TDD style proved itself as very reliable and quick way of business tasks solving with code. But most of examples on trainings and in the internet show how to apply TDD to simple input/output code or interface based dependencies with mocking techniques. What about other areas of application development like database related code? Could it be developed with TDD style? What does TDD bring to developer? I will try to answer these questions in my talk and show on practical examples how helpful TDD is for database code, how it reduces risks and opens the door for refactoring techniques.

1. TDD for DB related code
Mikalai Alimenkou
http://xpinjection.com
@xpinjection

3. Data is very important

4. What to
test, master?
Everything!

5. DB testing checklist
O/R mappings
Data flow (incoming and outgoing data)
Stored procedures, functions, triggers
Database schema
View definitions
Referential integrity
Default values for a column
Data invariants for a single column
Data invariants involving several columns
Database performance

6. Are you
crazy?

7. Lets talk about techniques

8. Small quiz: How to test DB code?
Mock direct DB access API
(JDBC in Java)
Mock high level DB access
API (ORM and data access
frameworks)
Mock DB server (SQL level)
Test on real DB

9. Simplest testing technique
Provide input
data (params +
DB state)
Invoke tested
behavior
Assert
returned value
+ DB state

10. Rollback transactions
We rollback the uncommitted test
transaction as part of the teardown.

11. Each test is a hero
Each test knows what data is needed
and prepares affected tables.

12. Constraints and validations
Test suites
Referential integrity
Domain integrity
Main suite
Integration
suite
Validation
suite
Each test may manage constraints in runtime

13. Database structure management
Incremental updates for all environments

14. Simple tools
data sets management
integration code and
regular testing DB operations
database management
and versioning

15. TDD benefits
No need to have checklists
for DB related code
Minimal amount of code
and DB changes
Full control under data access code
Open the door for DB refactoring

16. Show me the code!

17. @xpinjection
http://xpinjection.com
mikalai.alimenkou@xpinjection.com