1. Introduction to good practices in
software development
Testing &
Continuous Delivery 101
Nelson Melina

2. What is Unit Testing ?
● An Unit is smallest testable part of source
code.
● It Can be an entire interface or just a method
(OOP).
● Unit Testing isolates parts of a software and
verify that each parts behave as intended.

3. What are the benefits of Unit Testing
?
● You will find potential problems at the earliest
time possible.
● You can refactor code without the fear or
regression issues.
● The tests serve as a design documentation
of how a unit is supposed to work.

4. What are the limits of Unit Testing ?
● They only show the presence or absence of
particular errors
● For every line of code written, programmers
often need 3 to 5 lines of test code.
● Nondeterministic and multiple threads
algorithms can not be easily tested.
● Rigorous discipline is needed throughout the
software development process.

5. What are the most common tools of
Unit Testing ?
● JUnit (framework)
● DBUnit (extension of JUnit)
● Mock objects frameworks

6. Mock Objects
● They are simulated objects that mimic the behavior of
real objects in controlled ways
● We need to use them when an object :
– returns non-deterministic results.
– has states that are difficult to reproduce (e.g., a network
error).
– is slow (e.g., a database).
– does not yet exist or may change behavior.
– would have to include information or methods only for
testing.

7. What is Integration Testing ?
● Occurs after Unit Testing and before
validation testing.
● Combination of individual software modules
that will be tested as a group.

8. The next step towards complete
efficiency is Continuous Integration

9. Repository
Unit tests A
Code A
Code B
Code C
Unit tests B
Unit tests C
Unit Tests A, B, C
& Integration Tests
(A + B + C)
Module A (Wallet)
Module B (Widget)
Module C (MAV)
Feedbacks (Alerts,
Information, Errors or
Statuses) via email to
whom is concerned.
Continuous Integration Server
(Hudson)
Is the aggregate
behaving well ?

10. Here are the key principles of CI
● Maintain a code repository.
●
Automate the build.
●
Make the build self-testing.
●
Everyone commits every day.
● Every commit should be built.
●
Keep the build fast.
●
Test in a clone of the production environment.
●
Make it easy to get the latest deliverables.
● Everyone can see the results of the latest build.
●
Automate deployment.

11. Advantages of Continuous
Integration
● When unit tests fail, developers can revert to a bug
free state.
● Integration problems and problematic changes are
continuously detected and fixed.
● Immediate feedback to developers.
● Frequent code commits pushes developers to create
modular and less complex code.
● Metrics generated from automated testing and CI.

12. The final goal is to achieve
Continuous Delivery

13. What is Continuous Delivery ?

14. Why would we change our way of
working ?
● Reduce current and future costs
– Without an automated process, developers lose a great amount
of time testing manually the features they program.
– The latter we find a bug, the more expensive it is to fix.
*
● Reduce risks
– It is impossible to guaranty that all manually executed test will
always be thorough and accurate.

15. Go further
● http://www.citconf.com/
● http://www.martinfowler.com/articles/continuousIntegration.html
● http://confluence.public.thoughtworks.org/display/CC/CI+Feature+Matrix
● http://www.thoughtworks.com/continuous-delivery
● http://www.thoughtworks-studios.com/content/introduction-continuous-delivery
● http://stackoverflow.com
● http://continuousdelivery.com/
● http://www.thoughtworks-studios.com/content/introduction-continuous-delivery
● http://programmers.stackexchange.com/questions/140156/is-unit-testing-or-test-driven-d
● http://elegantcode.com/2012/01/06/you-are-responsible-for-making-that-feature-work-wr
● http://www.scrumalliance.org/articles/486-unit-testing-ignored-and-
misunderstood