Effective Test Driven Database Development

Gojko Adzichttp://gojko.net

gojko@gojko.com

What we'll talk about:

Unit testing in the database− Stored procedures− Data management

Integration testing with Java/.NET − xUnit and FIT/FitNesse− Preparing and verifying data− Key considerations with ORMs

Lots of teams struggle with Database testing...

Bad tools Inherently hard to test O/R Mismatch Changes are persistent Attitude of DB Specialists

But I use an ORM tool...

You will still have integration issues Session management and caching can hide serious problems

If it does not fit, look for a better solution

Instead of fighting against database features, use them in your favour!

Run tests in a transaction

This makes them instantly repeatable and isolated.

Alternatively – clean up after, but prefer transactions.

Running integration tests inside a transaction

Often easier than you think... Make sure that everything goes

through the same DB connection Set up the testing framework so that

a transaction is started in set-up and rolled back on the end.

...Spring, Hibernate, FitNesse...

Declarative transactions, ORM controls the database...

So change the test runner and use the automation to your advantage...

!define TEST_RUNNER {test.RollbackServer} http://gojko.net/2008/01/22/spring-rollback/

...Spring, Hibernate, FitNesse...public void process() { ApplicationContext ctx = new

FileSystemXmlApplicationContext("lib/test.xml");

RollbackBean rollbackProcessingBean = (RollbackBean) ctx.getBean("rollback");

try { while ((size = FitProtocol.readSize(socketReader)) != 0) { try { rollbackProcessingBean.process(

new DocumentRunner(size)); } catch (RollbackNow rn) { print("rolling back now" + "\n"); } } } catch (Exception e) { exception(e); } }

...Spring, Hibernate, FitNesse

public class RollbackNow extends RuntimeException{ }

public class RollbackBean{ @Transactional public void process(Runnable r){ r.run(); throw new RollbackNow(); }}

If transactions are not possible...

Eg build tests or integrated web tests Preferably have a separate database

instance for each developer and one for the build server.

Or a dev, build and integration db Run these tests overnight

Count on stuff being in the database, but not the things

that you need Make tests self-sufficient. Don't count on the order of tests Prepare everything you need for the

test in the set-up. Or restore a known state (DbUnit,

custom loaders, base db)

Unit tests have to run quickly

...Or people simply will not run them

Full build is the only thing you can really trust

So have run full builds on a base DB and all the tests overnight

Reducing replication

Maybe use “create” scripts and generate “update” scripts

Generate Java/.NET wrappers for stored procs

Generate object definitions and loaders

If you use an ORM tool...

Flush on the end to make sure that DB and OO models are consistent

Have tests that commit and rehydrate objects in a different transaction to make sure that mappings are complete

DBFIT: Test Driven DB Development Made Easy

FIT+FitNesse+DB Fixtures

http://fitnesse.info/dbfithttp://sourceforge.net/projects/dbfit

Why DbFit?

Manipulate data in a relational model Provides all the plumbing

− Transaction management− Smart features based on meta-data− Parameter mapping− “wizards” for regression tests

Because it runs inside FitNesse, already integrated with a lot of other tools/libraries

Use DbFit to:

Write and execute DB Unit tests Prepare/verify Java or .NET integration tests

− .NET: Sql Server, Oracle, (DB2)− Java: Mysql, Oracle, (DB2, SQL Server, Derby)

Simple commands

Execute procedure Query Execute Insert Update

FitNesse symbols directly mapped to bind variables

Retrieve auto-generated keys and use them directly

<< and >> available in Java as well Already mapped to bind variables

Advanced features

Inspect queries, tables or procs to automatically generate test tables and regression tests

Store and compare queries Standalone mode for full control

Where next

Beers at the Crown ALT.NET community talk 31st July Agile 2008 in August Next talk about testing: Selenium 28th Sept http://gojko.net

Image credits

http://www.flickr.com/photos/seantubridy/ http://www.flickr.com/photos/aasta/ http://www.flickr.com/photos/guiniveve/