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Effective Test Driven
Database Development
Gojko Adzic
http://gojko.net
[email protected]
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/dbfit
http://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/