This presentation was used for a workshop on Test Driven Development, using the Fizz Buzz Coding Dojo Kata.

1. Test Driven Development

2. Introductie
● Wat is TDD?
● Waarom TDD?
● Workshop

3. Wat is TDD?
Wikipedia: a software development process that relies on
the repetition of a very short development cycle: first the
developer writes an (initially failing) test case that defines a
desired improvement or new function, then produces the
minimum amount of code to pass that test, and finally
refactors the new code to acceptable standards

4. Wat is TDD?
Wikipedia: a software development process that relies on
the repetition of a very short development cycle: first the
developer writes an (initially failing) test case that
defines a desired improvement or new function, then
produces the minimum amount of code to pass that test,
and finally refactors the new code to acceptable standards

5. Wat is TDD?
Wikipedia: a software development process that relies on
the repetition of a very short development cycle: first the
developer writes an (initially failing) test case that defines a
desired improvement or new function, then produces the
minimum amount of code to pass that test, and finally
refactors the new code to acceptable standards

6. Wat is TDD?
Wikipedia: a software development process that relies on
the repetition of a very short development cycle: first the
developer writes an (initially failing) test case that defines a
desired improvement or new function, then produces the
minimum amount of code to pass that test, and finally
refactors the new code to acceptable standards

7. Waarom TDD
NIET testen:

8. Waarom TDD

9. De workshop - Coding Dojo regels
Groepjes van twee
Computer wisselt met elke stap
Alle code moet getest zijn
Er zijn meerdere oplossingen mogelijk
Probeer eens iets nieuws

10. De opdracht
Toon een opeenvolgende rij van getallen
Als een getal deelbaar is door 3, toon "Fizz"
Als een getal deelbaar is door 5, toon "Buzz"
Als een getal deelbaar is door 3 en 5, toon
"FizzBuzz"

11. Voorbeelduitkomst
"1"
"11"
"Fizz"
"31"
"41"
"2"
"Fizz"
"22"
"32"
"Fizz"
"Fizz"
"13"
"23"
"Fizz"
"43"
"4"
"14"
"Fizz"
"34"
"44"
"Buzz"
"FizzBuzz"
"Buzz"
"Buzz"
"FizzBuzz"
"Fizz"
"16"
"26"
"Fizz"
"46"
"7"
"17"
"Fizz"
"37"
"47"
"8"
"Fizz"
"28"
"38"
"Fizz"
"Fizz"
"19"
"29"
"Fizz"
"49"
"Buzz"
"Buzz"
"FizzBuzz"
"Buzz"
"Buzz"

12. Voorbeeldoplossing - stap 1
Schrijf een (falende) test:
test_fizz_buzz.rb:
require_relative "fizz_buzz"
console:
E
require "test/unit"
Finished tests in 0.000378s, 2642.4268 tests/s,
0.0000 assertions/s.
class TestFizzBuzz < Test::Unit::TestCase
1) Error:
test_number_3(TestFizzBuzz):
NoMethodError: undefined method `print for
FizzBuzz:Class
test_fizz_buzz.rb:6:in `test_number_3'
def test_number_3
assert_equal "Fizz", FizzBuzz.print(3)
end
end
1 tests, 0 assertions, 0 failures, 1 errors, 0
skips

13. Voorbeeldoplossing - stap 2
Schrijf de minimale code om de test te laten lukken:
fizz_buzz.rb:
class FizzBuzz
def self.print(number)
return "Fizz" if number == 3
end
end
console:
.
Finished tests in 0.000306s, 3266.2660 tests/s,
3266.2660 assertions/s.
1 tests, 1 assertions, 0 failures, 0 errors, 0
skips

14. Voorbeeldoplossing - stap 3
Wat gebeurt er als we 6 meegeven?
test_fizz_buzz.rb:
class TestFizzBuzz < Test::Unit::TestCase
def test_number_3
assert_equal "Fizz", FizzBuzz.print(3)
end
def test_number_6
assert_equal "Fizz", FizzBuzz.print(6)
end
end
console:
.F
Finished tests in 0.000525s, 3808.0804 tests/s,
3808.0804 assertions/s.
1) Failure:
test_number_6(TestFizzBuzz) [test_fizz_buzz.rb:
10]:
<"Fizz"> expected but was
<nil>.
2 tests, 2 assertions, 1 failures, 0 errors, 0
skips

