Presentation originally developed for a presentation at AgileDC 2016. Presentation abstract: Does your team treat test code differently than production code? Do you let your test code accumulate duplication and complexity that you'd normally attempt to squash in your production code? Have your tests become brittle? Are you worried that they aren't providing you the same value they used to? Have you strongly considered dumping your test suite and starting over? Are you afraid that if you refactor your test code, you'll introduce false positives? If you said yes to any of those questions, then this talk is for you. We'll explore the technique of "refactoring against the red bar" (http://butunclebob.com/ArticleS.MichaelFeathers.RefactoringAgainstTheRedBar), and how you can employ this technique to confidently refactor your test code. No longer do you need to let your test code have a lower standard of quality than your production code.

1. EMBRACING THE RED BAR
A TECHNIQUE FOR SAFELY
REFACTORING YOUR TEST CODE
M. Scott Ford (@mscottford) | Chief Code Whisperer and CTO | Corgibytes (@corgibytes)

2. CREDITS
LIZ KEOGH ( ) -
MICHAEL FEATHERS ( ) -
@LUNIVORE ORIGINAL ARTICLE
@MFEATHERS ORIGINAL ARTICLE

3. JARGON ALERT
WHAT'S A RED BAR?

4. GREEN BAR: ALL TESTS PASSING

5. RED BAR: SOME TESTS FAILING

6. BEWARE OF OVERCONFIDENCE
A CAUTIONARY TALE

7. TEST CODE VS PRODUCTION CODE

8. KEEP YOUR TEST CODE CLEAN

9. NORMAL TDD CYCLE

10. NSURES THAT YOUR TESTS WILL FAIL IF YOUR PRODUCTION CODE BREAK
ALLOWS YOU TO REFACTOR YOUR PRODUCTION CODE WITH IMPUNITY

11. RED-BAR CYCLE

12. RED, REFACTOR, GREEN
ENSURES THAT YOUR TEST CODE CONTINUES
TO DETECT THE FAILURE CONDITION WHILE
REFACTORING THE TEST CODE

13. RED
MUTATE THE PRODUCTION CODE
Produces a red bar
Ensures that your test can fail

14. REFACTOR
REFACTOR YOUR TESTS
Continue to see the red bar
Ensures that your tests are still failing

15. GREEN
REVERSE THE PRODUCTION CODE MUTATION
Bar should switch to green
Your test should now pass

16.
THINGS THAT CAN GO WRONG

17. RED
I want to refactor a test, but I can't make it fail

18. REFACTOR
I'm refactoring a test, and it's started passing

19. GREEN
I reverted my production change, and my tests are still failing

20. CALCULATOR EXAMPLE

21. STARTING POINT
class Calculator
def add(left, right)
end
end

22. FAILING TEST
describe 'additon' do
specify 'adding two numbers that result in 4' do
calculator = Calculator.new
result = calculator.add(2, 2)
expect(result).to eq(4)
end
end

23. WATCH IT FAIL

24. MAKING IT PASS
class Calculator
def add(left, right)
return 4
end
end

25. WATCH IT PASS

26. MAKE THE TESTS BETTER
describe 'additon' do
specify 'adding two numbers that result in 4' do
calculator = Calculator.new
result = calculator.add(2, 2)
expect(result).to eq(4)
end
specify 'adding two numbers that result in 5' do
calculator = Calculator.new
result = calculator.add(2, 3)
expect(result).to eq(5)
end
end

27. WATCH THEM FAIL

28. MAKE THEM PASS
class Calculator
def add(left, right)
return left + right
end
end

29. WATCH THEM PASS

30. LET'S REFACTOR OUR TESTS

31. BREAK THE PRODUCTION CODE
class Calculator
def add(left, right)
return 0 # was: left + right
end
end

32. WATCH THE TESTS FAIL

33. APPLY THE REFACTORING
describe 'additon' do
let(:calculator) { Calculator.new }
specify 'adding two numbers that result in 4' do
result = calculator.add(2, 2)
expect(result).to eq(4)
end
specify 'adding two numbers that result in 5' do
result = calculator.add(2, 3)
expect(result).to eq(5)
end
end

34. VERIFY THAT THE TESTS STILL FAIL

35. RESTORE PRODUCTION CODE
class Calculator
def add(left, right)
return left + right
end
end

36. WATCH THE TESTS PASS

37.
QUESTIONS?

38. CONTACT INFO
M. Scott Ford
Twitter: @mscottford
Blog: http://corgibytes.com/blog