tdd is for dreamers, not for real developers, isn't it? - entwicklertag frankfurt 2017
Post on 12-Apr-2017
209 Views
Preview:
TRANSCRIPT
TDD is for Dreamers,not for Real Developers,
Isn’t It?
Sven Amann academicscode.com
letsdeveloper.com @svamann
artwork by Sven Amann - CC BY-SA 4.0
“Faster development, higher code quality, better design, and less waste!” Kent Beck
“Self-testing code and clean interfaces!” Martin Fowler
“Exhaustive test suites, close to no debugging, changing code without fear, reduced coupling, …” Uncle Bob
“Fast feedback and safe refactoring” James Shore
“TDD is dead. Long live testing” DHH
“TDD needs a funeral.” Cope
“The real "problems" with TDD [is] in the "driven" part, not the "test" part [and] the zealotry of some of its evangelists” Rich Hickey
Agile Alliance TDD1976: The Dark Age of Developer Testing
“a developer should never test their own code” Glenford Myers in “Software Reliability”
1994 - Kent Beck develops SUnit
1999 - Kent says “test first” in “XP Explained”
until 2002 - “test first” evolves to “test driven”
Source: https://www.agilealliance.org/glossary/tdd/
Queueing Theory
Source: http://blog.jbrains.ca/permalink/how-test-driven-development-works-and-more
Test-first Programming
Source: http://blog.jbrains.ca/permalink/how-test-driven-development-works-and-more
Uncle Bob’s Three Laws of TDD
1. You are not allowed to write any production code unless it is to make a failing unit test pass.
2. You are not allowed to write any more of a unit test than is sufficient to fail; and compilation failures are failures.
3. You are not allowed to write any more production code than is sufficient to pass the one failing unit test.
Source: http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd
ClassicTDD Test: 1 = “I”
return “I”;
Test: 2 = “II”
return (i == 1) ? “I” : “II”;
Test: 3 = “III”
return i * “I”;
...
ClassicTDD
• Roman Numbers • FizzBuzz • Bowling Game • Game of Life • Harry Potter Book Sets • …
Algorithms with well-defined input-output relation
–John Sonmez
“By writing unit tests ... you find all kinds of problems with that code ... of those units [but] unit testing is more of an appraisal activity than a testing one... very few regressions are caught
by unit tests since changing the unit of code you’re testing almost always involves changing
the unit test itself.”
“a developer should never test their own code” –Glenford Myers
artwork by Sven Amann - CC BY-SA 4.0
self control
Test-driven Programming
Source: http://blog.jbrains.ca/permalink/how-test-driven-development-works-and-more
–James O. Coplien (Cope)
“TDD was created to replace up-front architecture. It is not a testing technique.”
Source: https://twitter.com/jcoplien/status/828291686128304130
class Persondef ageDate.today.year - birthday.yearendend
test “a person’s age is determined by birthday” doseventy_niner = Person.new birthday: Date.new(1979)travel_to Date.new(2009)assert_equal 30, seventy_niner.ageend
artwork by Sven Amann - CC BY-SA 4.0
class Persondef age(now = Date.today)now - birthday.yearendend
test “a person’s age is determined by birthday” doseventy_niner = Person.new birthday: Date.new(1979)assert_equal 30, seventy_niner.age Date.new(2009)end
First Design, then Code, then Test. That’s how
we’ve always done it.
artwork by Sven Amann - CC BY-SA 4.0
Traditional Waterfall Testing
Agile Over-Enthusiast
All but that…
–David Heinemeier Hansson (DHH)
“Writing software is more like writing french poetry than a hard science.”
–Joe Rainsberger (jbrains)
“TDD Is Not Magic. The rules themselves do not guarantee success. You have to keep the brain switched on. You have to pay attention to what’s happening. You need a place to ask questions
and get answers. You need to know that when you practise TDD, your code starts to speak to you, but in a language you [may not yet] understand, and that when you write tests and run them, this act equates to learning a language by hearing it,
trying to speak it, and by native speakers correcting you. If you do these things, then I
expect TDD to “work” for you.”
top related