Error ошибка drop database не может выполняться внутри блока транзакции

Not really sure if this question belongs here, but I hope someone could help me out.

I’ve made integration tests going all the way down to the database (using mssql localDB). I want each test to run independently with it’s own data — I want to reseed the database with my fake data before each test is running. I tried to implement it with transactions without success. Here is how I tried to pull it off:

public class TestDbInitializer : DropCreateAlways<MyContext>()
{
    public static List<Item> Items;

    public override Seed(DbContext context)
    {
        Items = new List<Item>();

        // Adding items
        // .. 

        Items.ForEach(x => context.Add(x));

        context.SaveChanges();
    }
}


public class BaseTransactionsTests
{
    private TransactionScope _scope

    [TestInitialize]
    public void Initialize()
    {
        _scope = new TransactionScope();
    }

    [TestCleanup]
    public void Cleanup()
    {
        _scope.Dispose();
    }
}

[TestClass]
public class IntegrationTests : BaseTransactionsTests

private IDependenciesContainer _container;

public static void AssemblyInit(TestContext context)
{
    Database.SetInitializer(new TestDbInitializer());

    _container = new DependenciesContainer();

    // Registers all my application's dependencies
    _container.RegisterAll();
}

[TestInitialize]
public void Initialize()
{
    using (var context = new MyContext("TestsDatabase"))
    {
        context.Initialize(true);
    }
}

[TestMethod]
public void TestAddItem()
{
    var controller = _container.Resolve<MyController>();

    var result = controller.AddItem(new Item({Name = "Test"}))

    var goodResult = result as OkNegotiatedResult<string>();

    if (result == null)
        Assert.Fail("Bad result")

    using (var context = new MyContext("TestsDatabase"))
    {
        Assert.AreEqual(context.Items.Count, TestDbInitializer.Items.Count + 1)
    }
}

I use my dependency injector in my tests, registering all dependencies once (AssemblyInitialize).

I created a DB instance for testings, and a specific DropCreateAlways initializer with a fake data Seed method, which I set as the initializer in the AssemblyInitialize as well.

I want to reseed the database with my fake data before each test run. For that case I implemented the base class which holds a transaction scope.

When I run my tests, the following exception is thrown when Seeding the database in the TestInitialize:

DROP DATABASE statement cannot be used inside a user transaction

How should I deal with it? Moreover, what do you think of my implementation of those integration tests? What could be improved?

Not really sure if this question belongs here, but I hope someone could help me out.

I’ve made integration tests going all the way down to the database (using mssql localDB). I want each test to run independently with it’s own data — I want to reseed the database with my fake data before each test is running. I tried to implement it with transactions without success. Here is how I tried to pull it off:

public class TestDbInitializer : DropCreateAlways<MyContext>()
{
    public static List<Item> Items;

    public override Seed(DbContext context)
    {
        Items = new List<Item>();

        // Adding items
        // .. 

        Items.ForEach(x => context.Add(x));

        context.SaveChanges();
    }
}


public class BaseTransactionsTests
{
    private TransactionScope _scope

    [TestInitialize]
    public void Initialize()
    {
        _scope = new TransactionScope();
    }

    [TestCleanup]
    public void Cleanup()
    {
        _scope.Dispose();
    }
}

[TestClass]
public class IntegrationTests : BaseTransactionsTests

private IDependenciesContainer _container;

public static void AssemblyInit(TestContext context)
{
    Database.SetInitializer(new TestDbInitializer());

    _container = new DependenciesContainer();

    // Registers all my application's dependencies
    _container.RegisterAll();
}

[TestInitialize]
public void Initialize()
{
    using (var context = new MyContext("TestsDatabase"))
    {
        context.Initialize(true);
    }
}

[TestMethod]
public void TestAddItem()
{
    var controller = _container.Resolve<MyController>();

    var result = controller.AddItem(new Item({Name = "Test"}))

    var goodResult = result as OkNegotiatedResult<string>();

    if (result == null)
        Assert.Fail("Bad result")

    using (var context = new MyContext("TestsDatabase"))
    {
        Assert.AreEqual(context.Items.Count, TestDbInitializer.Items.Count + 1)
    }
}

I use my dependency injector in my tests, registering all dependencies once (AssemblyInitialize).

I created a DB instance for testings, and a specific DropCreateAlways initializer with a fake data Seed method, which I set as the initializer in the AssemblyInitialize as well.

I want to reseed the database with my fake data before each test run. For that case I implemented the base class which holds a transaction scope.

When I run my tests, the following exception is thrown when Seeding the database in the TestInitialize:

DROP DATABASE statement cannot be used inside a user transaction

How should I deal with it? Moreover, what do you think of my implementation of those integration tests? What could be improved?

Сообщение об ошибке так же ясно, как руководство на этом:

DROP DATABASE не может выполняться внутри блока транзакции.

Функция plgpsql автоматически окружается блоком транзакции. Короче говоря, вы не можете сделать это напрямую. Есть ли особая причина, по которой вы не можете просто вызвать команду DDL?

DROP database $mydb;

Ты может обойти эти ограничения с помощью дополнительного модуля дблинк as @ Игорь предложенный. Вам нужно установить его один раз для каждой базы данных — ту, в которой вы вызываете функции dblink, а не (другую), в которой вы выполняете команды.
Позволяет написать функцию, используя dblink_exec() как это:

CREATE OR REPLACE FUNCTION f_drop_db(text)
  RETURNS text LANGUAGE sql AS
$func$
SELECT dblink_exec('port=5432 dbname=postgres'
                  ,'DROP DATABASE ' || quote_ident($1))
$func$;

quote_ident() предотвращает возможную SQL-инъекцию.

Звоните:

SELECT f_drop_db('mydb');

В случае успеха вы видите:

УДАЛИТЬ БАЗУ ДАННЫХ

Строка подключения может даже указывать на ту же базу данных, в которой работает ваш сеанс. Команда выполняется за пределами блока транзакции, что имеет два последствия:

• Его нельзя откатить назад.
• Он позволяет вам звонить DROP DATABASE «через прокси» из функции.

Вы могли бы создать FOREIGN DATA WRAPPER и FOREIGN SERVER чтобы сохранить соединение и упростить вызов:

CREATE FOREIGN DATA WRAPPER postgresql VALIDATOR postgresql_fdw_validator;

CREATE SERVER your_fdw_name_here FOREIGN DATA WRAPPER postgresql
OPTIONS (hostaddr '12.34.56.78', port '5432', dbname 'postgres');

Использование базы данных обслуживания по умолчанию postgres, что было бы очевидным выбором. Но возможна любая БД.

Упрощенная функция, использующая это:

CREATE OR REPLACE FUNCTION f_drop_db(text)
  RETURNS text LANGUAGE sql AS
$func$
SELECT dblink_exec('your_fdw_name_here', 'DROP DATABASE ' || quote_ident($1))
$func$;