Introduction to TDD: Red-Green-Refactor

Transcript

1. TDD 101 1. Test Driven Development
2. Test Driven Development
3. Test Driven Development It’s a discipline Unit test first Only code to pass the test Loop of minimal changes
4. Classic post-test vs TDD Test Code Design Design Code Test Waterfall TDD
5. TDD laws
6. TDD laws You can't write any production code until you have first written a failing unit test. You can't write more of a unit test than is sufficient to fail, and not compiling is failing. You can't write more production code than is sufficient to pass the currently failing unit test. Robert C. Martin
7. TDD cycle
8. TDD cycle Write a failing test Write just enough code to make the test pass Refactor if needed
 (mostly reduce duplication)
9. Write a failing test Write a test to prove a simple case Run the test and see how it fails Errors == test fails
10. Make the test pass Write production code until: • all errors are fixed • the test passes
11. Refactor Keep tests passing Remove duplication Improve design
12. Outcomes
13. Outcomes Always backed by tests Decoupled design Automatically you get: • full coverage • regression tests
14. Code
15. Write a failing test class ValidateNifTest extends TestCase { public function testRealNIFShouldBeValid() { $validateNif = new ValidateNif(); $this->assertTrue($validateNif->isValid('00000000T')); } } Error : Class 'Dojo\ValidateNif\ValidateNif' not found /Users/franiglesias/PhpstormProjects/dojo/tests/Dojo/ValidateNif/ValidateNifTest.php: 13
16. Make the test pass class ValidateNif { } Error : Call to undefined method Dojo\ValidateNif\ValidateNif::isValid() /Users/franiglesias/PhpstormProjects/dojo/tests/Dojo/ValidateNif/ValidateNifTest.php: 14
17. Make the test pass Failed asserting that null is true. /Users/franiglesias/PhpstormProjects/dojo/tests/Dojo/ValidateNif/ValidateNifTest.php: 14 class ValidateNif { public function isValid(string $nif) { } }
18. Make the test pass OK (1 test, 1 assertion) class ValidateNif { public function isValid(string $nif):bool { return true; } }
19. Hands on…
20. Fizz Buzz Kata stage 1 Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz “. http://codingdojo.org/kata/FizzBuzz/
21. Fizz Buzz Kata
 stage 2 A number is “Fizz" if it is divisible by 3 or if it has a 3 in it A number is “Buzz” if it is divisible by 5 or if it has a 5 in it http://codingdojo.org/kata/FizzBuzz/
22. Fizz Buzz Kata
 stage 3 We want all these rules configurable. http://codingdojo.org/kata/FizzBuzz/