Karumi Dojo - String Calculator Kata

1. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Karumi Dojo
Pedro Vicente Gómez Sánchez
Senior Android Developer at Karumi
pedro@karumi.com
@pedro_g_s
github.com/pedrovgs

2. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs

3. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Irene Herranz
Managing Director
Alberto Gragera
Technical Director
Jorge Barroso
Android Expert
Davide Mendolia
Full Stack Engineer

4. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs

5. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Karumi Dojo
● We are here to practice and learn.
● This is a bullshit free environment.
● This exercise meant to be collaborative, not
competitive.
● Try to open your mind to new concepts.

6. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Karumi Dojo
● We are here to practice Test-Driven Development.
● TDD is a software development process, not a dogma.
● We are going to practice pair programming.
● Keep always in mind the TDD Cycle.

7. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Rules:
● Write enough test code so that to get a single test
failure.
● Write enough production code to get all your tests to
pass.
● Refactor until the code is Simple/Clean.

8. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Rules: The TDD Cycle
RED
GREEN
REFACTO
R
3. Simplify and clean
your code.
1. Write a failing test.
2. Make the code work.

9. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Sum the number inside string passed as parameter: 1,2,3 = 6
String Calculator
public int add(String numbers) {
//Put your code here
}

10. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Business Rule 1
The method can take 0, 1 or 2 numbers,
and will return their sum (for an empty
string it will return 0) for example “” or “1”
or “1,2”.

11. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Business Rule 2
Allow the Add method to handle an
unknown amount of numbers.

12. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Business Rule 3
Allow the Add method to handle new lines
between numbers (instead of commas).

13. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Business Rule 4
Calling Add with a negative number will
throw an exception “negatives not
allowed” - and the negative that was
passed. If there are multiple negatives,
show all of them in the exception
message

14. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Rule 5
If the delimiter used is not “,” or “n”
throw an exception.

15. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Tips
● Baby steps.
● Don’t lose the green.
● Choose the language you prefer.
● Refactor your code.
● Build errors are not failing tests.
● Follow the TDD Cycle.

16. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
http://goo.gl/erofJ5

17. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Extra points

18. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Extra Rule 1
Numbers bigger than 1000 should be
ignored, so adding 2 + 1001 = 2

19. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Extra Rule 2
To change a delimiter, the beginning of the string
will contain a separate line that looks like this: “//
[delimiter]n[numbers…]” for example “//;n1;2”
should return three where the default delimiter is ‘;’ .
The first line is optional. all existing scenarios
should still be supported

20. Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
Extra Rule 3
Allow multiple delimiters like this:
“//[delim1][delim2]n” for example “//[*][%]
n1*2%3” should return 6.