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Grow a bonsai, not a shrub

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Kevin Deisz @kddeisz

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No content

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Whose fault?

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the people that built automatic cars Whose fault?

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the people that built automatic cars the people that still rent out manual cars Whose fault?

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the people that built automatic cars the people that still rent out manual cars your fault, for never learning how to drive a manual car even though your friend Greg told you multiple times he would teach you, your mother-in-law told you to pick a time and she would rent a manual car for the weekend and teach you, and your father is more than a little embarrassed that you don’t know how Whose fault?

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None of these

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the people that built automatic cars the people that still rent out manual cars your fault, for never learning how to drive a manual car even though your friend Greg told you multiple times he would teach you, your mother-in-law told you to pick a time and she would rent a manual car for the weekend and teach you, and your father is more than a little embarrassed that you don’t know how Whose fault?

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the people that built automatic cars the people that still rent out manual cars your fault, for never learning how to drive a manual car even though your friend Greg told you multiple times he would teach you, your mother-in-law told you to pick a time and she would rent a manual car for the weekend and teach you, and your father is more than a little embarrassed that you don’t know how Whose fault?

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the people that built automatic cars the people that still rent out manual cars your fault, for never learning how to drive a manual car even though your friend Greg told you multiple times he would teach you, your mother-in-law told you to pick a time and she would rent a manual car for the weekend and teach you, and your father is more than a little embarrassed that you don’t know how Whose fault?

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the people that built automatic cars the people that still rent out manual cars your fault, for never learning how to drive a manual car even though your friend Greg told you multiple times he would teach you, your mother-in-law told you to pick a time and she would rent a manual car for the weekend and teach you, and your father is more than a little embarrassed that you don’t know how Whose fault?

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the people that built automatic cars the people that still rent out manual cars your fault, for never learning how to drive a manual car even though your friend Greg told you multiple times he would teach you, your mother-in-law told you to pick a time and she would rent a manual car for the weekend and teach you, and your father is more than a little embarrassed that you don’t know how Whose fault?

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the people that built automatic cars the people that still rent out manual cars your fault, for never learning how to drive a manual car even though your friend Greg told you multiple times he would teach you, your mother-in-law told you to pick a time and she would rent a manual car for the weekend and teach you, and your father is more than a little embarrassed that you don’t know how Whose fault?

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the people that built automatic cars the people that still rent out manual cars your fault, for never learning how to drive a manual car even though your friend Greg told you multiple times he would teach you, your mother-in-law told you to pick a time and she would rent a manual car for the weekend and teach you, and your father is more than a little embarrassed that you don’t know how a societal failure to standardize Whose fault?

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Code is written by the first engineer that has to understand the problem.

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Code is read by every engineer that has to understand the problem.

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Bad outcomes

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Microservices Bad outcomes

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Microservices Halt and refactor Bad outcomes

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Microservices Halt and refactor Complete rewrite Bad outcomes

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Microservices Halt and refactor Complete rewrite Bad outcomes

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Solutions

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Static Analysis Solutions

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Static Analysis
 Reflection Tests
 Solutions

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Static Analysis
 Reflection Tests
 Strategic Investment
 Solutions

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Static Analysis
 Determine the standards Reflection Tests
 Strategic Investment
 Solutions

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Static Analysis
 Determine the standards Reflection Tests
 Enforce standards on new code Strategic Investment
 Solutions

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Static Analysis
 Determine the standards Reflection Tests
 Enforce standards on new code Strategic Investment
 Enforce standards on old code Solutions

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Static Analysis • Reflection Tests • Strategic Investment

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Static Analysis Static Analysis • Reflection Tests • Strategic Investment Determine the standards

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rubocop Static Analysis • Reflection Tests • Strategic Investment

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rubocop Static Analysis • Reflection Tests • Strategic Investment

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rubocop Static Analysis • Reflection Tests • Strategic Investment

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Bundler Gemspec Layout Lint Metrics rubocop Static Analysis • Reflection Tests • Strategic Investment Naming Performance Rails Security Style

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Metrics rubocop Static Analysis • Reflection Tests • Strategic Investment

