Refactoring at Large

Refactoring at Large Danilo Sato - @dtsato ThoughtWorks www.dtsato.com

My Plan for Today + • “Inside out” approach • Show me Code (Java) • Strategies and Objectives • Refactoring Ruby/Rails - • Larger refactorings

Why do we change code?

Why do we change code? • Add features

Why do we change code? • Add features • Fix bugs

Why do we change code? • Add features • Fix bugs • Improve design

Why do we change code? • Add features • Fix bugs • Improve design • Optimization

"Refactoring is a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior."

Refactoring Code

Refactoring Code Extr act Method

Refactoring Code

Refactoring Code Eliminate Duplication

• Extract Method • Move Method • Extract Class • Remove Middle Man • Self Encapsulate Field • Decompose Conditional • ...

Tests! Code Test

Tests! Code Test Eliminate Duplication

Other types... Code Test

Other types... Code Code Test

Other types... Code Code Test Test

Other types... Code Code Test Test Split Responsibility

Other types... Code Test

Other types... Test Code

Other types... Test Code Change Design

Even more...

“Big Picture”

Strategy Mechanics

Coding Kata!

CheckoutControllerTest CheckoutController Order Cart

- 1 2/10/refactoring o.com/blog/2011/ http://www.dtsat / h rough-experiment st rategies-a-walkt - 0 9/01/refactoring http://paulh ammant.com/2011/ experiment CheckoutControllerTest CheckoutController Order Cart

public class CheckoutControllerTest { private CheckoutController checkoutController; private Cart cart = new Cart(); // could as easily be a mock private Order order = new Order(); // could as easily be a mock private ModelMap model = new ModelMap(); @Before public void setup() { checkoutController = new CheckoutController(cart, order); } @Test public void checkout_should_add_an_upsell() { String result = checkoutController.goCheckout(model); assertThat(result, equalTo("checkout")); assertThat(model.toString(), equalTo("{cart=Cart{contents=[[iPad]]}}")); } @Test public void place_order_in_checkout_should_make_an_order() { cart.addTo("dummy"); String result = checkoutController.placeOrder(model); assertThat(result, equalTo("orderPlaced")); assertThat(model.toString(), equalTo("{order=Order{cart=Cart{contents=[[dummy]]}}}")); } }

@Controller public class CheckoutController { private final Cart cart; private final Order order; @Autowired public CheckoutController(Cart cart, Order order) { this.cart = cart; this.order = order; } @RequestMapping("/go/to/checkout/") public String goCheckout(ModelMap model) { cart.addTo(findUpsell(cart)); model.addAttribute("cart", cart); return "checkout"; } @RequestMapping("/place/order") public String placeOrder(ModelMap model) { order.place(cart); model.addAttribute("order", order); return "orderPlaced"; } String findUpsell(Cart cart) { return cart.size() == 0 ? "iPad" : "iPod Nano"; } }

Mechanics t his video on: riment Watch factoring-expe com/dt sato/re p://vimeo. htt

First Attempt... t his video on: riment Watch factoring-expe com/dt sato/re p://vimeo. htt

Strategy t his video on: riment Watch factoring-expe com/dt sato/re p://vimeo. htt

Identify your Objective

Identify your Objective “Active” design

Identify your Objective “Active” design • OO Design

Identify your Objective “Active” design • OO Design • Project direction

Identify your Objective “Active” design • OO Design • Project direction • Architectural decisions

Identify your Objective “Passive” design

Identify your Objective “Passive” design • Bad Smells

Identify your Objective “Passive” design • Bad Smells • Metrics

Identify your Objective “Passive” design • Bad Smells • Metrics • Visualizations

Strategize

Strategize ? ? ?

Strategize

Strategize • Isolate the impact of Change

Strategize • Isolate the impact of Change • Baby Steps

Strategize • Isolate the impact of Change • Baby Steps • Keep the tests green

Strategize • Isolate the impact of Change • Baby Steps • Keep the tests green • Moving backwards before moving forward

CalendarSearchController CalendarSearchController Test Event Event

r dtsato/kata-ref actoring-calenda http ://github.com/ CalendarSearchController CalendarSearchController Test Event Event

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

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

def index(params) scope = Event case params[:timeframe] when 'tomorrow' scope = scope.between_day(DateTime.now + 1) when 'this_week' string parsing 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

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 multiple named scopes @events = scope.all end

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

different ways to do the same class Event < ActiveRecord::Base thing 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

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} } } more logic 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

Objectives Active: • Isolate unit tests from the database Passive: • Deal with bad smells

Strategizing 1. Centralize date manipulation logic 2. Unify named scopes 3. Extract logic from Controller 4. Break timeframe into separate pieces

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

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

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(-)

Before . ............ 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(-)

Before ....... After . ............ 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(-)

