Merge pull request #4388 from kiwix/Fixes#4387

Fixed: When changing the app's language, a blank screen appeared instead of the settings screen.

app/src/androidTest/java/org/kiwix/kiwixmobile/download/DownloadTest.kt

@@ -205,9 +205,13 @@ class DownloadTest : BaseActivityTest() {
             clickLanguagePreference(composeTestRule)
             assertLanguagePrefDialogDisplayed(composeTestRule)
             selectDeviceDefaultLanguage(composeTestRule)
+            // Advance the main clock to settle the frame of compose.
+            composeTestRule.mainClock.advanceTimeByFrame()
             clickLanguagePreference(composeTestRule)
             assertLanguagePrefDialogDisplayed(composeTestRule)
             selectAlbanianLanguage(composeTestRule)
+            // Advance the main clock to settle the frame of compose.
+            composeTestRule.mainClock.advanceTimeByFrame()
           }
         }
         clickDownloadOnBottomNav(composeTestRule)
@@ -226,6 +230,8 @@ class DownloadTest : BaseActivityTest() {
             clickLanguagePreference(composeTestRule)
             assertLanguagePrefDialogDisplayed(composeTestRule)
             selectDeviceDefaultLanguage(composeTestRule)
+            // Advance the main clock to settle the frame of compose.
+            composeTestRule.mainClock.advanceTimeByFrame()
             // check if the device default language is selected or not.
             clickLanguagePreference(composeTestRule)
             // close the language dialog.

app/src/test/java/org/kiwix/kiwixmobile/language/viewmodel/LanguageViewModelTest.kt

@@ -144,34 +144,36 @@ class LanguageViewModelTest {
   }
 
   @Test
-  fun `observeLanguages uses network when no cache and online`() = runTest {
-    every { application.getString(any()) } returns ""
-    val fetchedLanguages = listOf(language(languageCode = "eng"))
-    LanguageSessionCache.hasFetched = false
-    languages.value = emptyList()
+  fun `observeLanguages uses network when no cache and online`() = flakyTest {
+    runTest {
+      every { application.getString(any()) } returns ""
+      val fetchedLanguages = listOf(language(languageCode = "eng"))
+      LanguageSessionCache.hasFetched = false
+      languages.value = emptyList()
 
-    every { sharedPreferenceUtil.getCachedLanguageList() } returns null
-    coEvery { kiwixService.getLanguages() } returns LanguageFeed().apply {
-      entries = fetchedLanguages.map {
-        LanguageEntry().apply {
-          languageCode = it.languageCode
-          count = 1
-          title = "English"
+      every { sharedPreferenceUtil.getCachedLanguageList() } returns null
+      coEvery { kiwixService.getLanguages() } returns LanguageFeed().apply {
+        entries = fetchedLanguages.map {
+          LanguageEntry().apply {
+            languageCode = it.languageCode
+            count = 1
+            title = "English"
+          }
         }
       }
-    }
-    every { sharedPreferenceUtil.selectedOnlineContentLanguage } returns ""
-    every { sharedPreferenceUtil.saveLanguageList(any()) } just Runs
+      every { sharedPreferenceUtil.selectedOnlineContentLanguage } returns ""
+      every { sharedPreferenceUtil.saveLanguageList(any()) } just Runs
 
-    testFlow(
-      languageViewModel.actions,
-      triggerAction = {},
-      assert = {
-        val result = awaitItem()
-        assertThat(result).isInstanceOf(UpdateLanguages::class.java)
-        verify { sharedPreferenceUtil.saveLanguageList(any()) }
-      }
-    )
+      testFlow(
+        languageViewModel.actions,
+        triggerAction = {},
+        assert = {
+          val result = awaitItem()
+          assertThat(result).isInstanceOf(UpdateLanguages::class.java)
+          verify { sharedPreferenceUtil.saveLanguageList(any()) }
+        }
+      )
+    }
   }
 
