Slides from my Lightning Talk at AgileBrazil 2011 in Fortaleza about refactoring katas. Check the code on Github at: http://github.com/dtsato/kata-refactoring-calendar

1. Refactoring Katas
Danilo Sato - @dtsato
ThoughtWorks
www.dtsato.com

2. Kata?

3. Kata?

4. Kata?
• Exercícios para praticar
• Melhorar habilidades específicas:
• TDD
• Algoritmos
• Design
• Código Ruim?
• ...

5. Kata?
Test
Test
Test
Test

6. Kata?
Test
Test
Test
Test

7. Kata?
Test
Test
Test
Test

8. Kata?
Test
Test
Test
Test

9. Refatoração
Test

10. Refatoração
Test Code

11. Refatoração
Test Code

12. Refatoração
Code
Test

13. Refatoração
Code
Test

14. Refatoração
Code
Test

15. Refatoração
Code
Test

16. Refatoração
Code
Test

17. Refatoração
Code
Test

18. Refatoração
Code
Test

19. Refatoração
Code
Test
Remover duplicação

20. Outros tipos...
Code
Test

21. Outros tipos...
Code Code
Test

22. Outros tipos...
Code Code
Test Test

23. Outros tipos...
Code Code
Test Test
Se paração de
responsa bilidades

24. Outros tipos...
Code
Test

25. Outros tipos...
Test Code

26. Outros tipos...
Test Code

27. Outros tipos...
Test Code
Mudança no design

28. Ainda mais

29. A idéia

30. A idéia

31. A idéia
?

32. A idéia
? ?

33. A idéia
? ?
?

34. #comofas
1. Criticar código
2. Analisar a solução final
3. Planejar os passos
4. Mão na massa!

35. def index(params)
scope = Event
case params[:timeframe]
when 'tomorrow'
scope = scope.between_day(DateTime.now + 1)
when 'this_week'
scope = scope.between_dates(DateTime.now, ( DateTime.now + 6 ).end_of_day)
when 'custom'
if params[:start_date].blank?
params[:start_date] = DateTime.now.beginning_of_week.strftime('%m/%d/%Y')
end
if params[:end_date].blank?
params[:end_date] = (DateTime.now.end_of_week - 2).strftime('%m/%d/%Y')
end
scope = scope.between_dates(DateTime.strptime(params[:start_date], '%m/%d/%Y'),
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day)
when 'hour'
scope = scope.between_hour_on_day(DateTime.strptime(params[:hour], '%m/%d/%Y %H:
%M'))
when 'today'
scope = scope.between_day(DateTime.now)
end
@events = scope.all
end

36. def index(params)
scope = Event switch/case
case params[:timeframe]
when 'tomorrow'
scope = scope.between_day(DateTime.now + 1)
when 'this_week'
scope = scope.between_dates(DateTime.now, ( DateTime.now + 6 ).end_of_day)
when 'custom'
if params[:start_date].blank?
params[:start_date] = DateTime.now.beginning_of_week.strftime('%m/%d/%Y')
end
if params[:end_date].blank?
params[:end_date] = (DateTime.now.end_of_week - 2).strftime('%m/%d/%Y')
end
scope = scope.between_dates(DateTime.strptime(params[:start_date], '%m/%d/%Y'),
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day)
when 'hour'
scope = scope.between_hour_on_day(DateTime.strptime(params[:hour], '%m/%d/%Y %H:
%M'))
when 'today'
scope = scope.between_day(DateTime.now)
end
@events = scope.all
end

37. def index(params)
scope = Event
case params[:timeframe]
when 'tomorrow'
scope = scope.between_day(DateTime.now + 1)
when 'this_week'
string parse
scope = scope.between_dates(DateTime.now, ( DateTime.now + 6 ).end_of_day)
when 'custom'
if params[:start_date].blank?
params[:start_date] = DateTime.now.beginning_of_week.strftime('%m/%d/%Y')
end
if params[:end_date].blank?
params[:end_date] = (DateTime.now.end_of_week - 2).strftime('%m/%d/%Y')
end
scope = scope.between_dates(DateTime.strptime(params[:start_date], '%m/%d/%Y'),
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day)
when 'hour'
scope = scope.between_hour_on_day(DateTime.strptime(params[:hour], '%m/%d/%Y %H:
%M'))
when 'today'
scope = scope.between_day(DateTime.now)
end
@events = scope.all
end

