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FacebookWith version 4.1 or later Entity Framework provides a useful way for recreate and optionally re-seed the database with data the first time or before the execution of unit test.
For this purpose Microsoft provides some classes:
- CreateDatabaseIfNotExists
- DropCreateDatabaseAlways
- DropCreateDatabaseIfModelChanges
All classes implement interface IDatabaseInitializer<T> where T is a DbContext.
For example if you want populate database with base informations before execute
an unit test you can write code like this:
public class MyTestIntializer : DropCreateDatabaseAlways<MyContext>
{
protected override void Seed( MyContext context )
{
var categories = new Lists<Category>();
var products = new Lists<Product>();
categories.Add( new Category { Name = "tech" } );
categories.Add( new Category { Name = "food" } );
products.Add( new Product { Name = "cpu", Category = categories[0] } );
products.Add( new Product { Name = "harddisk",
Category = categories[0] } );
products.Add( new Product { Name = "biscuits",
Category = categories[1] } );
addToContext<Category>( context, categories );
addToContext<Product>( context, products );
}
private void addToContext<T>( MyContext context, IList collection )
{
foreach( var item in collection )
{
context.Set<T>().Add( item );
}
}
}
This data initializer drop (if exists) and create database and finally populate it with
categories and products.
Now we can add it to our test class.
[ClassInitialize()]
public static void MyClassInitialize( TestContext testContext )
{
Database.SetInitializer<MyContext>( new MyTestIntializer() );
}
).
