Added tests to reason about backward compatibility

Author: ashwinraghav

transport/transport-runtime/src/main/java/com/google/android/datatransport/runtime/scheduling/persistence/SchemaManager.java

@@ -142,8 +142,12 @@ private void ensureConfigured(SQLiteDatabase db) {
 
   @Override
   public void onCreate(SQLiteDatabase db) {
+    onCreate(db, schemaVersion);
+  }
+
+  private void onCreate(SQLiteDatabase db, int version) {
     ensureConfigured(db);
-    upgrade(db, 0, schemaVersion);
+    upgrade(db, 0, version);
   }
 
   @Override
@@ -159,7 +163,7 @@ public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
     db.execSQL(DROP_CONTEXTS_SQL);
     // Indices are dropped automatically when the tables are dropped
 
-    onCreate(db);
+    onCreate(db, newVersion);
   }
 
   @Override

transport/transport-runtime/src/test/java/com/google/android/datatransport/runtime/scheduling/persistence/SchemaManagerMigrationTest.java

@@ -0,0 +1,85 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.android.datatransport.runtime.scheduling.persistence;
+
+import static com.google.android.datatransport.runtime.scheduling.persistence.SchemaManager.DB_NAME;
+import static com.google.android.datatransport.runtime.scheduling.persistence.SchemaManager.SCHEMA_VERSION;
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.ContentValues;
+import android.database.sqlite.SQLiteDatabase;
+import androidx.test.core.app.ApplicationProvider;
+import com.google.android.datatransport.Encoding;
+import com.google.android.datatransport.Priority;
+import com.google.android.datatransport.runtime.EncodedPayload;
+import com.google.android.datatransport.runtime.EventInternal;
+import com.google.android.datatransport.runtime.TransportContext;
+import com.google.android.datatransport.runtime.time.TestClock;
+import com.google.android.datatransport.runtime.time.UptimeClock;
+import com.google.android.datatransport.runtime.util.PriorityMapping;
+import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Map;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.ParameterizedRobolectricTestRunner;
+import org.robolectric.RobolectricTestRunner;
+
+@RunWith(ParameterizedRobolectricTestRunner.class)
+public class SchemaManagerMigrationTest {
+    private final int toVersion;
+    private final int fromVersion;
+
+    @ParameterizedRobolectricTestRunner.Parameters(name = "lowVersion = {0}, highVersion = {1}")
+    public static Collection<Object[]> data() {
+        Collection<Object[]> params = new ArrayList<>();
+        for(int fromVersion  = 1 ; fromVersion < SCHEMA_VERSION; fromVersion ++) {
+            for (int toVersion = fromVersion + 1; toVersion <= SCHEMA_VERSION; toVersion++) {
+                params.add(new Object[]{fromVersion, toVersion});
+            }
+        }
+        return params;
+    }
+
+    public SchemaManagerMigrationTest(int fromVersion, int toVersion) {
+        this.fromVersion = fromVersion;
+        this.toVersion = toVersion;
+    }
+
+    @Test
+    public void upgrade_migratesSuccessfully() {
+        SchemaManager schemaManager =
+                new SchemaManager(ApplicationProvider.getApplicationContext(), DB_NAME, fromVersion);
+        schemaManager.onUpgrade(schemaManager.getWritableDatabase(), fromVersion, toVersion);
+    }
+
+    @Test
+    public void downgrade_migratesSuccessfully() {
+        SchemaManager schemaManager =
+                new SchemaManager(ApplicationProvider.getApplicationContext(), DB_NAME, toVersion);
+        schemaManager.onDowngrade(schemaManager.getWritableDatabase(), toVersion, fromVersion);
+    }
+
+    @Test
+    public void downgrade_upgrade_migratesSuccessfully() {
+        SchemaManager schemaManager =
+                new SchemaManager(ApplicationProvider.getApplicationContext(), DB_NAME, toVersion);
+
+        schemaManager.onDowngrade(schemaManager.getWritableDatabase(), toVersion, fromVersion);
+        schemaManager.onUpgrade(schemaManager.getWritableDatabase(), fromVersion, toVersion);
+    }
+}