This document provides clarification and practical ideas around unit testing. It begins by defining a unit test and the typical Arrange, Act, Assert structure. It then clarifies when tests are written, who writes different types of tests, and characteristics of good tests. Five practical ideas are presented to address common situations like bugs due to untested code, slow/unpredictable tests, and lack of test automation. The overall message is that unit tests form the "immune system" of a product and can replace manual testing and debugging when used properly.

1. Unit Testing From The Trenches
Alexandru Bolboaca
V1.0, because I embrace change

2. I write tests because I don't want this to happen

3. ...and I don't want to be this guy

4. Agenda
Some clarifications
5 practical ideas
Answers to your questions

5. Clarification #1: What is a unit test?
A piece of code that checks a unit from
the system under test (SUT)
A unit = a class (basic)
A unit = a behavior (advanced)

6. A unit test
Arrange Given
Act When
Assert Then

7. Clarification #2: Types of tests

8. Clarification #3: When we write tests
Design, Code, Test = Test After
Design, Test, Code = Test First
Programming
Test, Code, Design = Test Driven
Development

9. Clarification #4: Who writes the tests
Technology-facing tests: Devs
Business facing tests: Analysts and Devs
Critique tests: Testers and Devs

10. Clarification #5: Good unit tests
Simple
Fast
Readable
Independent
Repeatable
Easy to run

11. Clarification #6: Write tests for any tech
… including bash scripting

12. Anything else to clarify?

13. 5 Practical Ideas

14. Situation #1
Cost: 12 hrs of business
Cause: “a time calculation that was
incorrect for the leap year”

15. Practical Idea #1
The immune system of your product

16. Situation #2
Large proportion of tests that are:
Slow
Unpredictable

17. Practical Idea #2

18. Situation #3
I measure the development time
I want the unit test coverage to be 90%

19. Practical Idea #3
Managers measure Running Tested
Features
Developers measure coverage
Guideline: Coverage must increase

20. Situation #4
We have unit tests, BUT:
We extensively use the debugger
Unit tests are based on test plans
Testers still execute repeatedly manual
test plans

21. Practical Idea #4
Use automated developer tests to:
Executable Specifications
Replace debugging
Complement learning
Replace repetitive manual testing

22. Situation #5

23. Practical Idea #5

24. Wrap up
I measure RTF/sprint

25. Alexandru Bolboaca
alex.bolboaca@mozaicworks.com
@alexboly, alexbolboaca.ro
● Trainings: Unit Testing,
TDD, Legacy Code
● Technical Mentoring,
Coaching, on-site
and remote

26. Questions
The important thing is not to stop questioning