Bug 1862289 - Translations UI Integration Low Data Translate

app/src/main/java/org/mozilla/fenix/translations/TranslationsDialogBinding.kt

@@ -77,12 +77,14 @@ class TranslationsDialogBinding(
 
                 // Session Translations State Behavior (Tab)
                 val sessionTranslationsState = state.sessionState.translationsState
+
                 val fromSelected =
                     sessionTranslationsState.translationEngineState?.initialFromLanguage(
                         translateFromLanguages,
                     )
 
-                fromSelected?.let {
+                // Dispatch initialFrom Language only the first time when it is null.
+                if (fromSelected != null && translationsDialogStore.state.initialFrom == null) {
                     translationsDialogStore.dispatch(
                         TranslationsDialogAction.UpdateFromSelectedLanguage(
                             fromSelected,
@@ -94,7 +96,9 @@ class TranslationsDialogBinding(
                     sessionTranslationsState.translationEngineState?.initialToLanguage(
                         translateToLanguages,
                     )
-                toSelected?.let {
+
+                // Dispatch initialTo Language only the first time when it is null.
+                if (toSelected != null && translationsDialogStore.state.initialTo == null) {
                     translationsDialogStore.dispatch(
                         TranslationsDialogAction.UpdateToSelectedLanguage(
                             toSelected,
@@ -130,6 +134,12 @@ class TranslationsDialogBinding(
                         TranslationsDialogAction.UpdateTranslationError(sessionTranslationsState.translationError),
                     )
                 }
+
+                sessionTranslationsState.translationDownloadSize?.let {
+                    translationsDialogStore.dispatch(
+                        TranslationsDialogAction.UpdateDownloadTranslationDownloadSize(it),
+                    )
+                }
             }
     }
 
@@ -153,11 +163,13 @@ class TranslationsDialogBinding(
             ),
         )
 
-        translationsDialogStore.dispatch(
-            TranslationsDialogAction.UpdateTranslated(
-                true,
-            ),
-        )
+        if (!translationsDialogStore.state.isTranslated) {
+            translationsDialogStore.dispatch(
+                TranslationsDialogAction.UpdateTranslated(
+                    true,
+                ),
+            )
+        }
 
         if (translationsDialogStore.state.dismissDialogState == DismissDialogState.WaitingToBeDismissed) {
             translationsDialogStore.dispatch(

app/src/main/java/org/mozilla/fenix/translations/TranslationsDialogFragment.kt

@@ -35,10 +35,14 @@ import mozilla.components.support.base.feature.ViewBoundFeatureWrapper
 import org.mozilla.fenix.BrowserDirection
 import org.mozilla.fenix.HomeActivity
 import org.mozilla.fenix.R
+import org.mozilla.fenix.ext.components
 import org.mozilla.fenix.ext.requireComponents
 import org.mozilla.fenix.ext.settings
 import org.mozilla.fenix.settings.SupportUtils
 import org.mozilla.fenix.theme.FirefoxTheme
+import org.mozilla.fenix.translations.preferences.downloadlanguages.DownloadLanguageFileDialog
+import org.mozilla.fenix.translations.preferences.downloadlanguages.DownloadLanguageFileDialogType
+import org.mozilla.fenix.translations.preferences.downloadlanguages.DownloadLanguagesFeature
 
 /**
  * The enum is to know what bottom sheet to open.
@@ -56,8 +60,11 @@ class TranslationsDialogFragment : BottomSheetDialogFragment() {
     private val args by navArgs<TranslationsDialogFragmentArgs>()
     private val browserStore: BrowserStore by lazy { requireComponents.core.store }
     private val translationDialogBinding = ViewBoundFeatureWrapper<TranslationsDialogBinding>()
+    private val downloadLanguagesFeature =
+        ViewBoundFeatureWrapper<DownloadLanguagesFeature>()
     private lateinit var translationsDialogStore: TranslationsDialogStore
     private var isTranslationInProgress: Boolean? = null
+    private var isDataSaverEnabledAndWifiDisabled = false
 
     override fun onCreateDialog(savedInstanceState: Bundle?): Dialog =
         super.onCreateDialog(savedInstanceState).apply {
@@ -192,9 +199,22 @@ class TranslationsDialogFragment : BottomSheetDialogFragment() {
             view = view,
         )
         translationsDialogStore.dispatch(TranslationsDialogAction.InitTranslationsDialog)
+
+        downloadLanguagesFeature.set(
+            feature = DownloadLanguagesFeature(
+                context = requireContext(),
+                wifiConnectionMonitor = requireContext().components.wifiConnectionMonitor,
+                onDataSaverAndWifiChanged = {
+                    isDataSaverEnabledAndWifiDisabled = it
+                },
+            ),
+            owner = this,
+            view = view,
+        )
     }
 
