In the Driver's Seat: How MSPec and BDD Will Make You a Better Programmer

Transcript

1. How MSpec and BDD Will Make You a Better Programmer Joe Leo IN THE DRIVER’S SEAT: @jleo3
2. Joe Leo @jleo3 linkedin.com/in/jleo3 github.com/jleo3 joseph.leo3@gmail.com TestDrivenDomination.com
3. FIRST PRESENTATION, EVER!
4. Two Quick Plugs
5. Surprise! We’re Hiring! • Great money, benefits! • Genuine agile work environment! • Personal Chauffers! • Swimming pools filled with champagne! • Work in .NET, Java, Scala, and more! • Work with ME!
6. www.devlink.net August 28-30 Chattanooga, TN Only $100!!
7. Impressive Speakers • Scott Hanselman • Nicholas Zakas • Josh Carroll
8. Tennessee Valley Railroad Museum
9. Raccoon Mountain Caverns
10. International Towing and Recovery Museum
11. LAST PRESENTATION, EVER? FIRST PRESENTATION, EVER!
12. Outline • Who's this guy and why should we listen to someone with crazy hair and a huge beard? • What can writing Ruby teach me about .NET? • An Intro to MSpec: "Poking the Tiger" • Get Drunk with Einstein
13. Where Does This Guy Come From? • From Ruby Land. • In RoR, where the tests roam free
14. Auto generated Tests/Specs
17. In Ruby, 100% test coverage is just a good start.
18. Great Testing, Sport!
19. Ruby is… UN
20. S.O.L.I.D. Design Principles • 5 Basic principles of object oriented design • Often attributed to Uncle Bob Martin • Actually a mnemonic created by Michael Feathers • Michael Feathers is awesome so stop giving Martin all the credit!
21. S.O.L.I.D. continued • Single Responsibility • Open-closed principle • Liskov Substitution • Interface Segregation • Dependency Inversion
22. “Everything is an Object. Rejoice!” • Ruby is SOLID • No interfaces • Ruby is SOLID SOLD?
23. The Contract Enforcer
24. Testing Zealot (ME)
25. “WE’RE GOING TESTING!”
26. Damn Good Testing LOC, Totals grouped by language: • ruby: 46575 (98.82%) • xml: 354 (0.75%) • sh: 200 (0.42%) Test Coverage: 98.37%
27. Commence Hand-Wringing • “This is just a proof of concept.” • “We have to get this done as quickly as possible.” • “Our team doesn’t do testing that way.” • “Stop talking to me! We’re losing $75,000 a day and I need to find a new job!”
30. Axiom: The best way to produce robust and beautiful code is to start with elegantly crafted tests.
31. This is MSpec “Machine.Specifications is a Context/Specification framework geared towards removing language noise and simplifying tests.” • Inspired by RSpec • Emphasis on grammar – Subject, Establish, Because, It • Plug-N-Play with mocking frameworks
32. MSpec Mocks are Plug-n-Play • RhinoMocks (default) • Moq • FakeItEasy
33. Wordy Gurdy • Given / When / Then • Describe / It / Should • Test / Setup / Assert • Establish / Because / It
37. My First Mspec: “Poking the Tiger”
38. Iteration 1
39. Make Because/It One Line Apiece “MSpec is designed to reduce noise in tests. You should generally only have one line in your It and Because statements... Context/Specification testing, while a rethinking of "classic" TDD, still abides by the rules of Arrange-Act-Assert. As such, it is preferable to keep the latter two as succinct as possible.”
40. Iteration1
41. RSpec Describe Wrap sets of shared functionality
42. Single Responsibility Principle "There should never be more than one reason for a class to change." -- Uncle Bob Martin
44. class FortranPythonBreakfastMakingRocketLauncher
46. More Subtle... class User
47. Use the Describe
49. Quick Tips • Beware of Unhappy Resharper • github.com/jleo3/mspec_dot_settings • STOP WHAT YOU’RE DOING AND GET NCRUNCH!
50. Iteration 2
51. Iteration 2
52. Iteration3
53. Iteration3
54. Axioms • Specs should involve the least amount of setup possible for executing expectations. • Specs that exercise the same responsibility should have similar setups.
55. • FizzBuzz: Simple Programming Problem • FizzBuzz: Not as easy as it looks • FizzBuzz: Gauntlet of Death
57. FizzBuzz with Einstein It’s the summer of 1923. You and a few friends are on holiday in Goeteborg, Sweden. After one round of starköl in the Nobel Bar you start to feel funny. So you make fun of people around you – loudly. As you spot someone who has that distinct Einstein-haircut you tell him that "only two things are infinite, the universe and your stupidity, and I’m not sure about the former". As it turns out this man is indeed Einstein celebrating after his nobel price acceptance speech – and now he is mad at you. To settle this issue like civilized gentlemen he proposes a little drinking game called "fizz-buzz". In order to leave the table without a serious alcohol poisoning but some of your pride left you decide to do what every person would do: Cheat!
58. The Rules • One person calls out a number • The other person determines the next 3 numbers based on the following: o If the number is divisible by three, say "Fizz" o If the number is divisible by five, say "Buzz" o If the number is divisible by both, say "FizzBuzz" o If none of the above are met, repeat the number. If you’re wrong, you drink. If you’re right the other person drinks.
59. In broader terms At any given time there will be 3 rules x, y, and z such that for a given input i o If x(i) and y(i) then z(i) o If x(i) and !y(i) then x(i) o If !x(i) and y(i) then y(i) o If !x(i) and !y(i) then i
60. Test Last
61. Test First
62. Test First
63. Axioms • Fewer requirements lead to smaller objects. • Smaller objects have a better chance of being SOLID.
64. Test First
65. Keep Your Code DRY Photo credit: deviq.com
66. Test First
67. Red, Green, Refactor
68. Beating Einstein to a Drunken Pulp
69. Axioms • Specs should involve the least amount of setup possible for executing expectations. • Specs that exercise the same responsibility should have similar setups.
70. Beating Einstein to a Drunken Pulp
71. Wrapping Up • Learning Ruby is good for you. • Poking Tigers is dangerous but safer if you use interfaces. • Don’t make fun of Einstein until you’ve had some experience with BDD • Even guys with crazy beards and giant curly hair are occasionally useful.
72. Code and Slides Available • github.com/jleo3/DemoMSpec • github.com/jleo3/myfizzbuzz • Speaker deck
73. Finally… • I want your feedback! • http://bit.ly/134aAuQ • Your feedback == $$ for the American Red Cross Disaster Relief fund.
74. Thank You! Joe Leo @jleo3 linkedin.com/in/jleo3 github.com/jleo3 joseph.leo3@gmail.com TestDrivenDomination.com Feedback: http://bit.ly/134aAuQ