38. def index(params)
scope = Event
case params[:timeframe]
when 'tomorrow'
scope = scope.between_day(DateTime.now + 1)
when 'this_week'
scope = scope.between_dates(DateTime.now, ( DateTime.now + 6 ).end_of_day)
when 'custom'
if params[:start_date].blank?
params[:start_date] = DateTime.now.beginning_of_week.strftime('%m/%d/%Y')
end
if params[:end_date].blank?
params[:end_date] = (DateTime.now.end_of_week - 2).strftime('%m/%d/%Y')
end
scope = scope.between_dates(DateTime.strptime(params[:start_date], '%m/%d/%Y'),
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day)
when 'hour'
scope = scope.between_hour_on_day(DateTime.strptime(params[:hour], '%m/%d/%Y %H:
%M'))
when 'today'
scope = scope.between_day(DateTime.now)
end
escopos diferentes
@events = scope.all
end

39. class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => ["at >= ? AND at <= ?", start_date, end_date ] }
}
named_scope :between_hour_on_day, lambda { |start_hour|
end_date = start_hour + 1.hour-1.second
{ :conditions => {:at => start_hour..end_date} }
}
named_scope :between_day, lambda { |date|
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
{ :conditions => {:at => start_date..end_date} }
}
end

40. jeitos diferentes de
fazer a mesma
class Event < ActiveRecord::Base
coisa
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => ["at >= ? AND at <= ?", start_date, end_date ] }
}
named_scope :between_hour_on_day, lambda { |start_hour|
end_date = start_hour + 1.hour-1.second
{ :conditions => {:at => start_hour..end_date} }
}
named_scope :between_day, lambda { |date|
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
{ :conditions => {:at => start_date..end_date} }
}
end

41. class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => ["at >= ? AND at <= ?", start_date, end_date ] }
}
named_scope :between_hour_on_day, lambda { |start_hour|
end_date = start_hour + 1.hour-1.second
{ :conditions => {:at => start_hour..end_date} }
}
mais lógica
named_scope :between_day, lambda { |date|
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
{ :conditions => {:at => start_date..end_date} }
}
end

42. Plano
1. Centralizar lógica de manipulação de datas
2. Unificar named scopes
3. Extrair lógica do Controller
4. Quebrar lógica de timeframes diferentes

43. def index(params)
case params[:timeframe]
when 'tomorrow'
date = DateTime.now + 1
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
when 'this_week'
start_date = DateTime.now
end_date = (DateTime.now + 6 ).end_of_day
when 'custom'
start_date = params[:start_date].blank? ? DateTime.now.beginning_of_week :
DateTime.strptime(params[:start_date], '%m/%d/%Y')
end_date = params[:end_date].blank? ? (DateTime.now.end_of_week - 2) :
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day
when 'hour'
start_date = DateTime.strptime(params[:hour], '%m/%d/%Y %H:%M')
end_date = start_date + 1.hour-1.second
when 'today'
date = DateTime.now
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
end
@events = Event.between_dates(start_date, end_date)
end

44. class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => {:at => start_date..end_date}}
}
end

45. class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => {:at => start_date..end_date}}
}
end
lib/calendar_search_controller.rb | 27 +++++++++++++--------------
lib/event.rb | 13 +------------
spec/event_spec.rb | 37 -------------------------------------
3 files changed, 14 insertions(+), 63 deletions(-)

46. Antes
.
............
ds
0 .49367 secon
Finished in res
13 examp les, 0 failu
class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => {:at => start_date..end_date}}
}
end
lib/calendar_search_controller.rb | 27 +++++++++++++--------------
lib/event.rb | 13 +------------
spec/event_spec.rb | 37 -------------------------------------
3 files changed, 14 insertions(+), 63 deletions(-)