     @Composable
+    @Suppress("LongMethod")
     private fun TranslationsDialogContent(learnMoreUrl: String, onSettingClicked: () -> Unit) {
         val translationsDialogState =
             translationsDialogStore.observeAsComposableState { it }.value
@@ -206,6 +226,10 @@ class TranslationsDialogFragment : BottomSheetDialogFragment() {
                 dismissDialog()
             }
 
+            var showDownloadLanguageFileDialog by remember {
+                mutableStateOf(false)
+            }
+
             TranslationsDialog(
                 translationsDialogState = translationsDialogState,
                 learnMoreUrl = learnMoreUrl,
@@ -216,7 +240,15 @@ class TranslationsDialogFragment : BottomSheetDialogFragment() {
                     if (state.error is TranslationError.CouldNotLoadLanguagesError) {
                         translationsDialogStore.dispatch(TranslationsDialogAction.FetchSupportedLanguages)
                     } else {
-                        translationsDialogStore.dispatch(TranslationsDialogAction.TranslateAction)
+                        if (
+                            isDataSaverEnabledAndWifiDisabled &&
+                            !requireContext().settings().ignoreTranslationsDataSaverWarning &&
+                            state.translationDownloadSize != null
+                        ) {
+                            showDownloadLanguageFileDialog = true
+                        } else {
+                            translationsDialogStore.dispatch(TranslationsDialogAction.TranslateAction)
+                        }
                     }
                 },
                 onNegativeButtonClicked = {
@@ -225,21 +257,58 @@ class TranslationsDialogFragment : BottomSheetDialogFragment() {
                     }
                     dismiss()
                 },
-                onFromSelected = {
+                onFromSelected = { fromLanguage ->
+                    state.initialTo?.let {
+                        translationsDialogStore.dispatch(
+                            TranslationsDialogAction.FetchDownloadFileSizeAction(
+                                toLanguage = it,
+                                fromLanguage = fromLanguage,
+                            ),
+                        )
+                    }
+
                     translationsDialogStore.dispatch(
                         TranslationsDialogAction.UpdateFromSelectedLanguage(
-                            it,
+                            fromLanguage,
                         ),
                     )
                 },
-                onToSelected = {
+                onToSelected = { toLanguage ->
+                    state.initialFrom?.let {
+                        translationsDialogStore.dispatch(
+                            TranslationsDialogAction.FetchDownloadFileSizeAction(
+                                toLanguage = toLanguage,
+                                fromLanguage = it,
+                            ),
+                        )
+                    }
+
                     translationsDialogStore.dispatch(
                         TranslationsDialogAction.UpdateToSelectedLanguage(
-                            it,
+                            toLanguage,
                         ),
                     )
                 },
             )
+
+            var checkBoxEnabled by remember { mutableStateOf(false) }
+            if (showDownloadLanguageFileDialog) {
+                state.translationDownloadSize?.size?.let { fileSize ->
+                    DownloadLanguageFileDialog(
+                        downloadLanguageDialogType = DownloadLanguageFileDialogType.TranslationRequest,
+                        fileSize = fileSize,
+                        isCheckBoxEnabled = checkBoxEnabled,
+                        onSavingModeStateChange = { checkBoxEnabled = it },
+                        onConfirmDownload = {
+                            requireContext().settings().ignoreTranslationsDataSaverWarning =
+                                checkBoxEnabled
+                            showDownloadLanguageFileDialog = false
+                            translationsDialogStore.dispatch(TranslationsDialogAction.TranslateAction)
+                        },
+                        onCancel = { showDownloadLanguageFileDialog = false },
+                    )
+                }
+            }
         }
     }
 

app/src/main/java/org/mozilla/fenix/translations/TranslationsDialogMiddleware.kt

@@ -24,6 +24,16 @@ class TranslationsDialogMiddleware(
         action: TranslationsDialogAction,
     ) {
         when (action) {
+            is TranslationsDialogAction.FetchDownloadFileSizeAction -> {
+                browserStore.dispatch(
+                    TranslationsAction.FetchTranslationDownloadSizeAction(
+                        tabId = sessionId,
+                        fromLanguage = action.fromLanguage,
+                        toLanguage = action.toLanguage,
+                    ),
+                )
+            }
+
             is TranslationsDialogAction.FetchSupportedLanguages -> {
                 browserStore.dispatch(
                     TranslationsAction.OperationRequestedAction(

