RSpecでBDDをしよう

by y@su

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RSpecͰBDDΛ͠Α͏ Rails Developers Meetup 2018 Day3 Yasuhiko Katoh @yatmsu

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ࣗݾ঺հ ■Twitter: @yatmsu ■GitHub: @yatmsu ■ॴଐ: גࣜձࣾυϦίϜ(6/1ʙ) ■Railsྺ: 10೥͙Β͍ • Ver 1.2.x ʙ

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ࠓ೔࿩͢͜ͱ TDD / BDD / RSpec ฉ͍ͯཉ͍͠ਓ෺૾ • एखͷRailsΤϯδχΞ(ब৬͢Δ·Ͱίʔυॻ͍ͯͳ͔ͬͨͱ͔) • RSpec͸୯७ʹςετίʔυΛॻ͘ҝʹ࢖͍ͬͯΔΑͱ͍͏ΤϯδχΞ • ͦΕҎ֎ͷਓͰ΋OKͰ͢ ※ ৭ʑ͋ͬͯRSpecʹ͸͋·Γݴٴ͍ͯ͠ͳ͍Ͱ͢ɾɾ

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TDD

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Test Driven Development ςετۦಈ։ൃ

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TDDͷྺ࢙(؆қ൛) w ೥%%.D$SBDLFO͕%JHJUBM$PNQVUFS1SPHSBNNJOHzΛग़൛ w ιϑτ΢ΣΞςετٕज़ʹ͍ͭͯॻ͔Εͨ࠷ॳͷॻ੶ w ೥୅͸σόοάɾςετɾɾɾ౳ͷ֓೦͕۠ผ͞Ε͍ͯͳ͔ͬͨ࣌୅ w ʮςετʯͱ͍͏༻ޠ͕࢖ΘΕ͍ͯͳ͍ ֘౰͢ΔՕॴͷষ໊͸l1SPHSBN$IFDLPVUz ʙ5%%͋·Γ࠾༻͞Εͳ͔ͬͨظؒʙ w ೥,FOU#FDL͕46OJUΛ։ൃ w ޙͷY6OJUͷݩʹͳΔϢχοτςετϑϨʔϜϫʔΫ w 5%%ͷݪܕͱͳΔϓϩάϥϛϯάख๏΍ςετΛར༻ͨ͠ϦϑΝΫλϦϯάͷߟ͑ํ͕ ஝ੵ͞Ε͍ͯ͘ɻ w %JHJUBM$PNQVUFS1SPHSBNNJOHzͷଘࡏ͕͋ΔͷͰɺ5%%Λൃ໌ͨ͠ͷͰ͸ͳ͘ɺ ʮ5%%Λ࠶ൃݟʯͨ͠ͱݴΘΕ͍ͯΔɻ

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TDDͷྺ࢙(؆қ൛) w ೥,FOU#FDL͕ʮ91ΤΫετϦʔϜɾϓϩάϥϛϯάೖ໳ʯ &YUSFNF 1SPHSBNNJOH&YQMBJOFE&NCSBDF$IBOHF Λग़൛ w ೥,FOU#FDL͕ʮςετۦಈ։ൃೖ໳ʯ 5FTU%SJWFO%FWFMPQNFOUCZ&YBNQMF Λग़൛ w 46OJU࡞੒࣌ʹ࠶ൃݟͨ͠5%%Λߏ੒͢ΔཁૉΛମܥతʹ੔ཧͨ͠಺༰ w ʮ5%%ͷݪయʯͱݺ͹ΕΔॻ੶ ɾɾɾɾɾ

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TDDͷਐΊํ 1. ࠷ॳʹςετίʔυΛ1ͭॻ͘(ςετϑΝʔετ) 2. 1.Λ࣮ߦ͠ɺࣦഊ͢Δ͜ͱΛ֬ೝ͢Δ (Red) 3. 2.ͷςετ͕੒ޭ͢ΔΑ͏ʹ࠷খݶͷϓϩμΫτίʔυΛॻ͘ 4. 3.Λ࣮ߦ͠ɺ੒ޭ͢Δ͜ͱΛ֬ೝ͢Δ (Green) 5. ϓϩμΫτίʔυͷৼΔ෣͍Λม͑ͳ͍Α͏ʹϦϑΝΫλϦϯάΛߦ͏ (Refactor) 6. 1.ʹ໭Δ ͬ͘͟Γݴ͏ͱ͜ͷ։ൃαΠΫϧΛ܁Γฦ͍ͯ͘͠ͷ͕TDDͰ͢ɻ

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3FGBDUPS (3&&/ 3&% TDDͷϚϯτϥ ͜ͷαΠΫϧΛߴ଎Ͱ܁Γฦ͍ͯ͘͠

