Le slide della sessione che ho tenuto agli Italian Agile Days del 2016, Pavia, 18-19 Novembre

1. Ferdinando
Santacroce
@JesusWasRasta
TDD a piccoli passi

2. All’inizio le mie applicazioni
le testavo così...

3. Vediamo un po’ come funziona...

4. mmm, pensavo fosse
meno complicato...

5. Ho capito,
devo usare i mock!

6. Sì, ma che fatica!

7. Driven!!

8. Cos’è TDD?
Scrivi dei test
Scrivi codice fino a
farli passare tutti
Fai un po’ di pulizia

9. The Three Laws of TDD
1. “You aren’t allowed to write any production code
until you have written a failing unit test”.
2. “You aren’t allowed to write more of a unit test
than is sufficient to fail. And not compiling is
failing.”
3. “You aren’t allowed to write more production code
than is sufficient to pass the currently failing unit
test.”

10. Ecco cos’è TDD!
Write a single test
that fails
Write code to
make the test pass
Improve the code base

11. The Three Laws of TDD
1. “You aren’t allowed to write any production code until you have
written a failing unit test”.
2.“You aren’t allowed to write more of a unit test than is sufficient
to fail. And not compiling is failing.”
3. “You aren’t allowed to write more
production code than is sufficient to pass
the currently failing unit test.”

12. Proviamoci!
See the code on Github:
https://github.com/jesuswasrasta/SmallStepsTDD.git

13. • Nell’algoritmo non v’è espresso il concetto di numero primo
• Brainlessness (2 -> n)
• I cicli sono una generalizzazione delle if
• Passo dei test nuovi senza modificare codice
• Se immaginiamo i test come feature, che bello sarebbe aggiungere
funzionalità al nostro software con questa facilità?!
• Refactoring: rimuovere duplicazione, rimuovere codice
Cosa si nota?

14. ({}–>nil) no code at all->code that employs nil
(nil->constant)
(constant->constant+) a simple constant to a more complex constant
(constant->scalar) replacing a constant with a variable or an argument
(statement->statements) adding more unconditional statements.
(unconditional->if) splitting the execution path
(scalar->array)
(array->container)
(statement->recursion)
(if->while)
(expression->function) replacing an expression with a function or algorithm
(variable->assignment) replacing the value of a variable.
Transformations

15. https://8thlight.com/blog/uncle-
bob/2013/05/27/TheTransformationPriorityPremise.html
https://en.wikipedia.org/wiki/Transformation_Priority_Premise
https://www.youtube.com/watch?v=B93QezwTQpI
https://vimeo.com/97516288
https://vimeo.com/60561303
Transformations Priority Premise
Robert C. Martin (Uncle Bob)

16. @JesusWasRasta
DOmande?
@JesusWasRasta