app/src/main/java/org/mozilla/fenix/translations/TranslationsDialogStore.kt

@@ -6,6 +6,7 @@ package org.mozilla.fenix.translations
 import mozilla.components.browser.state.action.TranslationsAction
 import mozilla.components.browser.state.store.BrowserStore
 import mozilla.components.concept.engine.translate.Language
+import mozilla.components.concept.engine.translate.TranslationDownloadSize
 import mozilla.components.concept.engine.translate.TranslationError
 import mozilla.components.lib.state.Action
 import mozilla.components.lib.state.Middleware
@@ -33,6 +34,8 @@ class TranslationsDialogStore(
  * @property isTranslated The page is currently translated.
  * @property isTranslationInProgress The page is currently attempting a translation.
  * @property positiveButtonType Can be enabled,disabled or in progress.
+ * @property translationDownloadSize A data class to contain information
+ * related to the download size required for a given translation to/from pair.
  * @property error An error that can occur during the translation process.
  * @property dismissDialogState Whether the dialog bottom sheet should be dismissed.
  * @property initialFrom Initial "from" language, based on the translation state and page state.
@@ -45,6 +48,7 @@ data class TranslationsDialogState(
     var isTranslated: Boolean = false,
     val isTranslationInProgress: Boolean = false,
     val positiveButtonType: PositiveButtonType? = null,
+    val translationDownloadSize: TranslationDownloadSize? = null,
     val error: TranslationError? = null,
     val dismissDialogState: DismissDialogState? = null,
     val initialFrom: Language? = null,
@@ -139,6 +143,18 @@ sealed class TranslationsDialogAction : Action {
      * Updates the dialog title if the page was translated.
      */
     data class UpdateTranslatedPageTitle(val title: String) : TranslationsDialogAction()
+
+    /**
+     * Updates the translation download file size.
+     */
+    data class UpdateDownloadTranslationDownloadSize(val translationDownloadSize: TranslationDownloadSize? = null) :
+        TranslationsDialogAction()
+
+    /**
+     * Fetch the translation download file size.
+     */
+    data class FetchDownloadFileSizeAction(val toLanguage: Language, val fromLanguage: Language) :
+        TranslationsDialogAction()
 }
 
 /**
@@ -248,9 +264,7 @@ internal object TranslationsDialogReducer {
             is TranslationsDialogAction.UpdateTranslationError -> {
                 state.copy(
                     error = action.translationError,
-                    positiveButtonType = if (
-                        action.translationError is TranslationError.LanguageNotSupportedError
-                    ) {
+                    positiveButtonType = if (action.translationError is TranslationError.LanguageNotSupportedError) {
                         PositiveButtonType.Disabled
                     } else {
                         PositiveButtonType.Enabled
@@ -269,13 +283,32 @@ internal object TranslationsDialogReducer {
                 state.copy(translatedPageTitle = action.title)
             }
 
+            is TranslationsDialogAction.UpdateDownloadTranslationDownloadSize -> {
+                state.copy(
+                    translationDownloadSize = if (
+                        action.translationDownloadSize?.fromLanguage == state.initialFrom &&
+                        action.translationDownloadSize?.toLanguage == state.initialTo &&
+                        isTranslationDownloadSizeValid(action.translationDownloadSize)
+                    ) {
+                        action.translationDownloadSize
+                    } else {
+                        null
+                    },
+                )
+            }
+
             is TranslationsDialogAction.TranslateAction,
             TranslationsDialogAction.FetchSupportedLanguages,
             TranslationsDialogAction.RestoreTranslation,
+            is TranslationsDialogAction.FetchDownloadFileSizeAction,
             -> {
                 // handled by [TranslationsDialogMiddleware]
                 state
             }
         }
     }
+
+    private fun isTranslationDownloadSizeValid(translationDownloadSize: TranslationDownloadSize?) =
+        translationDownloadSize?.size != 0L &&
+            translationDownloadSize?.error == null
 }

app/src/main/java/org/mozilla/fenix/translations/preferences/downloadlanguages/DownloadLanguageFileDialog.kt