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࣮ࡍʹ΍ͬͯΈΔ

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࣮૷͍ͨ͠ػೳ • Ϣʔβʔ͕ΞΧ΢ϯτΛ࡞੒͢Δػೳ લఏ৚݅ • ؅ཧը໘ܥͷRailsΞϓϦΛ։ൃதͰ͋Δ • migrationϑΝΠϧ͸লུ(name, emailͱ ͍͏ΧϥϜ͕͋Δusersςʔϒϧ͕͋Δ΋ ͷͱ͠·͢)

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UserϞσϧͷSpecΛ࡞੒ require 'rails_helper' RSpec.describe User, type: :model do end ͜͜·Ͱॻ͍ͨΒςετΛଈ࣮ߦ͠·͢

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࣮ߦ(RED) $ bin/rspec spec/models/user_spec.rb An error occurred while loading ./spec/models/user_spec.rb. Failure/Error: RSpec.describe User, type: :model do NameError: uninitialized constant User No examples found. Finished in 4.46 seconds (files took 8.57 seconds to load) 0 examples, 0 failures, 1 error occurred outside of examples ࣦഊ͢Δ͜ͱΛ֬ೝ

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UserϞσϧΛ࡞੒ class User < ApplicationRecord end ςετΛଈ࣮ߦ͠·͢

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࣮ߦ(Green) $ bin/rspec spec/models/user_spec.rb   No examples found. Finished in 2.69 seconds (files took 7.16 seconds to load) 0 examples, 0 failures ੒ޭ͢Δ͜ͱΛ֬ೝ

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ϦϑΝΫλϦϯά(Refactor) class User < ApplicationRecord end ϞσϧΛ࡞͚ͬͨͩͳͷͰࠓճ͸ແ͠

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࣮ߦ(RED) $ bin/rspec spec/models/user_spec.rb User #register_user trueΛฦ͢͜ͱ (FAILED - 1) Failures: 1) User#register_user trueΛฦ͢͜ͱ Failure/Error: expect(user.register_user('Ϣʔβʔ໊', '[email protected]')).to eq true NoMethodError: undefined method `register_user' for # Finished in 4.49 seconds (files took 10.77 seconds to load) 1 example, 1 failure Failed examples: rspec ./spec/models/user_spec.rb:7 # User#register_user trueΛฦ͢͜ͱ ࣦഊ͢Δ͜ͱΛ֬ೝ

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#register_userϝιουΛ௥Ճ class User < ApplicationRecord def register_user(name, email) true end end ςετΛ௨͢࠷খݶͷίʔυΛ࣮૷͢Δ͜ͱ ࠷খݶͷίʔυͳͷͰ͜ΕͰྑ͍

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࣮ߦ(Green) $ bin/rspec spec/models/user_spec.rb User #register_user trueΛฦ͢͜ͱ Finished in 3.16 seconds (files took 6.98 seconds to load) 1 example, 0 failures ੒ޭ͢Δ͜ͱΛ֬ೝ

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ϦϑΝΫλϦϯά(Refactor) class User < ApplicationRecord def register_user(name, email) true end end ඞཁͳͦ͞͏ɻࠓճ͸ແ͠ɻ

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#register_userͷςετΛ1ͭ௥Ճ require 'rails_helper' RSpec.describe User, type: :model do describe '#register_user' do let(:user) { create :user } it 'trueΛฦ͢͜ͱ' do expect(user.register_user('Ϣʔβʔ໊', '[email protected]')).to eq true end it 'usersςʔϒϧʹσʔλΛ௥Ճ͍ͯ͠Δ͜ͱ' do expect { user.register_user('Ϣʔβʔ໊', '[email protected]') }.to change { described_class.where(name: 'Ϣʔβʔ໊', email: '[email protected]').exists? }.from(false).to(true) end end end ॻ͘ςετ͸΍͸ΓͭͷΈ

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࣮ߦ(RED) $ bin/rspec spec/models/user_spec.rb User #register_user trueΛฦ͢͜ͱ usersςʔϒϧʹσʔλΛ௥Ճ͍ͯ͠Δ͜ͱ (FAILED - 1) Failures: 1) User#register_user usersςʔϒϧʹσʔλΛ௥Ճ͍ͯ͠Δ͜ͱ Failure/Error: expect { user.register_user('Ϣʔβʔ໊', '[email protected]') }.to change { described_class.where(name: 'Ϣʔβʔ໊', email: '[email protected]').exists? }.from(false).to(true) expected `described_class.where(name: 'Ϣʔβʔ໊', email: '[email protected]').exists?` to have changed from false to true, but did not change Finished in 2.95 seconds (files took 9.34 seconds to load) 2 examples, 1 failure Failed examples: rspec ./spec/models/user_spec.rb:11 # User#register_user usersςʔϒϧʹσʔλΛ௥Ճ͍ͯ͠Δ͜ͱ ࣦഊ͢Δ͜ͱΛ֬ೝ

