Question

since the dao layer methods will be dependent on data in the database,
in complex systems some operations will depend on lots of tables,
in this way unit test are not repeatable and independent,

i’m wondering how good TDD layers do this? thx.

Answer 1

A testing framework like DbUnit is exactly what you want. From their site:

DbUnit is a JUnit extension (also usable with Ant) targeted at database-driven projects that, among other things, puts your database into a known state between test runs. This is an excellent way to avoid the myriad of problems that can occur when one test case corrupts the database and causes subsequent tests to fail or exacerbate the damage.

DbUnit also supports a variety of RDBMS’s but I might recommend something like HSQLDB, which can be embedded into your project/tests so your unit tests aren’t dependent on being able to connect to a database somewhere in your company’s basement. 🙂 Although, on the other hand, you will be testing using a different RDBMS than you would be using in a production environment…