@@ -36,19 +36,19 @@ import org.mozilla.fenix.theme.FirefoxTheme
 
 /**
  * Download Languages File Dialog.
- *
+ * @param downloadLanguageDialogType Whether the download language file item is
+ * of type all languages,single file translation request or default.
  * @param fileSize Language file size in bytes that should be displayed in the dialogue title.
  * @param isCheckBoxEnabled Whether saving mode checkbox is checked or unchecked.
- * @param isAllLanguagesItemType Whether the download language file item is of type all languages.
  * @param onSavingModeStateChange Invoked when the user clicks on the checkbox of the saving mode state.
  * @param onConfirmDownload Invoked when the user click on the "Download" dialog button.
  * @param onCancel Invoked when the user clicks on the "Cancel" dialog button.
  */
 @Composable
 fun DownloadLanguageFileDialog(
+    downloadLanguageDialogType: DownloadLanguageFileDialogType,
     fileSize: Long,
     isCheckBoxEnabled: Boolean,
-    isAllLanguagesItemType: Boolean,
     onSavingModeStateChange: (Boolean) -> Unit,
     onConfirmDownload: () -> Unit,
     onCancel: () -> Unit,
@@ -62,18 +62,29 @@ fun DownloadLanguageFileDialog(
                 )
                 .padding(16.dp),
         ) {
+            val title =
+                if (downloadLanguageDialogType is DownloadLanguageFileDialogType.TranslationRequest) {
+                    stringResource(
+                        R.string.translations_download_language_file_dialog_title,
+                        fileSize.toMegabyteOrKilobyteString(),
+                    )
+                } else {
+                    stringResource(
+                        R.string.download_language_file_dialog_title,
+                        fileSize.toMegabyteOrKilobyteString(),
+                    )
+                }
             Text(
-                text = stringResource(
-                    R.string.download_language_file_dialog_title,
-                    fileSize.toMegabyteOrKilobyteString(),
-                ),
+                text = title,
                 modifier = Modifier
                     .semantics { heading() },
                 color = FirefoxTheme.colors.textPrimary,
                 style = FirefoxTheme.typography.headline7,
             )
 
-            if (isAllLanguagesItemType) {
+            if (downloadLanguageDialogType is DownloadLanguageFileDialogType.AllLanguages ||
+                downloadLanguageDialogType is DownloadLanguageFileDialogType.TranslationRequest
+            ) {
                 Text(
                     text = stringResource(
                         R.string.download_language_file_dialog_message_all_languages,
@@ -89,11 +100,14 @@ fun DownloadLanguageFileDialog(
                 onSavingModeStateChange = onSavingModeStateChange,
             )
 
-            val primaryButtonText: String = if (isAllLanguagesItemType) {
-                stringResource(id = R.string.download_language_file_dialog_positive_button_text_all_languages)
-            } else {
-                stringResource(id = R.string.download_language_file_dialog_positive_button_text)
-            }
+            val primaryButtonText: String =
+                if (downloadLanguageDialogType is DownloadLanguageFileDialogType.AllLanguages ||
+                    downloadLanguageDialogType is DownloadLanguageFileDialogType.TranslationRequest
+                ) {
+                    stringResource(id = R.string.download_language_file_dialog_positive_button_text_all_languages)
+                } else {
+                    stringResource(id = R.string.download_language_file_dialog_positive_button_text)
+                }
 
             PrimaryButton(
                 text = primaryButtonText,
@@ -163,9 +177,9 @@ private fun DownloadLanguageFileDialogCheckbox(
 private fun PrefDownloadLanguageFileDialogPreviewAllLanguages() {
     FirefoxTheme {
         DownloadLanguageFileDialog(
+            downloadLanguageDialogType = DownloadLanguageFileDialogType.AllLanguages,
             fileSize = 4000L,
             isCheckBoxEnabled = true,
-            isAllLanguagesItemType = true,
             onSavingModeStateChange = {},
             onConfirmDownload = {},
             onCancel = {},
@@ -173,14 +187,37 @@ private fun PrefDownloadLanguageFileDialogPreviewAllLanguages() {
     }
 }
 
