Don't hide potential timeline bugs by catching all exceptions (#2372)

* don't hide potential timeline bugs by catching all exceptions

* fix NetworkTimelineRemoteMediatorTest

* improve ifExpected function

* fix code formatting

app/src/main/java/com/keylesspalace/tusky/components/timeline/util/TimelineUtils.kt

@@ -0,0 +1,17 @@
+package com.keylesspalace.tusky.components.timeline.util
+
+import retrofit2.HttpException
+import java.io.IOException
+
+fun Throwable.isExpected() = this is IOException || this is HttpException
+
+inline fun <T> ifExpected(
+    t: Throwable,
+    cb: () -> T
+): T {
+    if (t.isExpected()) {
+        return cb()
+    } else {
+        throw t
+    }
+}

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/CachedTimelineRemoteMediator.kt

@@ -23,6 +23,7 @@ import androidx.room.withTransaction
 import com.google.gson.Gson
 import com.keylesspalace.tusky.components.timeline.Placeholder
 import com.keylesspalace.tusky.components.timeline.toEntity
+import com.keylesspalace.tusky.components.timeline.util.ifExpected
 import com.keylesspalace.tusky.db.AccountManager
 import com.keylesspalace.tusky.db.AppDatabase
 import com.keylesspalace.tusky.db.TimelineStatusEntity
@@ -109,7 +110,9 @@ class CachedTimelineRemoteMediator(
             }
             return MediatorResult.Success(endOfPaginationReached = statuses.isEmpty())
         } catch (e: Exception) {
-            return MediatorResult.Error(e)
+            return ifExpected(e) {
+                MediatorResult.Error(e)
+            }
         }
     }
 

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/CachedTimelineViewModel.kt

@@ -34,6 +34,7 @@ import com.keylesspalace.tusky.appstore.ReblogEvent
 import com.keylesspalace.tusky.components.timeline.Placeholder
 import com.keylesspalace.tusky.components.timeline.toEntity
 import com.keylesspalace.tusky.components.timeline.toViewData
+import com.keylesspalace.tusky.components.timeline.util.ifExpected
 import com.keylesspalace.tusky.db.AccountManager
 import com.keylesspalace.tusky.db.AppDatabase
 import com.keylesspalace.tusky.entity.Poll
@@ -191,10 +192,12 @@ class CachedTimelineViewModel @Inject constructor(
                     }
                 }
             } catch (e: Exception) {
+                ifExpected(e) {
                     loadMoreFailed(placeholderId, e)
                 }
             }
         }
+    }
 
     private suspend fun loadMoreFailed(placeholderId: String, e: Exception) {
         Log.w("CachedTimelineVM", "failed loading statuses", e)

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/NetworkTimelineRemoteMediator.kt

@@ -19,6 +19,7 @@ import androidx.paging.ExperimentalPagingApi
 import androidx.paging.LoadType
 import androidx.paging.PagingState
 import androidx.paging.RemoteMediator
+import com.keylesspalace.tusky.components.timeline.util.ifExpected
 import com.keylesspalace.tusky.db.AccountManager
 import com.keylesspalace.tusky.util.HttpHeaderLink
 import com.keylesspalace.tusky.util.dec
@@ -107,7 +108,9 @@ class NetworkTimelineRemoteMediator(
             viewModel.currentSource?.invalidate()
             return MediatorResult.Success(endOfPaginationReached = statuses.isEmpty())
         } catch (e: Exception) {
-            return MediatorResult.Error(e)
+            return ifExpected(e) {
+                MediatorResult.Error(e)
+            }
         }
     }
 }

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/NetworkTimelineViewModel.kt

@@ -28,6 +28,7 @@ import com.keylesspalace.tusky.appstore.EventHub
 import com.keylesspalace.tusky.appstore.FavoriteEvent
 import com.keylesspalace.tusky.appstore.PinEvent
 import com.keylesspalace.tusky.appstore.ReblogEvent
+import com.keylesspalace.tusky.components.timeline.util.ifExpected
 import com.keylesspalace.tusky.db.AccountManager
 import com.keylesspalace.tusky.entity.Poll
 import com.keylesspalace.tusky.entity.Status
@@ -43,6 +44,7 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.rx3.await
 import retrofit2.HttpException
 import retrofit2.Response
+import java.io.IOException
 import javax.inject.Inject
 
