Card>
 
     abstract val server: AnkiServer

AnkiDroid/src/main/java/com/ichi2/anki/previewer/PreviewerViewModel.kt

@@ -43,9 +43,10 @@ import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
 import timber.log.Timber
 
-class PreviewerViewModel(
+open class PreviewerViewModel(
     savedStateHandle: SavedStateHandle,
 ) : CardViewerViewModel(savedStateHandle),
     ChangeManager.Subscriber {
@@ -115,9 +116,11 @@ class PreviewerViewModel(
         launchCatchingIO {
             backSideOnly.emit(!backSideOnly.value)
             if (!backSideOnly.value && showingAnswer.value) {
+                stopAudio()
                 showQuestion()
                 cardMediaPlayer.autoplayAllForSide(CardSide.QUESTION)
             } else if (backSideOnly.value && !showingAnswer.value) {
+                stopAudio()
                 showAnswer()
                 cardMediaPlayer.autoplayAllForSide(CardSide.ANSWER)
             }
@@ -158,6 +161,7 @@ class PreviewerViewModel(
     fun onNextButtonClick() {
         launchCatchingIO {
             if (!showingAnswer.value && !backSideOnly.value) {
+                stopAudio()
                 showAnswer()
                 cardMediaPlayer.autoplayAllForSide(CardSide.ANSWER)
             } else {
@@ -175,6 +179,7 @@ class PreviewerViewModel(
             if (currentIndex.value > 0) {
                 currentIndex.update { it - 1 }
             } else if (showingAnswer.value && !backSideOnly.value) {
+                stopAudio()
                 showQuestion()
             }
         }
@@ -271,6 +276,10 @@ class PreviewerViewModel(
         }
     }
 
+    private fun stopAudio() {
+        viewModelScope.launch { cardMediaPlayer.stop() }
+    }
+
     companion object {
         private const val KEY_BACKSIDE_ONLY = "backsideOnly"
         private const val KEY_CURRENT_INDEX = "currentIndex"

AnkiDroid/src/test/java/com/ichi2/anki/previewer/PreviewerViewModelTest.kt

@@ -19,15 +19,18 @@ import androidx.lifecycle.SavedStateHandle
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.ichi2.anki.Flag
 import com.ichi2.anki.browser.IdsFile
+import com.ichi2.anki.cardviewer.CardMediaPlayer
 import com.ichi2.anki.servicelayer.NoteService
 import com.ichi2.anki.utils.ext.flag
 import com.ichi2.testutils.JvmTest
 import com.ichi2.testutils.common.Flaky
 import com.ichi2.testutils.common.OS
 import io.mockk.coEvery
+import io.mockk.coVerify
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.spyk
+import io.mockk.verify
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.test.TestScope
 import kotlinx.coroutines.test.advanceUntilIdle
@@ -42,7 +45,13 @@ import org.junit.runner.RunWith
 class PreviewerViewModelTest : JvmTest() {
     private val idsFile: IdsFile = mockk()
 
+    private class InstrumentedPreviewerViewModel(
+        savedStateHandle: SavedStateHandle,
+        override val cardMediaPlayer: CardMediaPlayer,
+    ) : PreviewerViewModel(savedStateHandle)
+
     private lateinit var viewModel: PreviewerViewModel
+    private lateinit var mockMediaPlayer: CardMediaPlayer
 
     private fun TestScope.onNextButtonClick() {
         viewModel.onNextButtonClick()
@@ -79,9 +88,9 @@ class PreviewerViewModelTest : JvmTest() {
                 set(PreviewerFragment.CARD_IDS_FILE_ARG, idsFile)
             }
 
-        viewModel = spyk(PreviewerViewModel(savedStateHandle))
-        // the default implementation requires the Collection media directory,
-        // which needs Robolectric with CollectionStorageMode.IN_MEMORY_WITH_MEDIA or ON_DISK
+        mockMediaPlayer = mockk(relaxed = true)
+        viewModel = spyk(InstrumentedPreviewerViewModel(savedStateHandle, mockMediaPlayer))
+
         coEvery { viewModel.prepareCardTextForDisplay(any()) } answers { firstArg() }
     }
 
@@ -270,4 +279,26 @@ class PreviewerViewModelTest : JvmTest() {
             onSliderChange(sliderPosition = 2)
             assertEquals("Index should update for valid input", 1, viewModel.currentIndex.value)
         }
+
+    @Test
+    fun `audio stops when changing sides`() =
+        runTest {
+            viewModel.onPageFinished(false)
+            viewModel.showingAnswer.value = false
+
+            // 1. Next Button (Question -> Answer)
+            onNextButtonClick()
+            coVerify(atLeast = 1) { mockMediaPlayer.stop() }
+
+            // Reset mocks
+            io.mockk.clearMocks(mockMediaPlayer, answers = false, recordedCalls = true, childMocks = false)
+
+            onPreviousButtonClick()
+            coVerify(atLeast = 1) { mockMediaPlayer.stop() }
+
+            io.mockk.clearMocks(mockMediaPlayer, answers = false, recordedCalls = true, childMocks = false)
+
+            toggleBackSideOnly()
+            coVerify(atLeast = 1) { mockMediaPlayer.stop() }
+        }
 }