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#register_userϝιουΛߋ৽ class User < ApplicationRecord def register_user(name, email) user = User.new user.name = name user.email = email user.save end end ςετΛ௨͢࠷খݶͷίʔυΛ࣮૷͢Δ͜ͱ ͱʹ͔͘ಈ͘ίʔυΛॻ͚͹͍͍

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࣮ߦ(Green) $ bin/rspec spec/models/user_spec.rb User #register_user trueΛฦ͢͜ͱ usersςʔϒϧʹσʔλΛ௥Ճ͍ͯ͠Δ͜ͱ Finished in 3.5 seconds (files took 8.05 seconds to load) 2 examples, 0 failures ੒ޭ͢Δ͜ͱΛ֬ೝ

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ϦϑΝΫλϦϯά(Refactor) class User < ApplicationRecord def register_user(name, email) user = User.new(name: name, email: email) user.save end end ;ͭ͏ʹOFXͰύϥϝʔλ౉ͤ͹͍͍ΑͶ

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࣮ߦ(Green) $ bin/rspec spec/models/user_spec.rb User #register_user trueΛฦ͢͜ͱ usersςʔϒϧʹσʔλΛ௥Ճ͍ͯ͠Δ͜ͱ Finished in 3.5 seconds (files took 8.31 seconds to load) 2 examples, 0 failures ੒ޭ͢Δ͜ͱΛ֬ೝ 4QFD͕͋Ε͹ϦϑΝΫλϦϯά͠΍͍͢

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TDD͸ιϑτ΢ΣΞςετٕ๏ͷ 1ͭͩͱޡղ͍ͯ͠Δਓ͕ଟ͍͚Ͳɺ ͜͜·Ͱ΍ͬͯΈΔͱTDDͷຊ࣭͸ ʮςετʯͰ͸ແ͍ͱ͍͏ࣄʹؾ෇͘͸ͣɻ ※࣮ࡍʹࣗ෼ͰखΛಈ͔ͯ͠ΈΔͱΑΓཧղग़དྷ·͢ɻ

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Kent Beck “Test-Driven Development: By Example” “ൽ೑ͳ͜ͱʹɺTDD͸ςετٕ๏Ͱ͸ͳ͍ (CunninghamͷެҊ)ɻ TDD͸෼ੳٕ๏Ͱ͋Γɺઃܭٕ๏Ͱ͋Γɺ ࣮ࡍʹ͸։ൃͷ͢΂ͯͷΞΫςΟϏςΟΛ ߏ଄Խ͢Δٕ๏ͳͷͩɻ”

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TDD·ͱΊ • TDDͱ͸ϓϩάϥϜʹඞཁͳ֤ػೳʹ͍ͭͯɺ·ͣ ςετίʔυΛॻ͖(ςετϑΝʔετ)ɺͦͷςετ ͕ಈ࡞͢Δඞཁ࠷௿ݶͳ࣮૷Λߦ͍ɺϦϑΝΫλϦ ϯάΛߦ͏ɾɾͱ͍͏޻ఔΛ୹͍αΠΫϧͰߴ଎ʹ ܁Γฦ͢։ൃελΠϧ • TDDͱ͸ςετٕ๏Ͱ͸ͳ͘ɺઃܭٕ๏Ͱ͋Δɻ

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ͱɺ͍͏Α͏ͳษڧձΛաڈʹ ࣾ಺ษڧձͰ࿩ͨ͜͠ͱ͕͋Γɺ ͦͷ௚ޙʹ࢝·ͬͨࡶஊͰɾɾɾ

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.JOJUFTUͬͯͲ ͏ͳΜͰ͔͢ʁ

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.JOJUFTUͬͯͲ ͏ͳΜͰ͔͢ʁ ςετͷΧόϨο δͬͯԿΛ௒͍͑ͯ Δ΂͖ʁ

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.JOJUFTUͬͯͲ ͏ͳΜͰ͔͢ʁ ϫγͷए͍ࠒ ͸&YDFMʹςετ έʔεΛॻ͍͍ͯͬ ͯɾɾɾ ຊ൪؀ڥͷσʔ λͰͳ͍ͱ࠶ݱ͠ͳ ͍όά͸Ͳ͏΍ͬͯς ετͨ͠Βɾɾɾ ςετͷΧόϨο δͬͯԿΛ௒͍͑ͯ Δ΂͖ʁ ʮςετʯͷ࿩୊͹͔Γʂʂ

