Adding a constructor with 2 params for the MigrationTestHelper.
Bug: 63130998
Test: MigrationTest

Change-Id: Ib1d0d117df12d736e139750252a74af0860823cc
diff --git a/room/integration-tests/testapp/src/androidTest/java/android/arch/persistence/room/integration/testapp/migration/MigrationTest.java b/room/integration-tests/testapp/src/androidTest/java/android/arch/persistence/room/integration/testapp/migration/MigrationTest.java
index 6d464b5..6fb1186 100644
--- a/room/integration-tests/testapp/src/androidTest/java/android/arch/persistence/room/integration/testapp/migration/MigrationTest.java
+++ b/room/integration-tests/testapp/src/androidTest/java/android/arch/persistence/room/integration/testapp/migration/MigrationTest.java
@@ -52,7 +52,7 @@
 
     public MigrationTest() {
         helper = new MigrationTestHelper(InstrumentationRegistry.getInstrumentation(),
-                MigrationDb.class.getCanonicalName(), new FrameworkSQLiteOpenHelperFactory());
+                MigrationDb.class.getCanonicalName());
     }
 
     @Test
diff --git a/room/testing/src/main/java/android/arch/persistence/room/testing/MigrationTestHelper.java b/room/testing/src/main/java/android/arch/persistence/room/testing/MigrationTestHelper.java
index bb5a712..1c5edd0 100644
--- a/room/testing/src/main/java/android/arch/persistence/room/testing/MigrationTestHelper.java
+++ b/room/testing/src/main/java/android/arch/persistence/room/testing/MigrationTestHelper.java
@@ -19,6 +19,7 @@
 import android.app.Instrumentation;
 import android.arch.persistence.db.SupportSQLiteDatabase;
 import android.arch.persistence.db.SupportSQLiteOpenHelper;
+import android.arch.persistence.db.framework.FrameworkSQLiteOpenHelperFactory;
 import android.arch.persistence.room.DatabaseConfiguration;
 import android.arch.persistence.room.Room;
 import android.arch.persistence.room.RoomDatabase;
@@ -88,6 +89,18 @@
      * @param instrumentation The instrumentation instance.
      * @param assetsFolder    The asset folder in the assets directory.
      */
+    public MigrationTestHelper(Instrumentation instrumentation, String assetsFolder) {
+        this(instrumentation, assetsFolder, new FrameworkSQLiteOpenHelperFactory());
+    }
+
+    /**
+     * Creates a new migration helper. It uses the Instrumentation context to load the schema
+     * (falls back to the app resources) and the target context to create the database.
+     *
+     * @param instrumentation The instrumentation instance.
+     * @param assetsFolder    The asset folder in the assets directory.
+     * @param openFactory     Factory class that allows creation of {@link SupportSQLiteOpenHelper}
+     */
     public MigrationTestHelper(Instrumentation instrumentation, String assetsFolder,
             SupportSQLiteOpenHelper.Factory openFactory) {
         mInstrumentation = instrumentation;