47. Antes Depois
.......
.
............
ds Finished in
0 .49367 secon 0.25355 seco
Finished in res 7 examples, nds
13 examp les, 0 failu 0 failures
class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => {:at => start_date..end_date}}
}
end
lib/calendar_search_controller.rb | 27 +++++++++++++--------------
lib/event.rb | 13 +------------
spec/event_spec.rb | 37 -------------------------------------
3 files changed, 14 insertions(+), 63 deletions(-)

48. class CalendarSearchController
attr_reader :events
def index(params)
timeframe = TimeFrame.for(params[:timeframe], params[:start_date],
params[:end_date], params[:hour])
@events = Event.between_dates(timeframe.start_date, timeframe.end_date)
end
end
mudança nos testes:
it "should create time frame from params and retrieve events" do
timeframe = TimeFrame.new(DateTime.now, DateTime.now)
TimeFrame.should_receive(:for).with('today', 'start', 'end',
'hour').and_return(timeframe)
events = [Event.new, Event.new]
Event.should_receive(:between_dates).with(timeframe.start_date,
timeframe.end_date).and_return(events)
@controller.index(:timeframe => 'today', :start_date => 'start', :end_date =>
'end', :hour => 'hour')
@controller.events.should == events
end

49. class TimeFrame < Struct.new(:start_date, :end_date)
def self.for(type, start_date, end_date, hour)
case type
when 'tomorrow'
date = DateTime.now + 1
TimeFrame.new(date.at_beginning_of_day, date.end_of_day)
when 'this_week'
TimeFrame.new(DateTime.now, (DateTime.now + 6 ).end_of_day)
when 'custom'
start_date = start_date.blank? ? DateTime.now.beginning_of_week :
DateTime.strptime(start_date, '%m/%d/%Y')
end_date = end_date.blank? ? (DateTime.now.end_of_week - 2) :
DateTime.strptime(end_date, '%m/%d/%Y').end_of_day
TimeFrame.new(start_date, end_date)
when 'hour'
start_date = DateTime.strptime(hour, '%m/%d/%Y %H:%M')
end_date = start_date + 1.hour-1.second
TimeFrame.new(start_date, end_date)
when 'today'
date = DateTime.now
TimeFrame.new(date.at_beginning_of_day, date.end_of_day)
end
end
end

50. describe TimeFrame do
before do
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
describe "today's event" do
it "should use beginning and end of day" do
timeframe = TimeFrame.for('today', nil, nil, nil)
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
end
...
end

51. describe TimeFrame do
before do
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
describe "today's event" do
it "should use beginning and end of day" do
timeframe = TimeFrame.for('today', nil, nil, nil)
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
Rakefile | 4 ++
end
lib/calendar_search_controller.rb | 24 +---------
...
lib/time_frame.rb | 24 ++++++++++
end
spec/acceptance_tests.rb | 75 +++++++++++++++++++++++++++++++
spec/calendar_search_controller_spec.rb | 75 ++++---------------------------
spec/time_frame_spec.rb | 63 ++++++++++++++++++++++++++
6 files changed, 178 insertions(+), 87 deletions(-)

52. Antes
.......
ds
describe d in 0 .25355 secon
Finishe TimeFrame do es
before les, 0 failur
7 examp do
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
describe "today's event" do
it "should use beginning and end of day" do
timeframe = TimeFrame.for('today', nil, nil, nil)
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
Rakefile | 4 ++
end
lib/calendar_search_controller.rb | 24 +---------
...
lib/time_frame.rb | 24 ++++++++++
end
spec/acceptance_tests.rb | 75 +++++++++++++++++++++++++++++++
spec/calendar_search_controller_spec.rb | 75 ++++---------------------------
spec/time_frame_spec.rb | 63 ++++++++++++++++++++++++++
6 files changed, 178 insertions(+), 87 deletions(-)

53. Antes Depois
........
.......
ds Finished in
describe d in 0 .25355 secon
she TimeFrame do
0.17938 seco
nds
Fini 8 examples,
before les, 0 failures
7 ex amp do
0 failures
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
describe "today's event" do
it "should use beginning and end of day" do
timeframe = TimeFrame.for('today', nil, nil, nil)
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
Rakefile | 4 ++
end
lib/calendar_search_controller.rb | 24 +---------
...
lib/time_frame.rb | 24 ++++++++++
end
spec/acceptance_tests.rb | 75 +++++++++++++++++++++++++++++++
spec/calendar_search_controller_spec.rb | 75 ++++---------------------------
spec/time_frame_spec.rb | 63 ++++++++++++++++++++++++++
6 files changed, 178 insertions(+), 87 deletions(-)