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Կނ͜͏ͳͬͯ͠·͏ͷ͔ʁ TDD͸ςετٕ๏Ͱ͸ͳ͍ɻ ͱ͍͏࿩Λͨ͠௚ޙͳͷʹɻ ୭΋Զͷ࿩Λฉ͍ͯͳ͔ͬͨՄೳੑ͕ɾɾɾ

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࿩Λฉ͍͍ͯͳ͔ͬͨΘ͚Ͱ͸ͳ͍(ͱ৴͍ͨ͡) ͦΕ͚ͩʮςετʯͱ͍͏ݴ༿ͷΠϝʔδ͕ڧ͍ͱ͍͏͜ͱ ʮςετʯͱ͍͏ݴ༿Λ஌͍ͬͯΔਓ͸ଟ͍ɻ ʮςετʯͱ͍͏ݴ༿Λฉ͍ͨ࣌఺ͰɺͦΕͧΕ ͕ࢥ͍ඳ͘ʮςετʯʹ͍ͭͯ࿈૝ͯ͠͠·ͬͨ ͷͰ͸ͳ͍͔ɻ ʮTDD = ιϑτ΢ΣΞςετٕ๏ʯ ͱ͍͏ೝࣝʹͳͬͯ͠·ͬͨʁ

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“TDD͸ɺςετͱ͍͏ݴ༿͕࣋ͭχϡΞϯεͷ໰୊ʹ௚໘͍ͯ͠·ͨ͠ɻςε τͱ͍͏୯ޠͱɺͦΕʹ·ͭΘΔޠኮΛ࢖͍ͬͯΔݶΓɺTDD͸ʮٕज़ऀ͕ɺ Ͳ͏࡞Δ͔ʯʹ࢖͏΋ͷͰ͋Δͱ͍͏ઌೖ؍ʹٯΒ͑ͣɺTDDͷਖ਼֬ͳཧղͱ ܒ໤ʹ͸ࢸΒͳ͍ͷͰ͸ͳ͍͔ͱ͍͏໰୊ҙࣝͰ͢ɻ” ൈਮ:: Kent Beck “Test-Driven Development: By Example” ෇࿥C TDDࢧ࣋೿ͷίϛϡχςΟͰ͜ͷ݅͸ٞ࿦ʹͳͬͨɻ ʮTDDʯͰ͸ବ໨ͰޠኮΛม͑ͳ͚Ε͹ͳΒͳ͍ɻ TDDͷTͷ෦෼ʹTestΛ࢖͍ͬͯΔݶΓɺTDD͕ਖ਼͘͠ཧղ ͞ΕΔ͜ͱ͸೉͍͠ɻ ͜͜ͰDanNorth͕ൃݟͨ͠ޠኮ͕ɺɺɺ TDDͱ͍͏ݴ༿๊͕͑Δ໰୊

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Behavior ৼΔ෣͍

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BDD

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Behavior Driven Development ৼ෣ۦಈ։ൃ

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ޠኮͷมߋͱRSpecͷ஀ੜ BTTFSUJPOˠFYQFDUBUJPO UFTUˠFYBNQMF UFTUDBTFˠFYBNQMFHSPVQ UFTUDMBTTˠTQFD w +#FIBWF +BWB ͕։ൃ͞Εͨ %BO/PSUI 5%%ˠ#%%͚ͩͰͳ͘ɺ ؒҧͬͨઌೖ؍Λ༩͑ͳ͍Α͏ ʹɺޠኮΛมߋ 5%%ͷࠒͱ͸ޠኮΛஔ͖׵͑ͨςετϑϨʔϜϫʔΫΛ࡞੒ w 34QFD 3VCZ ͷ஀ੜ΁ %BWF"TUFMTɺ"TMBL)FMMFTZ

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ޠኮ͕มΘΔͱࢥߟͷग़ൃ఺͕มΘΔ ςετ ςετΛॻ͜͏ ςετίʔυ Λॻ͘ ৼΔ෣͍ ৼΔ෣͍Λॻ͜͏ 4QFDΛॻ͘ #%%ͷαΠΫϧ΁ 5%%ͷ৔߹ #%%ͷ৔߹ ˞ॻ͍͍ͯΔϑΝΠϧ͸શ͘ಉ͡

