Unit testing Castle Active Record using SQLite in-memory database

Sorry about the formatting and everything else but here is how I enabled SQLite in-memory mode for database hitting unit tests in Visual Studio. The approach is not ideal but it works with TestDriven.net.

The software

Download the Finisar SQLite provider. Copy the files SQLite.NET.dll and SQLite3.dll into your test project root. Add a reference to SQLite.NET.dll. Change the properties of SQLite3.dll from “Allways copy” to “If newer”.

Custom connection provider

The SQLite in-memory destroys all the data in the database when the connection is closed. By default, when using Castle Active Record the connection are closed after every operation like CreateSchema(). There can be some property setting to use the same connection for all the operations between a test setup and tear down, but it was quite easy to write a custom connector that does the same thing. Here is the code.

public class SQLiteInMemoryTestingConnectionProvider : NHibernate.Connection.DriverConnectionProvider
{
public static System.Data.IDbConnection Connection = null;

public override System.Data.IDbConnection GetConnection()
{
if (Connection == null)
Connection = base.GetConnection();

return Connection;
}

public override void CloseConnection(System.Data.IDbConnection conn) { }
}

Configuring the Active Record

Set the following properties for Active Record initialization:

hibernate.connection.driver_class = NHibernate.Driver.SQLiteDriver

hibernate.dialect = NHibernate.Dialect.SQLiteDialect

hibernate.connection.provider = MyNamespace.SQLiteInMemoryTestingConnectionProvider, MyAssemblyNameContainingTheProvider

hibernate.query.substitutions = true=1;false=0

hibernate.connection.connection_string = Data Source=:memory:;Version=3;New=True;

Closing the connection after each test

In your test tear down method, close the connection manually:

if (SQLiteInMemoryTestingConnectionProvider .Connection != null) SQLiteInMemoryTestingConnectionProvider .Connection.Close();

SQLiteInMemoryTestingConnectionProvider .Connection = null;

This causes the data created by the test to be destroyed. Use test setup to recreate the database schema for the following test.

Test-driven development in a challenging environment

I started writing my master’s thesis today. It will be a case study on a project where I will re-implement part of an existing system using test driven development. What makes it interesting is that the component to be implemented consists of a SharePoint Web Part user interface and it integrates to Microsoft Project Server. I haven’t done any .Net or SharePoint development in ages and the guys at work said that it’s quite difficult to write unit tests for that kind of stuff. Of course I didn’t believe them!

I think I’ll be making notes on interesting findings here if there will be any.

Code coverage

Full test coverage is a good goal to reach for but it does not prove your program correct.

public int multiply(int a, int b) {
  return a + b;
}

public void testMultiply() {
  assertEquals( 4, multiply(2,2) );
}

The above multiply method has full test coverage (statement, path) and it passes the test(s) but it clearly doesn’t do what it is supposed to do.