54. class TimeFrame
attr_reader :start_date, :end_date
class Today < TimeFrame
def initialize
date = DateTime.now
@start_date, @end_date = date.at_beginning_of_day, date.end_of_day
end
end
...
end
describe TimeFrame::Today do
it "should use beginning and end of day" do
timeframe = TimeFrame::Today.new
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
...
end

55. class TimeFrame
...
def self.for(type, start_date, end_date, hour)
case type
when 'tomorrow' then Tomorrow.new
when 'this_week' then ThisWeek.new
when 'custom' then Custom.new(start_date, end_date)
when 'hour' then Hour.new(hour)
when 'today' then Today.new
end
end
end
describe TimeFrame::Today do
...
describe "parsing" do
it "should parse today's timeframe" do
TimeFrame.for('today', nil, nil, nil).should
be_an_instance_of(TimeFrame::Today)
end
...
end
end

56. class TimeFrame
...
def self.for(type, start_date, end_date, hour)
case type
when 'tomorrow' then Tomorrow.new
when 'this_week' then ThisWeek.new
when 'custom' then Custom.new(start_date, end_date)
when 'hour' then Hour.new(hour)
when 'today' then Today.new
end
end
end
describe TimeFrame::Today do
...
describe "parsing" do
lib/time_frame.rb | 59 +++++++++++++++++++++++++++++++++-------------
it "should parse today's timeframe" do
spec/time_frame_spec.rb | 44 ++++++++++++++++++++++++++--------
TimeFrame.for('today', nil, nil, nil).should
2 files changed, 75 insertions(+), 28 deletions(-)
be_an_instance_of(TimeFrame::Today)
end
...
end
end

57. class TimeFrame
... Antes
.def .self.for(type, start_date, end_date, hour)
... ...
case type
ds
0 .17938 secon
when 'tomorrow' then Tomorrow.new
Finished in
when les, 0 failures ThisWeek.new
8 examp 'this_week' then
when 'custom' then Custom.new(start_date, end_date)
when 'hour' then Hour.new(hour)
when 'today' then Today.new
end
end
end
describe TimeFrame::Today do
...
describe "parsing" do
lib/time_frame.rb | 59 +++++++++++++++++++++++++++++++++-------------
it "should parse today's timeframe" do
spec/time_frame_spec.rb | 44 ++++++++++++++++++++++++++--------
TimeFrame.for('today', nil, nil, nil).should
2 files changed, 75 insertions(+), 28 deletions(-)
be_an_instance_of(TimeFrame::Today)
end
...
end
end

58. class TimeFrame
... Antes Depois
............
def .self.for(type, start_date, end_date, hour) .
.... ...
case type
ds Finished in
when d in 0 .17938 secon
she 'tomorrow' then Tomorrow.new
0.19023 seco
nds
Fini 13 examples,
when les, 0 failures ThisWeek.new
8 examp 'this_week' then
0 failures
when 'custom' then Custom.new(start_date, end_date)
when 'hour' then Hour.new(hour)
when 'today' then Today.new
end
end
end
describe TimeFrame::Today do
...
describe "parsing" do
lib/time_frame.rb | 59 +++++++++++++++++++++++++++++++++-------------
it "should parse today's timeframe" do
spec/time_frame_spec.rb | 44 ++++++++++++++++++++++++++--------
TimeFrame.for('today', nil, nil, nil).should
2 files changed, 75 insertions(+), 28 deletions(-)
be_an_instance_of(TimeFrame::Today)
end
...
end
end

59. Obrigado!
Danilo Sato - @dtsato
ThoughtWorks
www.dtsato.com

60. sato/kata-refac toring-calendar
http: //github.com/dt
Obrigado!
Danilo Sato - @dtsato
ThoughtWorks
www.dtsato.com