Is there an in-memory provider for Entity Framework?

Question

I am unit testing code written against the ADO .NET Entity Framework. I would like to populate an in-memory database with rows, and make sure that my code retrieves them pro

Answer 1

In EF Core there are two main options for doing this:

1. SQLite in-memory mode allows you to write efficient tests against a provider that behaves like a relational database.
2. The InMemory provider is a lightweight provider that has minimal dependencies, but does not always behave like a relational database

I am using SQLite and it supports all queries, that I need to do with Azure SQL production database.

Answer 2

You could try SQL Server Compact but it has some quite wild limitations:

• SQL Server Compact does not support SKIP expressions in paging queries when it is used with the Entity Framework
• SQL Server Compact does not support entities with server-generated keys or values when it is used with the Entity Framework
• No outer joins, collate, modulo on floats, aggregates

Answer 3

Yes, there is at least one such provider - SQLite. I have used it a bit and it works. Also you can try SQL Server Compact. It's an embeded database and has EF providers too.
Edit:
SQLite has support for in-memory databases (link1). All you need is to specify a connection string like: "Data Source=:memory:;Version=3;New=True;". If you need in an example you may look at SharpArchitecture.

Answer 4

I am not familiar with Entity Framework and the ObjectQuery class but if the Include method is virtual you can mock it like this:

// Arrange
var customerSourceStub = MockRepository.GenerateStub<ObjectQuery<Customer>>();
var customers = new Customer[] 
{
    // Populate your customers as if they were coming from DB
};
customerSourceStub
    .Stub(x => x.Include("Order"))
    .Return(customers);
var sut = new CustomerService(customerSourceStub);

// Act
var actual = sut.GetCustomerById(5);

// Assert
Assert.IsNotNull(actual);
Assert.AreEqual(5, actual.Id);

Answer 5

There is not currently a in memory provider for EF, but if you take a look at Highway.Data it has a base abstraction interface and an InMemoryDataContext.

Testing Data Access and EF with Highway.Data

Answer 6

An InMemory provider is included in EF7 (pre-release).

You can use either the NuGet package, or read about it in the EF repo on GitHub (view source).