Introduction to Test-driven Development

Transcript

1. Introduction to Test Driven Development
2. What is TDD? § It is an iterative development technique § Focused on design rather than validation § Also referred as: Test first development
3. TDD effects § Improve and speed up software development § Have flexible and extensible code § Reduce bugs § Improve documentation
4. TDD mantra § Write test before implementation § Refactor, refactor, refactor § Relies on unit testing and unit testing frameworks § ”Unit tests run fast, if they do not run fast they are not unit tests”
5. TDD: step 1 § Think in terms of baby steps § Focus on the behaviour you wish your code will have THINK
6. TDD: step 2 § Write a test, watch it fail § Focus on the behaviour your class and method will have § A.K.A. name your API properly THINK FAIL
7. TDD: step 3 § Write the code, make it pass § Write the minimal amount of code that makes the test pass THINK FAIL PASS
8. TDD: step 4 § Simplify and improve the design § Do NOT modify the behaviour! THINK FAIL PASS REFACTOR
9. TDD cycle THINK FAIL PASS REFACTOR
10. Limitations § Steep learning curve § It requires discipline to conform to the process § Hard to apply to GUI development § Hard to apply to legacy code
11. References § Kent Beck: Test driven development by example § Dave Astels: Test driven development, a practival guide
12. Exercise For this exercise you will implement as simplified version of a tennis game using Test-driven development: §  A game is won by the first player to have won at least four points in total and at least two points more than the opponent. §  The running score of each game is described in a manner peculiar to tennis: scores from zero to three points are described as "love", "fifteen", "thirty", and "forty" respectively. §  If at least three points have been scored by each player, and the scores are equal, the score is "deuce". §  If at least three points have been scored by each side and a player has one more point than his opponent, the score of the game is "advantage" for the player in the lead.