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AbcSize BlockLength BlockNesting ClassLength CyclomaticComplexity Metrics Static Analysis • Reflection Tests • Strategic Investment LineLength MethodLength ModuleLength ParameterLists PerceivedComplexity

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reek Static Analysis • Reflection Tests • Strategic Investment

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Attribute Boolean Parameter Class Variable Control Parameter Data Clump Duplicate Method Call Feature Envy Instance Variable Assumption Irresponsible Module Long Parameter List reek Long Yield List Manual Dispatch Missing Safe Method Module Initialize Nested Iterators Nil Check Repeated Conditional Subclassed From Core Class Too Many Constants Too Many Instance Variables Too Many Methods Too Many Statements Uncommunicative Method Name Uncommunicative Module Name Uncommunicative Parameter Name Uncommunicative Variable Name Unused Parameters Unused Private Method Utility Function Static Analysis • Reflection Tests • Strategic Investment

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reek Long Yield List Manual Dispatch Missing Safe Method Module Initialize Nested Iterators Nil Check Repeated Conditional Subclassed From Core Class Too Many Constants Too Many Instance Variables Too Many Methods Too Many Statements Uncommunicative Method Name Uncommunicative Module Name Uncommunicative Parameter Name Uncommunicative Variable Name Unused Parameters Unused Private Method Utility Function Static Analysis • Reflection Tests • Strategic Investment Attribute Boolean Parameter Class Variable Control Parameter Data Clump • Duplicate Method Call Feature Envy Instance Variable Assumption • Irresponsible Module Long Parameter List

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Rules Static Analysis • Reflection Tests • Strategic Investment BlockLength ClassLength LineLength ModuleLength MethodLength Too Many Constants Too Many Methods Too Many Statements AbcSize BlockNesting Cyclomatic Complexity Long Parameter List Long Yield List Nested Iterators ParameterLists Perceived Complexity Feature Envy Too Many Instance Variables Utility Function

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Rules - variance Static Analysis • Reflection Tests • Strategic Investment BlockLength ClassLength LineLength ModuleLength MethodLength Too Many Constants Too Many Methods Too Many Statements

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Rules - complexity Static Analysis • Reflection Tests • Strategic Investment AbcSize BlockNesting Cyclomatic Complexity Long Parameter List Long Yield List Nested Iterators ParameterLists Perceived Complexity

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Rules - design Static Analysis • Reflection Tests • Strategic Investment Feature Envy Too Many Instance Variables Utility Function

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Variance Static Analysis • Reflection Tests • Strategic Investment

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class Event ... def self.in_locations(locations) joins(in_locations_join_sources(locations)) .group(:id) .having(in_locations_match_conditions) end class << self def in_locations_explicit_location_match(locations) ... end def in_locations_join_sources(locations) ... end def in_locations_match_conditions ... end end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... def self.in_locations(locations) Queries::EventsInLocations.new(self, locations).results end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... def self.in_locations(locations) Queries::EventsInLocations.new(self, locations).results end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... def self.in_locations(locations) Queries::EventsInLocations.new(self, locations).results end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... def self.in_locations(locations) Queries::EventsInLocations.new(self, locations).results end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end Static Analysis • Reflection Tests • Strategic Investment

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module Queries class EventsInLocations attr_reader :relation, :locations def initialize(relation, locations) @relation = relation @locations = locations end def results relation.joins(join_sources).group(:id) .having(match_conditions) end private def events @events ||= Event.arel_table end ... end end Static Analysis • Reflection Tests • Strategic Investment

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Complexity Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) case model when Event model.host == self when Photo model.uploader == self || can_admin?(model.event) when Post model.creator == self when Recognition model.creator == self when Rsvp model.user == self || can_admin?(model.event) ... end end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) # rubocop:disable all case model when Event model.host == self when Photo model.uploader == self || can_admin?(model.event) when Post model.creator == self when Recognition model.creator == self when Rsvp model.user == self || can_admin?(model.event) ... end end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) case model when Event model.host == self when Photo model.uploader == self || can_admin?(model.event) when Post model.creator == self when Recognition model.creator == self when Rsvp model.user == self || can_admin?(model.event) ... end end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end Static Analysis • Reflection Tests • Strategic Investment