15. Voorbeeldoplossing - stap 4
Herschrijf de code:
fizz_buzz.rb:
class FizzBuzz
def self.print(number)
return "Fizz" if (number % 3 == 0)
end
end
console:
..
Finished tests in 0.000342s, 5851.4436 tests/s,
5851.4436 assertions/s.
2 tests, 2 assertions, 0 failures, 0 errors, 0
skips

16. Voorbeeldoplossing - stap 5
Schrijf de test voor nummer 5:
test_fizz_buzz.rb:
class TestFizzBuzz < Test::Unit::TestCase
def test_number_5
assert_equal "Buzz", FizzBuzz.print(5)
end
end
console:
.F.
Finished tests in 0.000589s, 5092.4794 tests/s,
5092.4794 assertions/s.
1) Failure:
test_number_5(TestFizzBuzz) [test_fizz_buzz.rb:
14]:
<"Buzz"> expected but was
<nil>.
3 tests, 3 assertions, 1 failures, 0 errors, 0
skips

17. Voorbeeldoplossing - stap 6
Schrijf de code voor nummer 5:
fizz_buzz.rb:
class FizzBuzz
def self.print(number)
return "Fizz" if (number % 3 == 0)
return "Buzz" if number == 5
end
end
console:
...
Finished tests in 0.000352s, 8522.3157 tests/s,
8522.3157 assertions/s.
3 tests, 3 assertions, 0 failures, 0 errors, 0
skips

18. Voorbeeldoplossing - stap 7
Wat gebeurt er nu bij nummer 10?
test_fizz_buzz.rb:
class FizzBuzz < Test::Unit::TestCase
def test_number_5
assert_equal "Buzz", FizzBuzz.print(5)
end
def test_number_10
assert_equal "Buzz", FizzBuzz.print(10)
end
end
console:
F...
Finished tests in 0.000565s, 7083.0057 tests/s,
7083.0057 assertions/s.
1) Failure:
test_number_10(TestFizzBuzz) [test_fizz_buzz.rb:
18]:
<"Buzz"> expected but was
<nil>.
4 tests, 4 assertions, 1 failures, 0 errors, 0
skips

19. Voorbeeldoplossing - stap 8
Herschrijf de code:
fizz_buzz.rb:
class FizzBuzz
def self.print(number)
return "Fizz" if (number % 3 == 0)
return "Buzz" if (number % 5 == 0)
end
end
console:
....
Finished tests in 0.000387s, 10343.3474 tests/s,
10343.3474 assertions/s.
4 tests, 4 assertions, 0 failures, 0 errors, 0
skips

20. Voorbeeldoplossing - stap 9
Schrijf de test voor 3 en 5:
test_fizz_buzz.rb:
class TestFizzBuzz < Test::Unit::TestCase
def test_number_15
assert_equal "FizzBuzz", FizzBuzz.print(15)
end
end
console:
.F...
Finished tests in 0.000618s, 8085.1594 tests/s,
8085.1594 assertions/s.
1) Failure:
test_number_15(TestFizzBuzz) [test_fizz_buzz.rb:
22]:
<"FizzBuzz"> expected but was
<"Fizz">.
5 tests, 5 assertions, 1 failures, 0 errors, 0
skips

21. Voorbeeldoplossing - stap 10
Schrijf de code voor 3 en 5:
fizz_buzz.rb:
class FizzBuzz
def self.print(number)
return "FizzBuzz" if number == 15
return "Fizz" if (number % 3 == 0)
return "Buzz" if (number % 5 == 0)
end
end
console:
.....
Finished tests in 0.000392s, 12763.0138 tests/s,
12763.0138 assertions/s.
5 tests, 5 assertions, 0 failures, 0 errors, 0
skips

22. Voorbeeldoplossing - stap 11
Wat gebeurt er nu bij 30?
test_fizz_buzz.rb:
class TestFizzBuzz < Test::Unit::TestCase
def test_number_15
assert_equal "FizzBuzz", FizzBuzz.print(15)
end
def test_number_30
assert_equal "FizzBuzz", FizzBuzz.print(30)
console:
...F..
Finished tests in 0.000599s, 10010.2104 tests/s,
10010.2104 assertions/s.
1) Failure:
test_number_30(TestFizzBuzz) [test_fizz_buzz.rb:
26]:
<"FizzBuzz"> expected but was
<"Fizz">.
end
end
6 tests, 6 assertions, 1 failures, 0 errors, 0
skips

