Testing database on Android: ProviderTestCase2 or RenamingDelegatingContext?

Question

I\'ve implemented access to a database using SQLiteOpenHelper from the android.database package within some classes (with pattern DAO).

I wrote some jun

Answer 1

I actually use database with SQLiteOpenHelper and I have a trick for testing. The idea is to use standard on-file stored DB during the normal use of the app and an in-memory DB during tests. In this way you can use a clear DB for each test without insert/delete/update data in your standard DB. It works fine for me.

Keep in mind you can use in-memory database, just passing null as name of database file. This is clearly documented in the API documentation.

Advantages of using in-memory DB during tests is explained here: https://attakornw.wordpress.com/2012/02/25/using-in-memory-sqlite-database-in-android-tests/

In my project I have the DBHelper class wich extends SQLiteHelper. As you can see, there are the standard methods. I simply added a constructor with two parameters. The difference is that when I call the super constructor, I pass null as DB name.

public class DBHelper extends SQLiteOpenHelper {

    public static final int DATABASE_VERSION = 1;
    public static final String DATABASE_NAME = "mydatabase.db";

    public DBHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    public DBHelper(Context context, boolean testMode) {
        super(context, null, null, DATABASE_VERSION);
    }

    public void onCreate(SQLiteDatabase db) {
        //create statements
    }

    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        //on upgrade policy
    }

    public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        //on downgrade policy
    }
}

Every "model" in the project extends DBModel that is an abstract class.

public abstract class DBModel {
    protected DBHelper dbhelper;

    public DBModel(Context context) {
        dbhelper = new DBHelper(context);
    }

    //other declarations and utility function omitted

}

As discussed here: How can I find out if code is running inside a JUnit test or not? there is a way to establish if you are running JUnit tests, simply searching in stack trace elements. As a conseguence, I modified DBModel constructor

public abstract class DBModel {
    protected DBHelper dbhelper;

    public DBModel(Context context) {
        if(isJUnitTest()) {
            dbhelper = new DBHelper(context, true);
        } else {
            dbhelper = new DBHelper(context);
        }
    }

    private boolean isJUnitTest() {
        StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
        List list = Arrays.asList(stackTrace);
        for (StackTraceElement element : list) {
            if (element.getClassName().startsWith("junit.")) {
                return true;
            }
        }
        return false;
    }

    //other declarations and utility function omitted

}

Note that

startsWith("junit.")

may be

startsWith("org.junit.")

in your case.