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module Users class AdminCheck attr_reader :user def initialize(user) @user = user end def can_admin?(model) case model when Event model.host == user when Photo model.uploader == user || can_admin?(model.event) when Post model.creator == user when Recognition model.creator == user ... end end end Static Analysis • Reflection Tests • Strategic Investment

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Design Static Analysis • Reflection Tests • Strategic Investment

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module Users class AdminCheck attr_reader :user def initialize(user) @user = user end def can_admin?(model) case model when Event model.host == user when Photo model.uploader == user || can_admin?(model.event) when Post model.creator == user ... end end end Static Analysis • Reflection Tests • Strategic Investment

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module Users class AdminCheck ... def can_admin?(model) case model when Event model.host == user when Photo model.uploader == user || can_admin?(model.event) when Post model.creator == user ... end end end Static Analysis • Reflection Tests • Strategic Investment

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module Checks refine Event do def admin?(user) host == user end end end module Users class AdminCheck ... using Checks def can_admin?(model) case model when Event model.admin?(user) when Photo model.uploader == user || can_admin?(model.event) when Post model.creator == user ... end end end Static Analysis • Reflection Tests • Strategic Investment

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module Checks refine Event do def admin?(user) host == user end end refine Photo do def admin?(user) uploader == user || event.admin?(user) end end end Static Analysis • Reflection Tests • Strategic Investment module Users class AdminCheck ... using Checks def can_admin?(model) case model when Event model.admin?(user) when Photo model.admin?(user) when Post model.creator == user ... end end end

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module Checks refine Event do def admin?(user) host == user end end refine Photo do def admin?(user) uploader == user || event.admin?(user) end end refine Post do def admin?(user) creator == user end end end Static Analysis • Reflection Tests • Strategic Investment module Users class AdminCheck ... using Checks def can_admin?(model) case model when Event model.admin?(user) when Photo model.admin?(user) when Post model.admin?(user) ... end end end

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module Checks refine Event do def admin?(user) host == user end end refine Photo do def admin?(user) uploader == user || event.admin?(user) end end refine Post do def admin?(user) creator == user end end ... end module Users class AdminCheck ... using Checks def can_admin?(model) model.admin?(user) end end end Static Analysis • Reflection Tests • Strategic Investment

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Extract common behavior Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end module Ext module Query def query(name, constant) scope name, ->(*args) { constant.new(self, *args).results } end end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end module Ext module Query def query(name, constant) scope name, ->(*args) { constant.new(self, *args).results } end end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end module Ext module Query def query(name, constant) scope name, ->(*args) { constant.new(self, *args).results } end end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end module Ext module Query def query(name, constant) scope name, ->(*args) { constant.new(self, *args).results } end end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end module Ext module Query def query(name, constant) scope name, ->(*args) { constant.new(self, *args).results } end end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... extend Ext::Query scope :in_locations, -> (locations) { Queries::EventsInLocations.new(self, locations).results } end module Ext module Query def query(name, constant) scope name, ->(*args) { constant.new(self, *args).results } end end end Static Analysis • Reflection Tests • Strategic Investment

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class Event ... extend Ext::Query query :in_locations, Queries::EventsInLocations end module Ext module Query def query(name, constant) scope name, ->(*args) { constant.new(self, *args).results } end end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end module Ext module Factory def factory(method_name, clazz, delegate: []) define_method(method_name) { clazz.new(self) } return if Array(delegate).empty? public_send(:delegate, *delegate, to: method_name) end end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end module Ext module Factory def factory(method_name, clazz, delegate: []) define_method(method_name) { clazz.new(self) } return if Array(delegate).empty? public_send(:delegate, *delegate, to: method_name) end end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end module Ext module Factory def factory(method_name, clazz, delegate: []) define_method(method_name) { clazz.new(self) } return if Array(delegate).empty? public_send(:delegate, *delegate, to: method_name) end end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end module Ext module Factory def factory(method_name, clazz, delegate: []) define_method(method_name) { clazz.new(self) } return if Array(delegate).empty? public_send(:delegate, *delegate, to: method_name) end end end Static Analysis • Reflection Tests • Strategic Investment

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class User < ApplicationRecord ... def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end module Ext module Factory def factory(method_name, clazz, delegate: []) define_method(method_name) { clazz.new(self) } return if Array(delegate).empty? public_send(:delegate, *delegate, to: method_name) end end end Static Analysis • Reflection Tests • Strategic Investment

