Testing and Refactoring sharing

• Bi-weekly Tech Sharing

Agenda

• Experience
• Testing
• Refactoring
• References

Experience

• best thing learned this year

• I’m proud that we have testing culture and code review

• how I test my code before?

  • coding -> run program -> postman / repl -> verify by eye -> QA

• how I test my code now?

  • coding -> add tests -> green -> refactoring -> coding -> repeat -> code review

• hopefully I’ll benefit from TDD style sooner

Testing

• raise a question: we’re relying on tests to guarantee code work as expected, who guarantees our tests are correct then?

  • short answer: we can only rely on simple tests
  • too simple to be wrong(ideal world)

• testing proportion

• testing helped on

  • building confidence
  • building solid(bug free) code as possible
  • gives me a button to click
    • “if you ever get that button, you’ll never want to lose it or work other way round so you wouldn’t have it.”

• testing drives me to write simple code

  • I want class to be small
  • I want responsiblilty to be single/simple/clear
  • I want method to be short
  • I want interface to be well defined
  • I love good names

• example of using let(private git repo pull request)

  • demo for independant tests
  • avoid mutable variable
  • discipline posed upon assignment/mutability

• key points:

  • write simple code & test when possible
  • more unit tests
  • “write enough tests to be confident”

Refactoring

• let’s put performance aside while coding & refactoring

• let’s focus on clarity/simplicity/readability/maintainability, not performance

  • make it simple
  • make it easier to read/review
  • make it easier to change/maintain

• How I do code refactoring?

  • clean up feature flags
  • check code coverage and make it up to 100%
  • remove code smell
  • simplify code
  • enjoy the tiny changes/improvements
  • enjoy the green dots
  • enjoy the red dots(it shows I didn’t fully understand my code)
  • remove unused/dead code(unused)
  • check with flog(rely on metric tools, not “feeling”)
  • choose a better name for variables/methods/class/file/moudles
  • simplify tests
  • I got better understanding of the code, and I can repeat the above process…

• example of simplifying code(private git repo pull request)

• The point is: “business complixity is the lower limit of system complixity”

  • so I want my code to be as simple/readable as possible
  • try functional thinking: e.g. use filter/map/reduce
  • ruby: Enumerable module is amazing

• key points:

  • lean on tests, no tests, no refactoring
  • do your refactoring with small steps(highlighted in both “refactoring” and “99 bottles of OOP”)
  • refactoring is just pattern matching(focus on code smell) and follow the solution

References

• book: 99 Bottles of OOP — Sandi Metz
• book: Refactoring
• gitrepo: A tool to identify potentially unused code.
• gitrepo: sandimetz/99bottles_ruby
• guide: Better Specs. Testing Guidelines for Developers.
• paper: algorithm = logic + control.pdf
• post: “You Don’t Know What You Don’t Know”
• post: Let vs. Let! vs. Instance Variables in RSpec
• post: Simplifying Tests by Extracting Side-Effects
• post: 测试指南 - Rei
• quote: “Do yourself a favor and make sure your test coverage is good before you start an upgrade.”
• quote: “Pain in your tests should push you to change the design of objects being tested”
• quote: “if you ever get that button, you’ll never want to lose it or work other way round so you wouldn’t have it.”
• quote: “Running our test table: Click the Test button”
• slide: slide page7: “Focus on Simplicity & Clarity, Otherwise, you don’t fully understand.“
• talk: “Fearless Competence / Conquer the fear with Test.”
• talk: Clean Code - Uncle Bob - YouTube
• tool: Catalog of Refactorings
• tool: Confessions of a Ruby Sadist sudo gem install flog
• wiki: Code Smell
• wiki: Rules Of Optimization
• wiki: Test Driven Development

At last

these are just my limited experience on testing & refactoring; I’m pretty sure I have a lot more to learn

I really want to learn from everyone about these two topics

pls correct me if I’m wrong. pls discuss with me if you’re interested~ Orz