 /**
@@ -170,10 +172,12 @@ class NetworkTimelineViewModel @Inject constructor(
 
                 currentSource?.invalidate()
             } catch (e: Exception) {
+                ifExpected(e) {
                     loadMoreFailed(placeholderId, e)
                 }
             }
         }
+    }
 
     private fun loadMoreFailed(placeholderId: String, e: Exception) {
         Log.w("NetworkTimelineVM", "failed loading statuses", e)
@@ -214,6 +218,7 @@ class NetworkTimelineViewModel @Inject constructor(
         currentSource?.invalidate()
     }
 
+    @Throws(IOException::class, HttpException::class)
     suspend fun fetchStatusesForKind(
         fromId: String?,
         uptoId: String?,

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/TimelineViewModel.kt

@@ -33,6 +33,7 @@ import com.keylesspalace.tusky.appstore.PreferenceChangedEvent
 import com.keylesspalace.tusky.appstore.ReblogEvent
 import com.keylesspalace.tusky.appstore.StatusDeletedEvent
 import com.keylesspalace.tusky.appstore.UnfollowEvent
+import com.keylesspalace.tusky.components.timeline.util.ifExpected
 import com.keylesspalace.tusky.db.AccountManager
 import com.keylesspalace.tusky.entity.Filter
 import com.keylesspalace.tusky.entity.Poll
@@ -46,8 +47,6 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.rx3.asFlow
 import kotlinx.coroutines.rx3.await
-import retrofit2.HttpException
-import java.io.IOException
 
 abstract class TimelineViewModel(
     private val timelineCases: TimelineCases,
@@ -291,19 +290,6 @@ abstract class TimelineViewModel(
         }
     }
 
-    private fun isExpectedRequestException(t: Exception) = t is IOException || t is HttpException
-
-    private inline fun ifExpected(
-        t: Exception,
-        cb: () -> Unit
-    ) {
-        if (isExpectedRequestException(t)) {
-            cb()
-        } else {
-            throw t
-        }
-    }
-
     companion object {
         private const val TAG = "TimelineVM"
         internal const val LOAD_AT_ONCE = 30

app/src/test/java/com/keylesspalace/tusky/components/timeline/NetworkTimelineRemoteMediatorTest.kt

@@ -27,7 +27,7 @@ import org.junit.runner.RunWith
 import org.robolectric.annotation.Config
 import retrofit2.HttpException
 import retrofit2.Response
-import java.lang.RuntimeException
+import java.io.IOException
 
 @Config(sdk = [29])
 @RunWith(AndroidJUnit4::class)
@@ -66,7 +66,7 @@ class NetworkTimelineRemoteMediatorTest {
 
         val timelineViewModel: NetworkTimelineViewModel = mock {
             on { statusData } doReturn mutableListOf()
-            onBlocking { fetchStatusesForKind(anyOrNull(), anyOrNull(), anyOrNull()) } doThrow RuntimeException()
+            onBlocking { fetchStatusesForKind(anyOrNull(), anyOrNull(), anyOrNull()) } doThrow IOException()
         }
 
         val remoteMediator = NetworkTimelineRemoteMediator(accountManager, timelineViewModel)
@@ -74,7 +74,7 @@ class NetworkTimelineRemoteMediatorTest {
         val result = runBlocking { remoteMediator.load(LoadType.REFRESH, state()) }
 
         assertTrue(result is RemoteMediator.MediatorResult.Error)
-        assertTrue((result as RemoteMediator.MediatorResult.Error).throwable is RuntimeException)
+        assertTrue((result as RemoteMediator.MediatorResult.Error).throwable is IOException)
     }
 
     @Test