Always start a new RestoreSet when initializing the device

This avoids deleting the current backup when the user disables backups (or the system decides to do a random re-init).

app/src/main/java/com/stevesoltys/seedvault/transport/backup/BackupCoordinator.kt

@@ -88,13 +88,16 @@ internal class BackupCoordinator(
      * Starts a new [RestoreSet] with a new token (the current unix epoch in milliseconds).
      * Call this at least once before calling [initializeDevice]
      * which must be called after this method to properly initialize the backup transport.
+     *
+     * @return the token of the new [RestoreSet].
      */
     @Throws(IOException::class)
-    suspend fun startNewRestoreSet() {
+    private suspend fun startNewRestoreSet(): Long {
         val token = clock.time()
         Log.i(TAG, "Starting new RestoreSet with token $token...")
         settingsManager.setNewToken(token)
         plugin.startNewRestoreSet(token)
+        return token
     }
 
     /**
@@ -116,16 +119,14 @@ internal class BackupCoordinator(
      * [TRANSPORT_ERROR] (to retry following network error or other failure).
      */
     suspend fun initializeDevice(): Int = try {
-        val token = settingsManager.getToken()
-        if (token == null) {
-            Log.i(TAG, "No RestoreSet started, initialization is no-op.")
-        } else {
-            Log.i(TAG, "Initialize Device!")
-            plugin.initializeDevice()
-            Log.d(TAG, "Resetting backup metadata for token $token...")
-            plugin.getMetadataOutputStream().use {
-                metadataManager.onDeviceInitialization(token, it)
-            }
+        // we don't respect the intended system behavior here by always starting a new [RestoreSet]
+        // instead of simply deleting the current one
+        val token = startNewRestoreSet()
+        Log.i(TAG, "Initialize Device!")
+        plugin.initializeDevice()
+        Log.d(TAG, "Resetting backup metadata for token $token...")
+        plugin.getMetadataOutputStream(token).use {
+            metadataManager.onDeviceInitialization(token, it)
         }
         // [finishBackup] will only be called when we return [TRANSPORT_OK] here
         // so we remember that we initialized successfully

app/src/main/java/com/stevesoltys/seedvault/ui/recoverycode/RecoveryCodeViewModel.kt

@@ -107,9 +107,6 @@ internal class RecoveryCodeViewModel(
             storageBackup.deleteAllSnapshots()
             storageBackup.clearCache()
             try {
-                // will also generate a new backup token for the new restore set
-                backupCoordinator.startNewRestoreSet()
-
                 // initialize the new location
                 if (backupManager.isBackupEnabled) backupManager.initializeTransportsForUser(
                     UserHandle.myUserId(),

app/src/main/java/com/stevesoltys/seedvault/ui/storage/BackupStorageViewModel.kt

@@ -38,9 +38,6 @@ internal class BackupStorageViewModel(
             storageBackup.deleteAllSnapshots()
             storageBackup.clearCache()
             try {
-                // will also generate a new backup token for the new restore set
-                backupCoordinator.startNewRestoreSet()
-
                 // initialize the new location (if backups are enabled)
                 if (backupManager.isBackupEnabled) backupManager.initializeTransportsForUser(
                     UserHandle.myUserId(),

app/src/test/java/com/stevesoltys/seedvault/transport/backup/BackupCoordinatorTest.kt

@@ -72,18 +72,9 @@ internal class BackupCoordinatorTest : BackupTest() {
         requiresNetwork = false
     )
 
-    @Test
-    fun `starting a new restore set works as expected`() = runBlocking {
-        every { clock.time() } returns token
-        every { settingsManager.setNewToken(token) } just Runs
-        coEvery { plugin.startNewRestoreSet(token) } just Runs
-
-        backup.startNewRestoreSet()
-    }
-
     @Test
     fun `device initialization succeeds and delegates to plugin`() = runBlocking {
-        every { settingsManager.getToken() } returns token
+        expectStartNewRestoreSet()
         coEvery { plugin.initializeDevice() } just Runs
         coEvery { plugin.getOutputStream(token, FILE_BACKUP_METADATA) } returns metadataOutputStream
         every { metadataManager.onDeviceInitialization(token, metadataOutputStream) } just Runs
@@ -97,21 +88,17 @@ internal class BackupCoordinatorTest : BackupTest() {
         verify { metadataOutputStream.close() }
     }
 
-    @Test
-    fun `device initialization does no-op when no token available`() = runBlocking {
-        every { settingsManager.getToken() } returns null
-        every { kv.hasState() } returns false
-        every { full.hasState() } returns false
-
-        assertEquals(TRANSPORT_OK, backup.initializeDevice())
-        assertEquals(TRANSPORT_OK, backup.finishBackup())
+    private suspend fun expectStartNewRestoreSet() {
+        every { clock.time() } returns token
+        every { settingsManager.setNewToken(token) } just Runs
+        coEvery { plugin.startNewRestoreSet(token) } just Runs
     }
 
     @Test
     fun `error notification when device initialization fails`() = runBlocking {
         val maybeTrue = Random.nextBoolean()
 
-        every { settingsManager.getToken() } returns token
+        expectStartNewRestoreSet()
         coEvery { plugin.initializeDevice() } throws IOException()
         every { metadataManager.requiresInit } returns maybeTrue
         every { settingsManager.canDoBackupNow() } returns !maybeTrue
@@ -130,7 +117,7 @@ internal class BackupCoordinatorTest : BackupTest() {
     @Test
     fun `no error notification when device initialization fails when no backup possible`() =
         runBlocking {
-            every { settingsManager.getToken() } returns token
+            expectStartNewRestoreSet()
             coEvery { plugin.initializeDevice() } throws IOException()
             every { metadataManager.requiresInit } returns false
             every { settingsManager.canDoBackupNow() } returns false