Fixes 9002 error caused by test fragment risk reset (related to EXPOSUREAPP-1851) (#1037)

* Resetting the preferences deletes our database encryption credentials, but we don't delete the database itself.
On app restart, there is a mismatch between the newly generated credentials and the old database.

* Include dependency 'androidx.annotation'.
The previous commit accidentally used the transitive dependency from google-utils.

Co-authored-by: Matthias Urhahn <matthias.urhahn@sap.com>
Co-authored-by: Jakob Möller <jakob.moeller@sap.com>
Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>

Corona-Warn-App/build.gradle

@@ -235,6 +235,7 @@ dependencies {
     implementation 'androidx.preference:preference:1.1.1'
     implementation 'androidx.work:work-runtime-ktx:2.3.4'
     implementation 'android.arch.lifecycle:extensions:1.1.1'
+    implementation 'androidx.annotation:annotation:1.1.0'
 
     // QR
     implementation('com.journeyapps:zxing-android-embedded:4.1.0') { transitive = false }

Corona-Warn-App/src/deviceForTesters/java/de.rki.coronawarnapp/TestRiskLevelCalculation.kt

@@ -107,10 +107,10 @@ class TestRiskLevelCalculation : Fragment() {
             tracingViewModel.viewModelScope.launch {
                 withContext(Dispatchers.IO) {
                     try {
-                        // Database Reset
-                        AppDatabase.getInstance(requireContext()).clearAllTables()
-                        // Delete Database Instance
+                        // Preference reset
                         SecurityHelper.resetSharedPrefs()
+                        // Database Reset
+                        AppDatabase.reset(requireContext())
                         // Export File Reset
                         FileStorageHelper.getAllFilesInKeyExportDirectory().forEach { it.delete() }
 
@@ -124,7 +124,7 @@ class TestRiskLevelCalculation : Fragment() {
                 }
                 RiskLevelTransaction.start()
                 Toast.makeText(
-                    requireContext(), "Resetted, please fetch diagnosis keys from server again",
+                    requireContext(), "Reset done, please fetch diagnosis keys from server again",
                     Toast.LENGTH_SHORT
                 ).show()
             }

Corona-Warn-App/src/main/java/de/rki/coronawarnapp/storage/AppDatabase.kt

@@ -2,6 +2,7 @@ package de.rki.coronawarnapp.storage
 
 import android.content.Context
 import android.database.sqlite.SQLiteDatabase
+import androidx.annotation.VisibleForTesting
 import androidx.room.Database
 import androidx.room.Room
 import androidx.room.RoomDatabase
@@ -39,6 +40,7 @@ abstract class AppDatabase : RoomDatabase() {
             }
         }
 
+        @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
         fun resetInstance() = synchronized(this) {
             instance = null
         }