Room migration testing MigrationTestHelper version

Issue

Well, i am trying to test my database migration. Unfortunatly something looks like wrong.

@RunWith(AndroidJUnit4ClassRunner.class)
public class MigrationTest {
    private static final String TEST_DB = "migration-test";

    @Rule
    public MigrationTestHelper helper;

    public MigrationTest() {
        helper = new MigrationTestHelper(InstrumentationRegistry.getInstrumentation(),
                AppDatabase.class.getCanonicalName(),
                new FrameworkSQLiteOpenHelperFactory());
    }

    @Test
    public void migrateAll() throws IOException {
        // Create earliest version of the database.
        SupportSQLiteDatabase db = helper.createDatabase(TEST_DB, 1);
        db.close();

        // Open latest version of the database. Room will validate the schema
        // once all migrations execute.
        AppDatabase appDb = Room.databaseBuilder(
                InstrumentationRegistry.getInstrumentation().getTargetContext(),
                AppDatabase.class,
                TEST_DB)
                .addMigrations(ALL_MIGRATIONS).build();
        appDb.getOpenHelper().getWritableDatabase();
        appDb.close();
    }

    // Array of all migrations
    private static final Migration[] ALL_MIGRATIONS = new Migration[]{MIGRATION_1_2};

}

Migration code.

public static final Migration MIGRATION_1_2 = new Migration(1, 2) {
        @Override
        public void migrate(SupportSQLiteDatabase database) {
            database.execSQL("ALTER TABLE mytable ADD COLUMN reference_code TEXT");

        }
    };

All is working fine with real migration but in junit test case i have the following error.

E/SQLiteLog: (1) duplicate column name: reference_code
E/TestRunner: failed: migrateAll(com.apps.MigrationTest)
E/TestRunner: ----- begin exception -----
E/TestRunner: android.database.sqlite.SQLiteException: duplicate column name: reference_code (code 1 SQLITE_ERROR): , while compiling: ALTER TABLE mytable ADD COLUMN reference_code TEXT
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:986)
        at a

As i understand, it looks like SupportSQLiteDatabase db = helper.createDatabase(TEST_DB, 1); is creating the schema V2 of my database (and not the version 1). As a result the new column is taggued as duplicate.

To fix it i have to rollback my version = 1 to @Database class and then start my junit test again.

Can anyone help me on it ?

I follow the google guide here : https://developer.android.com/training/data-storage/room/migrating-db-versions.html

Solution

Well, i finally found it. It looks like a wrong schema has been generated in my assets folder.

To fix the issue, here is what i did.

1. Delete 1.json and 2.json files from the assets folder (each file contains the structure of the database version)
2. Rollback to the version 1 database (in my code), build > make projet
3. You will see the 1.json in your assets folder
4. Made my changes, i mean adding my new column in my Table.java file
5. Build > make projet
6. You will see the 2.json in your assets folder
7. Run the junit test, working now

Here is the difference bewteen my java object and database version 1 et 2

@Entity(tableName = "Table")
public class Table implements Parcelable {

    @ColumnInfo(name = COLUMN_REFERENCE_CODE)
    private String referenceCode;
}

Hope this will help.

Answered By - Zhar