NUnit Rollback After Test

I am pretty new to NUnit (and automated testing in general). I have recently done some Ruby On Rails work and noticed that in my test suite, when I create objects (such as a new user) and commit them during course of the开发者_JAVA百科 suite, they are never committed to the database so that I can run the test over and over and not worry about that user already existing.

I am now trying to accomplish the same thing in NUnit, but I am not quite sure how to go about doing it. Do I create a transaction in the Setup and Teardown blocks? Thanks.

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Why would you talk to the database during unit-tests? This makes your unit-test to integration-tests by default. Instead, create wrappers for all database communication, and stub/mock it during unit-tests. Then you don't have to worry about database state before and after.

Now, if you are not willing to that level of refactoring: The problem with transactions is that you need an open connection. So, if your method targeted for testing handles all communication on its own, it is really difficult to inject a transaction that you can create at setup and roll back at teardown.

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Maybe you can use this. It is ugly, but perhaps it can work for you:

namespace SqlServerHandling
{
[TestFixture]
public sealed class TestTransactionRollBacks
{

    private string _connectionString = "Data Source = XXXDB; ; Initial Catalog = XXX; User Id = BLABLA; Password = BLABLA";
    private SqlConnection _connection;
    private SqlTransaction _transaction; 


    [SetUp]
    public void SetUp()
    {
        _connection = new SqlConnection(_connectionString);
        _transaction = _connection.BeginTransaction();
    }

    [TearDown]
    public void TearDown()
    {
       _transaction.Rollback();
    }


    [Test]
    public void Test()
    {
        Foo foo = new Foo(_connection);

        object foo.Bar();



    }


}

internal class Foo
{
    private readonly SqlConnection _connection;
    object someObject = new object();
    public Foo(SqlConnection connection)
    {
        _connection = connection;
    }

    public object Bar()
    {
        //Do your Stuff
        return someObject;
    }
} 

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I agree with Morten's answer, but you might want to look at this very old MSDN Magazine article on the subject: Know Thy Code: Simplify Data Layer Unit Testing using Enterprise Services

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I use SQLite for unit tests, using NHibenate. Even if you're not using NHibernate it should be possible to do. SQLite has an in memory mode, where you can create a database in memory and persist data there. It is fast, works well, and you can simply throw away and recreate the schema for each test or fixture as you see fit.

You can see the example from Ayende's blog for an overview of how its done. He is using NHibernate, but the concept should work with other ORM or a straight DAL as well.