I am currently trying to write unit tests for a project in C# that relies heavily on EntityFrameworkCore. In order to do that I have decided to use a SQLite in-memory database, and, taking inspiration from the example that can be found here, I have written the following class :

public class SqliteEFCoreContextInitializer<T> : IDisposable where T : DbContext
{

    private SQLiteConnection connection;
    private DbContextOptions<T> contextOptions;
    private Func<DbContextOptions<T>, T> contextInstantationFunction;

    // The parameter _contextInstantationFunction is there solely to get around the impossibility to directly call the context constructor from the generic type T
    public SqliteEFCoreContextInitializer(Func<DbContextOptions<T>,T> _contextInstantationFunction)
    {
        contextInstantationFunction = _contextInstantationFunction;
        connection = new SQLiteConnection("Data Source=:memory:");
        connection.Open();
        contextOptions = new DbContextOptionsBuilder<T>().UseSqlite(connection).Options;
        using T context = CreateContext();
        context.Database.EnsureCreated();
    }

    public void Dispose()
    {
        connection.Dispose();
    }

    public T CreateContext()
    {
        return contextInstantationFunction(contextOptions);
    }

}

This class is meant to be instantiated and then used like this :

// Instantiation
SqliteEFCoreContextInitializer<MyContext> sqliteContextInitializer = new(options => new MyContext(options));

//Getting the SQLite in-memory DbContext
MyContext context = sqliteContextInitializer.CreateContext();

The problem I have here is that, regardless of my database schema, I seem to always get the error “SQL logic error AUTOINCREMENT is only allowed on an INTEGER PRIMARY KEY” when executing context.Database.EnsureCreated();. After some experiments I have found out that this error is thrown even when my schema only includes a single table with no columns besides the integer primary key ! What exactly am I doing wrong here ?

Also, I don’t know whether or not this is relevant but on this project I am forced to work with the now outdated EF Core 5.0.