Testing your code

Unit Testing become Test Driven Development. Introduction to the concept of Unit testing with some examples of PHPUnit. Finishing with a Kata TDD (FizzBuzz). Prepared for a class with 3 hours of duration or 4h repeating the Kata.

Transcript

1. Testing your code Alejandro Pérez Batanero - 2/03/2015
2. How do we code? Design Implement Test
4. Problems • We are the worst testing our own code. We may forget corner cases. • We test our code as a whole instead of small parts. • To check if everything works fine takes long time, more as the project grows.
5. Unit test Unit Testing is a method by which individual units of source code are tested to determine if they are fit for use. A unit is the smallest testable part of an application - Wikipedia
6. Why should we unit test? • You can check easily if your code works • A unit test is the best updated documentation and guide to understand your code. • We can add new features checking if the old ones still work. • If features break the unit test will tell us where the error is. • Gives us the confidence to refactor code that we don’t know.
7. How should be a unit test? • Isolated: Not depend on other classes. • Repeatable: No side effects • Understable: Clean code your test • Reliable: If something is wrong, must fail
8. Steps 1. Setup: Get everything you need to test the features (instantiate, configurations,...) 2. Run: Execute the System Under Test (SUT) 3. Assertion: Check that your system do what is supposed to do
9. AlexUnit • Very simple testing framework for unit testing github.com/alexgt9/AlexUnit
10. PHPUnit • Web: https://phpunit.de/ • Installation: https://phpunit.de/manual/current/en/installation.html • Prepare your environment for the coming practice • Linux: ◦ wget https://phar.phpunit.de/phpunit.phar ◦ php phpunit.phar --version
11. Mocks
12. Mocks - Doubles • Replace the original class • Avoid side effects (database) • Control interactions between classes
13. What can a method do? • Return a value • Modify internal state • Print something • Throw exception • Call other classes
14. What can a method do? • Return a value • Modify internal state • Print something • Throw exception • Call other classes That is not the final behavior
15. What can a method do? • Return a value • Print something • Throw exception • Call other classes Should not
16. How to test these behaviours? • Return a value • Throw exception • Call other classes ➔ Assertions ➔ Assertions ➔ Using doubles
17. Double Types • Dummy • Stub • Mock • And more...
18. Dummy • Don’t do nothing • Probably a type hinting contract
19. Dummy
20. Dummy
21. Stub • Return custom results that guide the test • Can throw exceptions • Can be called and don’t return anything
22. Stub
23. Stub
24. Mock • Stubs with expectations • Check interactions
25. Mocks
26. Mocks
27. Testing pyramid
28. My two cents • Simple and easy => Maintainable • Testing code is also “Production code” • Test for other developers • SOLIDify your tests • One test => One feature • Use less assertions as possible • Love your tests <3
29. Test driven development Design Implement Test
30. Test driven development Design Implement Test Test
31. Test Driven Development 1. Red ◦ Write a failing test. Mock all related dependencies. Use baby steps. 2. Implement ◦ Write the minimum code to make the test pass. Don’t make it beautiful, just pass the test. 3. Green ◦ Run the test to check that everything works fine. 4. Refactor (very important) ◦ Now it’s time to make it beautiful, improve your code. This applies to the test itself too.
32. Test driven development Design Implement Test Test Refactor
33. Kata TDD • Try to resolve a problem in 45 minutes • Using TDD, so first code your tests • Using pair programming • Make baby steps, from little easy test • Refactor code - Refactor test
34. Fizz Buzz • Write numbers from 1 to 100 • For multiples of 3, print “Fizz” instead of the number • For multiples of 5, print “Buzz” instead of the number • For multiple of 3 and 5 print “FizzBuzz” instead of the number • Ex.: 1, 2, Fizz, 4, Buzz, Fizz, … 13, 14, FizzBuzz, 16 Base environment https://github.com/alexgt9/kata-fizzbuzz