   @OptIn(ExperimentalCoroutinesApi::class)

app/src/test/java/org/kiwix/kiwixmobile/zimManager/ZimManageViewModelTest.kt

@@ -314,7 +314,6 @@ class ZimManageViewModelTest {
         version = 100L
       )
       viewModel.onlineLibraryRequest.test {
-        skipItems(1)
         viewModel.updateOnlineLibraryFilters(newRequest)
         assertThat(awaitItem()).isEqualTo(newRequest)
       }

core/src/main/java/org/kiwix/kiwixmobile/core/settings/CoreSettingsFragment.kt

@@ -35,6 +35,7 @@ import android.widget.Toast
 import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.withFrameNanos
 import androidx.compose.ui.platform.ComposeView
 import androidx.compose.ui.viewinterop.AndroidView
 import androidx.core.content.ContextCompat
@@ -183,12 +184,27 @@ abstract class CoreSettingsFragment : SettingsContract.View, BaseFragment() {
     composeView = it
   }
 
+  /**
+   * Restarts the Settings screen by popping it from the back stack and reopening it.
+   *
+   * This is useful when we need to refresh the Settings UI (e.g., after a app's language
+   * change) without fully recreating the activity.
+   *
+   * Steps:
+   * 1. Get the CoreMainActivity reference to access the NavController.
+   * 2. Pop the Settings fragment from the navigation back stack.
+   * 3. Wait for one frame so the back stack can settle after the pop operation.
+   * 4. Navigate back to the Settings fragment route.
+   */
   private fun restartActivity() {
-    (activity as CoreMainActivity?)?.let {
-      it.navController.apply {
-        popBackStack()
-        navigate(it.settingsFragmentRoute)
-      }
+    val coreMainActivity = activity as? CoreMainActivity ?: return
+    val navController = coreMainActivity.navController
+    navController.popBackStack()
+    coreMainActivity.uiCoroutineScope.launch {
+      // Wait for one frame to ensure the back stack has settled before navigation
+      // Bug fix #4387
+      withFrameNanos { }
+      navController.navigate(coreMainActivity.settingsFragmentRoute)
     }
   }
 

core/src/main/java/org/kiwix/kiwixmobile/core/ui/components/KiwixAppBar.kt

@@ -29,7 +29,6 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.only
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.statusBars
-import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.MoreVert
 import androidx.compose.material3.DropdownMenu
@@ -44,21 +43,16 @@ import androidx.compose.material3.TopAppBar
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.material3.TopAppBarScrollBehavior
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.rememberUpdatedState
 import androidx.compose.runtime.setValue
-import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.style.TextOverflow
-import org.kiwix.kiwixmobile.core.downloader.downloadManager.ZERO
 import org.kiwix.kiwixmobile.core.ui.models.ActionMenuItem
 import org.kiwix.kiwixmobile.core.ui.models.toPainter
 import org.kiwix.kiwixmobile.core.ui.theme.Black
@@ -234,23 +228,3 @@ private fun OverflowMenuItems(
     }
   }
 }
-
-@Composable
-fun rememberBottomNavigationVisibility(lazyListState: LazyListState?): Boolean {
-  var isToolbarVisible by remember { mutableStateOf(true) }
-  var lastScrollIndex by remember { mutableIntStateOf(ZERO) }
-  val updatedLazyListState = rememberUpdatedState(lazyListState)
-
-  LaunchedEffect(updatedLazyListState) {
-    updatedLazyListState.value?.let { state ->
-      snapshotFlow { state.firstVisibleItemIndex }
-        .collect { newScrollIndex ->
-          if (newScrollIndex != lastScrollIndex) {
-            isToolbarVisible = newScrollIndex < lastScrollIndex
-            lastScrollIndex = newScrollIndex
-          }
-        }
-    }
-  }
-  return isToolbarVisible
-}

custom/src/test/java/org/kiwix/kiwixmobile/custom/download/CustomDownloadViewModelTest.kt

@@ -215,7 +215,6 @@ internal class CustomDownloadViewModelTest {
         triggerAction = { customDownloadViewModel.actions.tryEmit(action) },
         assert = {
           val items = (1..awaitItemCount).map { awaitItem() }
-          print("items = $items")
           assertThat(items).contains(endState)
         }
       )