+/**
+ *  Download Languages File Dialog Type.
+ */
+sealed class DownloadLanguageFileDialogType {
+
+    /**
+     * All language files need to be downloaded.
+     */
+    data object AllLanguages : DownloadLanguageFileDialogType()
+
+    /**
+     * Only one language package needs to be downloaded.
+     */
+    data object Default : DownloadLanguageFileDialogType()
+
+    /**
+     * When the user presses the translate button, the site needs to be translated.
+     * To perform this translation, the device will need to download a language model to perform
+     * this specific translation, if not already downloaded.
+     */
+    data object TranslationRequest : DownloadLanguageFileDialogType()
+}
+
 @Composable
 @LightDarkPreview
 private fun PrefDownloadLanguageFileDialogPreview() {
     FirefoxTheme {
         DownloadLanguageFileDialog(
+            downloadLanguageDialogType = DownloadLanguageFileDialogType.Default,
             fileSize = 4000L,
             isCheckBoxEnabled = false,
-            isAllLanguagesItemType = false,
             onSavingModeStateChange = {},
             onConfirmDownload = {},
             onCancel = {},

app/src/main/java/org/mozilla/fenix/translations/preferences/downloadlanguages/LanguageDialogPreferenceFragment.kt

@@ -74,10 +74,15 @@ class LanguageDialogPreferenceFragment : DialogFragment() {
                 FirefoxTheme {
                     var checkBoxEnabled by remember { mutableStateOf(false) }
                     DownloadLanguageFileDialog(
+                        downloadLanguageDialogType = if (args.downloadLanguageItemStatePreference.type ==
+                            DownloadLanguageItemTypePreference.AllLanguages
+                        ) {
+                            DownloadLanguageFileDialogType.AllLanguages
+                        } else {
+                            DownloadLanguageFileDialogType.Default
+                        },
                         fileSize = args.itemFileSizePreference,
                         isCheckBoxEnabled = checkBoxEnabled,
-                        isAllLanguagesItemType = args.downloadLanguageItemStatePreference.type ==
-                            DownloadLanguageItemTypePreference.AllLanguages,
                         onSavingModeStateChange = { checkBoxEnabled = it },
                         onConfirmDownload = {
                             requireContext().settings().ignoreTranslationsDataSaverWarning =

app/src/main/res/values/strings.xml

@@ -2377,6 +2377,12 @@
     <string name="translation_error_language_not_supported_learn_more">Learn more</string>
     <!-- Snackbar title shown if the user closes the Translation Request dialogue and a translation is in progress. -->
     <string name="translation_in_progress_snackbar">Translating…</string>
+    <!-- Title for the data saving mode warning dialog used in the translation request dialog.
+    This dialog will be presented when the user attempts to perform
+    a translation without the necessary language files downloaded first when Android's data saver mode is enabled and the user is not using WiFi.
+    The first parameter is the size in kilobytes or megabytes of the language file. -->
+    <string name="translations_download_language_file_dialog_title">Download language in data saving mode (%1$s)?</string>
+
 
     <!-- Translations options dialog -->
     <!-- Title of the translation options dialog that allows a user to set their translation options for the site the user is currently on. -->

app/src/test/java/org/mozilla/fenix/translations/TranslationsDialogBindingTest.kt

@@ -11,6 +11,7 @@ import mozilla.components.browser.state.state.createTab
 import mozilla.components.browser.state.store.BrowserStore
 import mozilla.components.concept.engine.translate.DetectedLanguages
 import mozilla.components.concept.engine.translate.Language
+import mozilla.components.concept.engine.translate.TranslationDownloadSize
 import mozilla.components.concept.engine.translate.TranslationEngineState
 import mozilla.components.concept.engine.translate.TranslationError
 import mozilla.components.concept.engine.translate.TranslationOperation
@@ -303,4 +304,49 @@ class TranslationsDialogBindingTest {
                 TranslationsDialogAction.UpdateTranslationError(fetchError),
             )
         }
+
+    @Test
+    fun `WHEN set translation download size action sent to the browserStore THEN update translation dialog store based on operation`() =
+        runTestOnMain {
+            translationsDialogStore =
+                spy(TranslationsDialogStore(TranslationsDialogState()))
+            browserStore = BrowserStore(
+                BrowserState(
+                    tabs = listOf(tab),
+                    selectedTabId = tabId,
+                ),
+            )
+
+            val binding = TranslationsDialogBinding(
+                browserStore = browserStore,
+                translationsDialogStore = translationsDialogStore,
+                sessionId = tabId,
+                getTranslatedPageTitle = { localizedFrom, localizedTo ->
+                    testContext.getString(
+                        R.string.translations_bottom_sheet_title_translation_completed,
+                        localizedFrom,
+                        localizedTo,
+                    )
+                },
+            )
+            binding.start()
+
+            val toLanguage = Language("de", "German")
+            val fromLanguage = Language("es", "Spanish")
+            val translationDownloadSize = TranslationDownloadSize(
+                fromLanguage = fromLanguage,
+                toLanguage = toLanguage,
+                size = 1000L,
+            )
+            browserStore.dispatch(
+                TranslationsAction.SetTranslationDownloadSizeAction(
+                    tabId = tab.id,
+                    translationSize = translationDownloadSize,
+                ),
+            ).joinBlocking()
+
+            verify(translationsDialogStore).dispatch(
+                TranslationsDialogAction.UpdateDownloadTranslationDownloadSize(translationDownloadSize),
+            )
+        }
 }

