Entity Framework Test Database Initialiser

AssemblyContext.cs

using Codeant.Samples.EntityFramework;
using Machine.Specifications;

namespace Codeant.Samples.Specs
{
    public class AssemblyContext : IAssemblyContext
    {
        #region Implementation of IAssemblyContext

        public void OnAssemblyStart()
        {
            TestDatabaseInitializerUtil.Initialize();
        }

        public void OnAssemblyComplete()
        {
            //Teardown is performed as part of OnAssemblyStart()
        }

        #endregion
    }
}

Plumbing.cs

using System.Data.Entity;

namespace Codeant.Samples.EntityFramework
{
    public class DataContext : DbContext
    {
        public DbSet<User> Users { get; set; }
    }

    public class User
    {
        public string Username { get; set; }
    }
}

TestDatabaseInitializer.cs

using System;
using System.Data.Entity;

namespace Codeant.Samples.EntityFramework
{
  public class TestDatabaseInitializer<TContext> 
      : IDatabaseInitializer<TContext> where TContext : DbContext
  {
    public TestDatabaseInitializer(Action<TContext> seed = null)
    {
      Seed = seed ?? delegate { };
    }
        
    public void InitializeDatabase(TContext context)
    {
      if (context.Database.Exists())
      {
        //If the data model and database schema match
        if (context.Database.CompatibleWithModel(false))
        {

          //To speed things up no need to drop the database 
          context.Database.ExecuteSqlCommand(Sql.DisableConstraints);
          context.Database.ExecuteSqlCommand(Sql.DeleteData);
          context.Database.ExecuteSqlCommand(Sql.EnableConstraints);
          context.Database.ExecuteSqlCommand(Sql.ReseedIdentities);

        }
        else //if the data model and database do NOT match
        {

         var databaseName = context.Database.Connection.Database;

         //To close open connections set database to single user
         //Thanks to http://stackoverflow.com/a/10745559
          context.Database.ExecuteSqlCommand(
          String.Format(Sql.SetDatabaseSingleUser, databaseName));

          //Drop database
          context.Database.ExecuteSqlCommand(
          String.Format(Sql.DropDatabase, databaseName));

          context.Database.Delete();

        }
      } //END if (context.Database.Exists())

      //Create db if required
      context.Database.CreateIfNotExists();

      //Seed test data if any
      Seed(context);
    }

    public Action<TContext> Seed { get; set; }

  }

  /// <summary>
  /// Store of reusable sql statements
  /// </summary>
  public static class Sql
  {
    public const string DisableConstraints =
    "EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT all'";

    public const string DeleteData =
    "EXEC sp_MSForEachTable 'DELETE FROM ?'";

    public const string EnableConstraints =
    "EXEC sp_MSForEachTable 'ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all'";

    public const string ReseedIdentities =
    "EXEC sp_MSForEachTable 'IF OBJECTPROPERTY(object_id(''?''), ''TableHasIdentity'') = 1 DBCC CHECKIDENT (''?'', RESEED, 0) '";

    public const string SetDatabaseSingleUser =
    "ALTER DATABASE {0} SET SINGLE_USER WITH ROLLBACK IMMEDIATE";

    public const string DropDatabase =
    "USE master DROP DATABASE {0}";
  }
}

TestDatabaseInitializerUtil.cs

using System.Data.Entity;

namespace Codeant.Samples.EntityFramework
{
    /// <summary>
    /// Utility for initialising the test database
    /// </summary>
    public class TestDatabaseInitializerUtil
    {
        /// <summary>
        /// Initialises the test database with test data.
        /// </summary>
        public static void Initialize()
        {
            //Replace DataContext with your implementation
            Database.SetInitializer(
                new TestDatabaseInitializer<DataContext>(Seed));

            var context = new DataContext();
            context.Database.Initialize(false);
        }

        /// <summary>
        /// Seeds the test data.
        /// </summary>
        /// <param name="context">The context.</param>
        internal static void Seed(DataContext context)
        {
            var testUser = new User { Username = "Test" };
            context.Users.Add(testUser);

            context.SaveChanges();
        }
    }
}