Entity Framework Integration tests DropCreateDatabaseAlways not clearing database between test

Question

I am writing a set of integration tests (Unit tests with MS Test which test that Entity Framework 4.2 is persisting all classes correctly to the database).

When I run all tests one by one they all work fine. When I run them in a group - some of them fail as the wrong number of objects are returned - it would seem that the db is being cleaned down once at the start of the tests and not in between each test - even though I can see a new context being created and then disposed of for each test

Any Ideas?

public class EmptyDataInitializer : DropCreateDatabaseAlways<myContext>
{
    protected override void Seed(myContext db)
    {
        //Do Nothing Create Empty Database
        db.SaveChanges();
        base.Seed(db);
    }
}

A Cut down version of the unit/integration Tests

[TestClass]
public class PersistanceTests
{
    //Creating two instances of our Repository so that we can make sure that we are reading from our database rather than in-memory
    private myContext _db;
    private myContext _dbResults;
    private readonly ISettings _configSettings;

    public PersistanceTests()
    {
        _configSettings = MockRepository.GenerateStub<ISettings>();
        _configSettings.ConnectionString = "data source=.;initial catalog=myContext_Test; Integrated Security=SSPI; Pooling=false";

        Database.SetInitializer(new EmptyDataInitializer());
    }

    //This is called a single time after the last test has finished executing
    [TestCleanup]
    public void TearDownTest()
    {
       _db.Dispose();
        _db = null;
       _dbResults.Dispose();
        _dbResults = null;
    }

    //This is called each time prior to a test being run

    [TestInitialize]
    public void SetupTest()
    {          
        _db = new myContext(_configSettings);
        _dbResults = new myContext(_configSettings);

        // This forces the database to initialise at this point with the initialization data / Empty DB
        var count = _db.Accounts.Count();
        var resultCount = _dbResults.Accounts.Count();
        if (count != resultCount) throw new InvalidOperationException("We do not have a consistant DB experiance.");
    }
    [TestMethod]
    public void OrganisationPersistanceTest()
    {
        // Arrange
        var apple = new Organisation { Name = "Apple" };
        _db.Organisations.Add(apple);
        // Act
        _db.SaveChanges();
        var organisationsCount = _dbResults.Organisations.Count();
        var organisationsAppleCount = _dbResults.Organisations.Where(a => a.Id == apple.Id).Count();
        var result = _dbResults.Organisations.FirstOrDefault(a => a.Id == apple.Id);
        // Assert
        Assert.IsTrue(organisationsCount == 1, string.Format("Organisations Count Mismatch -  Actual={0}, Expected={1}", organisationsCount, 1));
        Assert.IsTrue(organisationsAppleCount == 1, string.Format("Apple Organisations Count Mismatch -  Actual={0}, Expected={1}", organisationsAppleCount, 1));
        Assert.IsNotNull(result, "Organisations Result should not be null");
        Assert.AreEqual(result.Name, apple.Name, "Name Mismatch");
    }

    //A Unit test
    [TestMethod]
    public void OrganisationWithNumberOfPeople_PersistanceTest()
    {
        // Arrange
        var person = new Person { Firstname = "Bea" };
        var anotherPerson = new Person { Firstname = "Tapiwa" };
        var apple = new Organisation { Name = "Apple" };
        apple.AddPerson(person);
        apple.AddPerson(anotherPerson);
        _db.Organisations.Add(apple);
        // Act
        _db.SaveChanges();
        var organisationsCount = _dbResults.Organisations.Count();
        var organisationsAppleCount = _dbResults.Organisations.Where(a => a.Id == apple.Id).Count();
        var result = _dbResults.Organisations.FirstOrDefault(a => a.Id == apple.Id);
        var peopleCountInOrganisation = result.People.Count();
        // Assert
        Assert.IsTrue(organisationsCount == 1, string.Format("Organisations Count Mismatch -  Actual={0}, Expected={1}", organisationsCount, 1));
        Assert.IsTrue(organisationsAppleCount == 1, string.Format("Apple Organisations Count Mismatch -  Actual={0}, Expected={1}", organisationsAppleCount, 1));
        Assert.IsNotNull(result, "Organisations Result should not be null");
        Assert.AreEqual(result.People.Count, peopleCountInOrganisation, "People count mismatch in organisation Apple - Actual={0}, Expected={1}", peopleCountInOrganisation, 2); 
        Assert.AreEqual(result.Name, apple.Name, "Name Mismatch");
   }

}

Stepping through the tests I can see the SetupTest and TearDownTest methods being called but I it does not seem to clean down the database between tests.

Answer 1

Okay even Better answer - add a database.Initialize(force: true); into the TestInitialize method.

[TestInitialize]
public void SetupTest()
{          
    _db = new myContext(_configSettings);
    _db.Database.Initialize(force: true);
    _dbResults = new myContext(_configSettings);

    // This forces the database to initialise at this point with the initialization data / Empty DB
    var count = _db.Accounts.Count();
    var resultCount = _dbResults.Accounts.Count();
    if (count != resultCount) throw new InvalidOperationException("We do not have a consistant DB experiance.");
}

Answer 2

I use a helper for doing this kind of tasks:

public abstract class TestingHelper
{
        public static void ClearDatabase()
        {
            DatabaseContext myDbContext = new DatabaseContext();
            myDbContext.Database.Delete();
            myDbContext.Database.Create();
            //FillDatabase(lawyers); //<- OPTIONAL if you want to add rows to any type tables
        }
}

And then use it in the SetUp of your test:

[SetUp]
public void MyTests_SetUp()
{
      TestingHelper.ClearDatabase();
}