Do not back up APKs of test-only apps, as we can not re-install them anyway

The flag to allow installation gets filtered out after we set it:
http://aosp.opersys.com/xref/android-11.0.0_r5/xref/frameworks/base/services/core/java/com/android/server/pm/PackageInstallerService.java#544

app/src/main/java/com/stevesoltys/seedvault/restore/RestoreViewModel.kt

@@ -5,7 +5,6 @@ import android.app.backup.IBackupManager
 import android.app.backup.IRestoreObserver
 import android.app.backup.IRestoreSession
 import android.app.backup.RestoreSet
-import android.content.pm.PackageManager
 import android.os.RemoteException
 import android.os.UserHandle
 import android.util.Log
@@ -31,6 +30,7 @@ import com.stevesoltys.seedvault.restore.DisplayFragment.RESTORE_BACKUP
 import com.stevesoltys.seedvault.restore.install.ApkRestore
 import com.stevesoltys.seedvault.restore.install.InstallIntentCreator
 import com.stevesoltys.seedvault.restore.install.InstallResult
+import com.stevesoltys.seedvault.restore.install.isInstalled
 import com.stevesoltys.seedvault.settings.SettingsManager
 import com.stevesoltys.seedvault.transport.TRANSPORT_ID
 import com.stevesoltys.seedvault.transport.restore.RestoreCoordinator
@@ -244,12 +244,7 @@ internal class RestoreViewModel(
             QUOTA_EXCEEDED -> FAILED_QUOTA_EXCEEDED
             UNKNOWN_ERROR -> FAILED
             APK_AND_DATA -> {
-                try {
+                if (app.packageManager.isInstalled(packageName)) FAILED else FAILED_NOT_INSTALLED
-                    app.packageManager.getPackageInfo(packageName, 0)
-                    FAILED
-                } catch (e: PackageManager.NameNotFoundException) {
-                    FAILED_NOT_INSTALLED
-                }
             }
         }
     }

app/src/main/java/com/stevesoltys/seedvault/restore/install/ApkInstaller.kt

@@ -108,7 +108,6 @@ internal class ApkInstaller(private val context: Context) {
         }
 
         // update status and offer result
-        // TODO maybe don't back up statusMsg=INSTALL_FAILED_TEST_ONLY apps in the first place?
         val status = if (success) SUCCEEDED else FAILED
         return installResult.update(packageName) { it.copy(state = status) }
     }

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

@@ -53,6 +53,13 @@ class ApkBackup(
         // do not back up when setting is not enabled
         if (!settingsManager.backupApks()) return null
 
+        // do not back up test-only apps as we can't re-install them anyway
+        // see: https://commonsware.com/blog/2017/10/31/android-studio-3p0-flag-test-only.html
+        if (packageInfo.isTestOnly()) {
+            Log.d(TAG, "Package $packageName is test-only app. Not backing it up.")
+            return null
+        }
+
         // do not back up system apps that haven't been updated
         if (packageInfo.isNotUpdatedSystemApp()) {
             Log.d(TAG, "Package $packageName is vanilla system app. Not backing it up.")

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

@@ -5,6 +5,7 @@ import android.content.Context
 import android.content.pm.ApplicationInfo.FLAG_ALLOW_BACKUP
 import android.content.pm.ApplicationInfo.FLAG_STOPPED
 import android.content.pm.ApplicationInfo.FLAG_SYSTEM
+import android.content.pm.ApplicationInfo.FLAG_TEST_ONLY
 import android.content.pm.ApplicationInfo.FLAG_UPDATED_SYSTEM_APP
 import android.content.pm.PackageInfo
 import android.content.pm.PackageManager
@@ -162,3 +163,8 @@ internal fun PackageInfo.isStopped(): Boolean {
     if (packageName == MAGIC_PACKAGE_MANAGER || applicationInfo == null) return false
     return applicationInfo.flags and FLAG_STOPPED != 0
 }
+
+internal fun PackageInfo.isTestOnly(): Boolean {
+    if (packageName == MAGIC_PACKAGE_MANAGER || applicationInfo == null) return false
+    return applicationInfo.flags and FLAG_TEST_ONLY != 0
+}

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

@@ -1,6 +1,7 @@
 package com.stevesoltys.seedvault.transport.backup
 
 import android.content.pm.ApplicationInfo.FLAG_SYSTEM
+import android.content.pm.ApplicationInfo.FLAG_TEST_ONLY
 import android.content.pm.ApplicationInfo.FLAG_UPDATED_SYSTEM_APP
 import android.content.pm.InstallSourceInfo
 import android.content.pm.PackageInfo
@@ -65,6 +66,15 @@ internal class ApkBackupTest : BackupTest() {
         assertNull(apkBackup.backupApkIfNecessary(packageInfo, UNKNOWN_ERROR, streamGetter))
     }
 
+    @Test
+    fun `does not back up test-only apps`() = runBlocking {
+        packageInfo.applicationInfo.flags = FLAG_TEST_ONLY
+
+        every { settingsManager.backupApks() } returns true
+
+        assertNull(apkBackup.backupApkIfNecessary(packageInfo, UNKNOWN_ERROR, streamGetter))
+    }
+
     @Test
     fun `does not back up system apps`() = runBlocking {
         packageInfo.applicationInfo.flags = FLAG_SYSTEM