Hilo Unit Test

[SirSirAaron]

When I am running unit tests I don't want increment the hi when a session factory is created. Does anyone know a way in which to prevent this behavior? Additionally, it would be great if I could set the session factory's hi manually without touching the database. 

[Jason Meckley]

IIRC hi is created the first time the entity is requested, not when the factory is created. in a unit test this could occur at the same time. In either case the high value must be created. it's stored in the db to ensure uniqueness. without this there is a potential for duplicate keys. NH protects the dev from this. What you described is by design and not meant to be altered. NH is meant to touch a DB. if you don't want to touch a physical db use a sqlite in-memory db. they are lighting fast compared to a file DB.

[SirSirAaron]

Thanks for the super quick reply Jason. I think you may be right regarding the time at which nhibernate increments the "hi". I understand the basics of hilo generation and the necessity for a table to store the "hi" for synchronization across multiple session factories. That being said, I understand what I'm doing is contrary to its design and I'm purposefully looking for a hack or another way of approaching the problem.

At the moment I am using fluent nhibernate's persistencespecification tests for each of my domain objects which will eventually grow to hundred or so tests. Additionally, I create a new session factory for each test in an effort to achieve isolation. I have multiple developers running these tests daily and I would prefer not to increment the "hi". 

Right now I have a max_lo = 100

(2^31[size of int])/100[max_lo]/100[number of unit tests] =  214 748 

Lets say I have 50 developers running these tests 10 times a day then I'll be out of space after a year so:

(2^31-1)/100/100/50[developers]/10[number of times test run]/365 = 1.17

[Fran Knebels]

Why not have nhibernate regenerate the schema for every unit test. 

Now you've got total isolation because the entire schema is dropped after every test.

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[Alex Norcliffe]

+1, if you're reusing the database between fixture runs your tests can quickly become non-deterministic.

 

To speed things up for you, is SqlLite in-memory an option for your scenario?

[SirSirAaron]

Thank you for your suggestions! I decided to recreate the table each time as suggested. I sometimes share a DB with other developers so I decided create a unique key table with a partial uuid for each test to avoid race conditions. Here is my code if anyone is curious:

public class UnitTestableHiloIdConvention : IIdConvention

{

static UnitTestableHiloIdConvention()

{

UniqueTableIdentifier = Guid.NewGuid();

}

private static readonly Guid UniqueTableIdentifier;

public static string UniqueKeyUnitTestTableName

{

get

{

//nhibernate unique key unit test plus partial uuid (oracle has a max table name of 30 characters)

return "hibernate_uk_ut_" + UniqueTableIdentifier.ToString().Substring(0, 14).Replace('-', '_');

}

}

public void Apply(IIdentityInstance instance)

{

string tableName = AppInfo.IsInUnitTestMode

  ? UnitTestableHiloIdConvention.UniqueKeyUnitTestTableName

  : "hibernate_unique_key";

instance.GeneratedBy.HiLo(tableName, "next_hi", "100");

}

}

public class DatabaseTests

{

private void CreateHiloTable(int initialHi = 0)

{

string createQuery = String.Format("CREATE TABLE [{0}]( "

+ "[next_hi] [int] NOT NULL, "

+ "CONSTRAINT [PK_{0}] PRIMARY KEY CLUSTERED ([next_hi] ASC) "

  + ")"

  , UnitTestableHiloIdConvention.UniqueKeyUnitTestTableName);

ExecuteSqlQuery(createQuery);

string insertQuery = String.Format("INSERT INTO [{0}] VALUES({1});"

  , UnitTestableHiloIdConvention.UniqueKeyUnitTestTableName, initialHi);

ExecuteSqlQuery(insertQuery);

}

private void DeleteHiloTable()

{

//check if table exists before deleting it 

string deleteQuery = String.Format("IF OBJECT_ID('[{0}]','U') IS NOT NULL "

  + "DROP TABLE [{0}];"

  , UnitTestableHiloIdConvention.UniqueKeyUnitTestTableName);

ExecuteSqlQuery(deleteQuery);

}

private void ExecuteSqlQuery(string query)

{

using (ISession session = SessionFactory.OpenSession())

using (ITransaction transaction = session.BeginTransaction())

{

session.CreateSQLQuery(query).ExecuteUpdate();

transaction.Commit();

}

}

[SetUp]

public void SetUp()

{

CreateHiloTable();

Session = SessionFactory.OpenSession();

NHibernate.Context.CurrentSessionContext.Bind(Session);

//evict cached data

Session.Clear();

Transaction = Session.BeginTransaction();

}

[TearDown]

public void TearDown()

{

Transaction.Rollback();

Transaction.Dispose();

Session.Close();

Session.Dispose();

DeleteHiloTable();

}

}

On Friday, June 8, 2012 6:40:35 PM UTC-4, Alex Norcliffe wrote:

+1, if you're reusing the database between fixture runs your tests can quickly become non-deterministic.

 

To speed things up for you, is SqlLite in-memory an option for your scenario?

 

On 8 June 2012 23:33, Fran Knebels <fkne...@gmail.com> wrote:

Why not have nhibernate regenerate the schema for every unit test. 

Now you've got total isolation because the entire schema is dropped after every test.

On Jun 8, 2012 5:51 PM, "SirSirAaron" <theyell...@gmail.com> wrote:

Thanks for the super quick reply Jason. I think you may be right regarding the time at which nhibernate increments the "hi". I understand the basics of hilo generation and the necessity for a table to store the "hi" for synchronization across multiple session factories. That being said, I understand what I'm doing is contrary to its design and I'm purposefully looking for a hack or another way of approaching the problem.

At the moment I am using fluent nhibernate's persistencespecification tests for each of my domain objects which will eventually grow to hundred or so tests. Additionally, I create a new session factory for each test in an effort to achieve isolation. I have multiple developers running these tests daily and I would prefer not to increment the "hi". 

Right now I have a max_lo = 100

(2^31[size of int])/100[max_lo]/100[number of unit tests] =  214 748 

Lets say I have 50 developers running these tests 10 times a day then I'll be out of space after a year so:

(2^31-1)/100/100/50[developers]/10[number of times test run]/365 = 1.17

On Friday, June 8, 2012 5:02:49 PM UTC-4, Jason Meckley wrote:

IIRC hi is created the first time the entity is requested, not when the factory is created. in a unit test this could occur at the same time. In either case the high value must be created. it's stored in the db to ensure uniqueness. without this there is a potential for duplicate keys. NH protects the dev from this. What you described is by design and not meant to be altered. NH is meant to touch a DB. if you don't want to touch a physical db use a sqlite in-memory db. they are lighting fast compared to a file DB.

On Friday, June 8, 2012 3:35:11 PM UTC-4, SirSirAaron wrote:

When I am running unit tests I don't want increment the hi when a session factory is created. Does anyone know a way in which to prevent this behavior? Additionally, it would be great if I could set the session factory's hi manually without touching the database. 

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