Question

I am using SQL Server with Entity Framework for a development of web app in .NET 4 with VS2010 RC. I would like to prepare testing database with sample data.

Should I prepare a copy of the real database (say another SQL Server database) for testing, or can I use SQLite in memory for better performance?

If using SQLite, can I use the same model EF has created for SQL Server database? How to migrate schema from SQL Server to in-memory SQLite?

How are you testing your code that uses EF with SQL Server?

Thanks for sharing.

Answer 1

I use LINQ to Objects and DI.

So let’s say I have a service which uses a repository:

public FooService : Service, IFooService
{
    private IFooRepository Repository { get; set; }

    public GetSpecialFoos()
    {
        return from f in Repository.SelectAll()
               where f.IsSpecial
               select f;
    }

    public FooService(IFooRepository repository)
    {
        this.Repository = repository;
    }
}

Now I can use constructor injection to inject a mock repository for testing. Generally, you’d use a DI framework for this. But the important thing is the mock repository can use LINQ to Objects:

public MockFooRepository : IFooRepository
{
     public IList<Foo> Data { get; set; }

     public IQueryable<Foo> SelectAll()
     {
         return Data.AsQueryable();
     }
}

Now I can test:

[TestMethod]
public void GetSpecialFoos_returns_only_special_foos()
{
    var specialId = 1;
    var notSoSpecialId = 2;
    var foos = new List<Foo> 
    {
         new Foo
         {
             Id = specialId,
             IsSpecial = true
         },
         new Foo
         {
             Id = notSoSpecialId,
             IsSpecial = false
         }
    }
    // use a DI framework here instead, in the real world
    var repository = new MockFooRepository
    {
        Data = foos
    };
    var service = new FooService(repository);

    var actual = service.GetSpecialFoos();

    var returned = actual.First();
    Assert.AreEqual(true, returned.IsSpecial);
    Assert.AreEqual(specialId, returned.Id);
}