23. Voorbeeldoplossing - stap 12
Schrijf de code voor 30:
fizz_buzz.rb:
class FizzBuzz
def self.print(number)
return "FizzBuzz" if (number % 3 == 0) &&
(number && 5 == 0)
return "Fizz" if (number % 3 == 0)
return "Buzz" if (number % 5 == 0)
end
end
console:
......
Finished tests in 0.000423s, 14191.6775 tests/s,
14191.6775 assertions/s.
6 tests, 6 assertions, 0 failures, 0 errors, 0
skips

24. Voorbeeldoplossing - stap 13
Refactor de code voor 30:
fizz_buzz.rb:
class FizzBuzz
def self.print(number)
return "FizzBuzz" if (number % 15 == 0)
return "Fizz" if (number % 3 == 0)
return "Buzz" if (number % 5 == 0)
end
end
console:
......
Finished tests in 0.000423s, 14191.6775 tests/s,
14191.6775 assertions/s.
6 tests, 6 assertions, 0 failures, 0 errors, 0
skips

25. Voorbeeldoplossing - stap 14
Wat als we een foutje hadden gemaakt?
fizz_buzz.rb:
console:
F.F.FF
class FizzBuzz
Finished tests in 0.000999s, 6007.5034 tests/s, 6007.5034 assertions/s.
def self.print(number)
return "FizzBuzz" if (number % 3 == 0) ||
(number % 5 == 0)
return "Fizz" if (number % 3 == 0)
return "Buzz" if (number % 5 == 0)
end
end
1) Failure:
test_number_10(TestFizzBuzz) [test_fizz_buzz.rb:18]:
<"Buzz"> expected but was
<"FizzBuzz">.
2) Failure:
test_number_3(TestFizzBuzz) [test_fizz_buzz.rb:6]:
<"Fizz"> expected but was
<"FizzBuzz">.
3) Failure:
test_number_5(TestFizzBuzz) [test_fizz_buzz.rb:14]:
<"Buzz"> expected but was
<"FizzBuzz">.
4) Failure:
test_number_6(TestFizzBuzz) [test_fizz_buzz.rb:10]:
<"Fizz"> expected but was
<"FizzBuzz">.
6 tests, 6 assertions, 4 failures, 0 errors, 0 skips

26. Voorbeeldoplossing - stap 15
Schrijf de test voor alle andere getallen:
test_fizz_buzz.rb:
console:
..F....
class TestFizzBuzz < Test::Unit::TestCase
Finished tests in 0.000631s, 11091.4634 tests/s, 11091.4634 assertions/s.
def test_number_2
assert_equal "2", FizzBuzz.print(2)
end
1) Failure:
test_number_2(TestFizzBuzz) [test_fizz_buzz.rb:30]:
<"2"> expected but was
<nil>.
7 tests, 7 assertions, 1 failures, 0 errors, 0 skips
end

27. Voorbeeldoplossing - stap 16
Schrijf de code voor alle andere getallen:
fizz_buzz.rb:
console:
.......
class FizzBuzz
Finished tests in 0.000520s, 13452.1220 tests/s, 13452.1220 assertions/s.
def self.print(number)
return "FizzBuzz" if (number % 15 == 0)
return "Fizz" if (number % 3 == 0)
return "Buzz" if (number % 5 == 0)
return number.to_s
end
end
7 tests, 7 assertions, 0 failures, 0 errors, 0 skips

28. Voorbeelduitkomst - next steps
➢ Elke individuele regel naar een aparte methode
abstraheren
➢ De complete lijst laten zien met het uitvoeren van een
bestand
➢ User Interface

29. Voorbeeldoplossing - stap 17
Itereren over 100 getallen:
fizz_buzz.rb:
class FizzBuzz
def self.print(number)
return "FizzBuzz" if (number % 15 == 0)
return "Fizz" if (number % 3 == 0)
return "Buzz" if (number % 5 == 0)
return number.to_s
end
end
(1..100).each{|number| puts FizzBuzz.print(number)}
console:
ruby fizz_buzz.rb
1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
16
17
Fizz
19
Buzz
Fizz
22
23
...etc