app/src/test/java/org/mozilla/fenix/translations/TranslationsDialogMiddlewareTest.kt

@@ -98,4 +98,35 @@ class TranslationsDialogMiddlewareTest {
                 )
             }
         }
+
+    @Test
+    fun `GIVEN translationState WHEN FetchDownloadFileSizeAction from TranslationDialogStore is called THEN call FetchTranslationDownloadSizeAction from BrowserStore`() =
+        runTest {
+            val browserStore = mockk<BrowserStore>(relaxed = true)
+            val translationsDialogMiddleware =
+                TranslationsDialogMiddleware(browserStore = browserStore, sessionId = "tab1")
+
+            val translationStore = TranslationsDialogStore(
+                initialState = TranslationsDialogState(),
+                middlewares = listOf(translationsDialogMiddleware),
+            )
+            translationStore.dispatch(
+                TranslationsDialogAction.FetchDownloadFileSizeAction(
+                    toLanguage = Language("en", "English"),
+                    fromLanguage = Language("fr", "France"),
+                ),
+            ).joinBlocking()
+
+            translationStore.waitUntilIdle()
+
+            verify {
+                browserStore.dispatch(
+                    TranslationsAction.FetchTranslationDownloadSizeAction(
+                        tabId = "tab1",
+                        fromLanguage = Language("fr", "France"),
+                        toLanguage = Language("en", "English"),
+                    ),
+                )
+            }
+        }
 }

app/src/test/java/org/mozilla/fenix/translations/TranslationsDialogReducerTest.kt

@@ -5,6 +5,7 @@
 package org.mozilla.fenix.translations
 
 import mozilla.components.concept.engine.translate.Language
+import mozilla.components.concept.engine.translate.TranslationDownloadSize
 import mozilla.components.concept.engine.translate.TranslationError
 import mozilla.components.support.test.robolectric.testContext
 import org.junit.Assert.assertEquals
@@ -226,4 +227,52 @@ class TranslationsDialogReducerTest {
             updatedState.translatedPageTitle,
         )
     }
+
+    @Test
+    fun `WHEN the reducer is called for UpdateDownloadTranslationDownloadSize THEN a new state with translationDownloadSize is returned`() {
+        val spanishLanguage = Language("es", "Spanish")
+        val englishLanguage = Language("en", "English")
+        val translationsDialogState =
+            TranslationsDialogState(initialTo = englishLanguage, initialFrom = spanishLanguage)
+        val translationDownloadSize = TranslationDownloadSize(
+            fromLanguage = spanishLanguage,
+            toLanguage = englishLanguage,
+            size = 1000L,
+        )
+        val updatedState = TranslationsDialogReducer.reduce(
+            translationsDialogState,
+            TranslationsDialogAction.UpdateDownloadTranslationDownloadSize(
+                translationDownloadSize,
+            ),
+        )
+
+        assertEquals(
+            translationDownloadSize,
+            updatedState.translationDownloadSize,
+        )
+    }
+
+    @Test
+    fun `WHEN the reducer is called for UpdateDownloadTranslationDownloadSize with a invalid object THEN a new state with translationDownloadSize null is returned`() {
+        val spanishLanguage = Language("es", "Spanish")
+        val englishLanguage = Language("en", "English")
+        val translationsDialogState =
+            TranslationsDialogState(initialTo = englishLanguage, initialFrom = spanishLanguage)
+        val translationDownloadSize = TranslationDownloadSize(
+            fromLanguage = englishLanguage,
+            toLanguage = spanishLanguage,
+            size = 0L,
+        )
+        val updatedState = TranslationsDialogReducer.reduce(
+            translationsDialogState,
+            TranslationsDialogAction.UpdateDownloadTranslationDownloadSize(
+                translationDownloadSize,
+            ),
+        )
+
+        assertEquals(
+            null,
+            updatedState.translationDownloadSize,
+        )
+    }
 }