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 change to tests: 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

describe "Acceptance tests" do around(:each) do |example| Event.transaction { example.run; raise ActiveRecord::Rollback } end before do @controller = CalendarSearchController.new @today = DateTime.strptime('06/01/2011', '%m/%d/%Y') DateTime.stub!(:now).and_return(@today) end it "should return today's events" do today_events = [Event.create(:at => @today), Event.create(:at => @today)] tomorrow = @today + 1 tomorrow_events = [Event.create(:at => tomorrow), Event.create(:at => tomorrow)] @controller.index(:timeframe => 'today') @controller.events.should == today_events end it "should return tomorrow's events" ... it "should return this week's events" ... it "should return events for specified date range" ... it "should default date range to this business week" ... it "returns events for a specified hour" ... end

describe "Acceptance tests" do around(:each) do |example| After ...... Event.transaction { example.run; raise ActiveRecord::Rollback } end Finished in 0.24538 seco before do 6 examples, nds 0 failures @controller = CalendarSearchController.new @today = DateTime.strptime('06/01/2011', '%m/%d/%Y') DateTime.stub!(:now).and_return(@today) end it "should return today's events" do today_events = [Event.create(:at => @today), Event.create(:at => @today)] tomorrow = @today + 1 tomorrow_events = [Event.create(:at => tomorrow), Event.create(:at => tomorrow)] @controller.index(:timeframe => 'today') @controller.events.should == today_events end it "should return tomorrow's events" ... it "should return this week's events" ... it "should return events for specified date range" ... it "should default date range to this business week" ... it "returns events for a specified hour" ... end

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

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

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(-)

Before ....... 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(-)

Before ........ After ....... 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(-)

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

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

class TimeFrame ... Before .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 it "should parse today's timeframe" do TimeFrame.for('today', nil, nil, nil).should be_an_instance_of(TimeFrame::Today) end ... end end

class TimeFrame ... Before ............ After 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 it "should parse today's timeframe" do TimeFrame.for('today', nil, nil, nil).should be_an_instance_of(TimeFrame::Today) end ... end end

class TimeFrame ... Before ............ After 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

“Big Picture” • Architectural Changes • Consolidating different approaches • Substituting components/frameworks

“Big Picture”

“Big Picture” Scope Risk Effort Communication

Change

x x x x x x x Change x xx x

x x x x x x x x x xx x Change xxx x xx x

x x xx x x x x x x x x x x xx x Change xxx x xx x

x x xx x x x x x x x x x x xx x Change xxx x xx x xx xx x x xxx xx x

x x x x x x x x xx x x x x x x x x x x x x x xx x x Change xxx x x x xx x x x x xx xx x x x x x xxx xx x x x x x

Change

x x x x x x x Change x xx x

x Prereq x x x x x x Change x xx x

x Prereq x x x Prereq x x x Change x xx x

x Prereq x x x Prereq x x x Change x xx Prereq x

Prereq Prereq Change Prereq

x x Prereq Prereq xx x Change xxx Prereq

x Prereq x Prereq Prereq xx x Prereq Change xxx Prereq

Prereq Prereq Prereq Prereq Change Prereq

Prereq Prereq Prereq Prereq ✔ Change Prereq

Prereq ✔ Prereq Prereq Prereq ✔ Change Prereq

Prereq ✔ Prereq ✔ Prereq Prereq ✔ Change Prereq

Prereq ✔ Prereq ✔ Prereq ✔ Prereq ✔ Change Prereq

Prereq ✔ Prereq ✔ Prereq ✔ Prereq ✔ Change Prereq ✔

Prereq ✔ Prereq ✔ Prereq ✔ Prereq ✔ Change ✔ Prereq ✔

A story APP

A story APP SVC

The truth APP Model View Controller

The truth APP Model View Controller Helper

The truth APP Model View SVC Controller Helper

The truth APP Model View SVC Controller everything is going to break !!! Helper

Transitional Architecture APP Model View Controller SVC Helper

Transitional Architecture • Go: • “Branch by Abstraction” • Migrating from iBatis to Hibernate • Migrating from Velocity/JsTemplate to JRuby on Rails

Transitional Architecture • Go: • “Branch by Abstraction” • Migrating from iBatis to Hibernate • Migrating from Velocity/JsTemplate to JRuby on Rails - 0 11/05/make-large http://continuo usdelivery.com/2 - l y-with-branch-by scale-cha nges-incremental abstraction/

References Books: "Refactoring: Improving the Design of Existing Code" - Martin Fowler, Kent Beck, John Brant, William Opdyke, Don Roberts "Refactoring to Patterns" - Joshua Kerievsky "Working Effectively with Legacy Code" - Michael Feathers "Beheading the Software Beast: Relentless Restructurings with The Mikado Method" - Daniel Brolund, Ola Ellnestam Credits (fotos): http://www.ﬂickr.com/photos/dhammza/2227347832/ http://www.ﬂickr.com/photos/pragdave/173640462/ Links: http://paulhammant.com/2011/09/01/refactoring-experiment http://continuousdelivery.com/2011/05/make-large-scale-changes-incrementally-with- branch-by-abstraction/ Code: https://github.com/dtsato/refactoring_experiment https://github.com/dtsato/kata-refactoring-calendar

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

Refactoring at Large

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