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BDDͷݱঢ় Behaviorͱ͍͏ޠኮͷൃݟʹΑΓɺ BDDͱ͍͏ޡղΛট͘ࣄͷͳ໊͍લ͕͍ͭͨ TDD͸ɺઌೖ؍Ͱޡղ͞ΕΔ͜ͱͳ͘ݱࡏ·Ͱ ਖ਼͘͠ೝࣝ͞Εͯීٴ͍ͯ͠·͢ɻ ΊͰͨ͠ΊͰͨ͠ɻ

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BDDͷݱঢ় ͱɺͳΔ͜ͱ͸ແ͔ͬͨ

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Aslak Hellesoy “Cucumber։ൃऀ” “TDD͸ςετͩͱ͍͏ޡղΛղͨ͘Ίʹ Dan NorthʹΑΓൃ໌͞ΕͨBDD͕ɺ14೥ ܦ͍ͬͨ·ɺਓʑʹςετͩͱޡղ͞Εͯ ͍Δͷ͸ൽ೑ͳ͜ͱͩɻ”

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Կނ͜͏ͳͬͯ͠·ͬͨͷ͔ʁ • BDDͷܒ໤ظ(2003೥ʙ2011೥ࠒ?) • ܒ໤׆ಈ͕ඞཁͩͬͨͷͰ׆ൃͳٞ࿦͕ߦΘΕɺଟ͘ͷ৘ใ͕ྲྀ ௨͍ͯͨ͠ɻ • BDDͷݱࡏ(2018೥) • ࢖༻͍ͯ͠Δݴޠ͸ؔ܎ͳ͘ɺςετίʔυΛॻ͘؀ڥ͕طʹͦ ͜ʹ͋Δͷ͕౰ͨΓલɻ • ʮͳͥςετίʔυΛॻ͘ͷ͔ʁʯͳΜͯߟ͑ͳ͍ɻ ྺ࢙ɾܦҢ౳͸ফ໓ RSpecଞπʔϧ܊͕࢒ͬͨ

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΋ͬͱਂ͘஌Γͨ͘ͳͬͨΒ ෇࿥CΛಡ΋͏

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ͦΕͰ΋BDDΛ΍Δ͜ͱʹ͸ҙຯ͕͋Δ ■ϝϦοτ •͍ͭͰ΋ϦϑΝΫλϦϯάΛߦ͑Δͱ͍͏ʮ҆৺ʯΛಘΒΕΔɻ •ৗʹৼΔ෣͍͕ఆٛ͞Ε͍ͯΔঢ়ଶͳͷͰɺมߋʹର͢Δڪා ͕ແ͘ͳΔɻ •ΠϯλʔϑΣʔεΛҙࣝͨ͠ઃܭ͕ग़དྷΔΑ͏ʹͳΔɻ •ςετϑΝʔετͷ͓͔͛Ͱɺ࠷ॳʹ࢖͍΍͍͢ΠϯλʔϑΣʔ εΛҙࣝͯ͠ઃܭ͢ΔΑ͏ʹͳΔɻ(ػೳ͹͔Γʹҙ͕ࣝ޲͔ Θͳ͍) •ςελϏϦςΟͷߴ͍ϞδϡʔϧΛ࣮૷͢ΔΑ͏ʹͳΔɻ(ૄ݁߹ ͳ࣮૷) •etc….(ଞଟ਺!!

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ͦΕͰ΋BDDΛ΍Δ͜ͱʹ͸ҙຯ͕͋Δ ■σϝϦοτ •ςελϏϦςΟ͕ߴ͍ઃܭ≠ྑ͍ઃܭ ͱ͸ݶΒͳ͍ •ա৒ʹؒ઀૚Λಋೖͯ͠͠·͏Մೳੑ •ʮϢχοτςετΛ͠΍͘͢͢Δࣄʯࣗମ͕໨త Ͱؒ઀૚Λಋೖͯ͠͠·͏͜ͱ΋ •ؒ઀૚͕૿͑Δͱ͍͏͜ͱ͸ɺ؅ཧ͠ͳ͚Ε͹ͳ Βͳ͍ΦϒδΣΫτ͕૿͑ͯ͠·͏ͱ͍͏͜ͱ

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BDDΛ࢝ΊΑ͏ʂ ΋͠ɺBDDΛ΍ͬͨ͜ͱ͕ͳ͍ͱ͍͏ਓ͕͍ͨ Βੋඇ࢝Ί͍ͯͩ͘͞ʂ νʔϜͰͷ։ൃʹ͔͠࢖͑ͳ͍ͱ͍͏΋ͷͰ͸ ͳ͘ݸਓͷٕज़ͳͷͰɺࠓ೔͔ΒͰ΋࢝ΊΔ͜ ͱ͕Ͱ͖·͢ɻ

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͝੩ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ʂ