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Static Analysis • Reflection Tests • Strategic Investment class User < ApplicationRecord ... extend Ext::Factory def can_admin?(model) Users::AdminCheck.new(self).can_admin?(model) end end module Ext module Factory def factory(method_name, clazz, delegate: []) define_method(method_name) { clazz.new(self) } return if Array(delegate).empty? public_send(:delegate, *delegate, to: method_name) end end end

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class User < ApplicationRecord ... extend Ext::Factory factory :admin_check, Users::AdminCheck, delegate: :can_admin? end module Ext module Factory def factory(method_name, clazz, delegate: []) define_method(method_name) { clazz.new(self) } return if Array(delegate).empty? public_send(:delegate, *delegate, to: method_name) end end end Static Analysis • Reflection Tests • Strategic Investment

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Reflection Tests Static Analysis • Reflection Tests • Strategic Investment Enforce standards on new code

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Reflection tests should always answer a question. Static Analysis • Reflection Tests • Strategic Investment

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What needs to be changed before we can upgrade to the next version of Rails? Static Analysis • Reflection Tests • Strategic Investment

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What needs to be changed before we can upgrade to the next version of Rails? Static Analysis • Reflection Tests • Strategic Investment # Be sure to test this when we upgrade Rails

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What needs to be changed before we can upgrade to the next version of Rails? Static Analysis • Reflection Tests • Strategic Investment # Be sure to test this when we upgrade Rails # Monkey-patching Rails here, so we’ll need to
 # test this when we upgrade

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What needs to be changed before we can upgrade to the next version of Rails? Static Analysis • Reflection Tests • Strategic Investment # Be sure to test this when we upgrade Rails # We can remove this when we upgrade Rails # Monkey-patching Rails here, so we’ll need to
 # test this when we upgrade

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require 'test_helper' class UpgradeTest < ActiveSupport::TestCase LAST_TESTED_VERSION = Gem::Version.new('5.2.1') def self.test(name) version = Gem::Version.new(Rails::VERSION::STRING) super(name) { flunk if version > LAST_TESTED_VERSION } end test 'Comment#as_json' test 'counter_cache and touch on comment' test 'counter_cache and touch on cheer' test 'ApplicationController::make_response!' test 'Buildable::TouchAll' end Static Analysis • Reflection Tests • Strategic Investment

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require 'test_helper' class UpgradeTest < ActiveSupport::TestCase LAST_TESTED_VERSION = Gem::Version.new('5.2.1') def self.test(name) version = Gem::Version.new(Rails::VERSION::STRING) super(name) { flunk if version > LAST_TESTED_VERSION } end test 'Comment#as_json' test 'counter_cache and touch on comment' test 'counter_cache and touch on cheer' test 'ApplicationController::make_response!' test 'Buildable::TouchAll' end Static Analysis • Reflection Tests • Strategic Investment

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require 'test_helper' class UpgradeTest < ActiveSupport::TestCase LAST_TESTED_VERSION = Gem::Version.new('5.2.1') def self.test(name) version = Gem::Version.new(Rails::VERSION::STRING) super(name) { flunk if version > LAST_TESTED_VERSION } end test 'Comment#as_json' test 'counter_cache and touch on comment' test 'counter_cache and touch on cheer' test 'ApplicationController::make_response!' test 'Buildable::TouchAll' end Static Analysis • Reflection Tests • Strategic Investment

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require 'test_helper' class UpgradeTest < ActiveSupport::TestCase LAST_TESTED_VERSION = Gem::Version.new('5.2.1') def self.test(name) version = Gem::Version.new(Rails::VERSION::STRING) super(name) { flunk if version > LAST_TESTED_VERSION } end test 'Comment#as_json' test 'counter_cache and touch on comment' test 'counter_cache and touch on cheer' test 'ApplicationController::make_response!' test 'Buildable::TouchAll' end Static Analysis • Reflection Tests • Strategic Investment

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require 'test_helper' class UpgradeTest < ActiveSupport::TestCase LAST_TESTED_VERSION = Gem::Version.new('5.2.1') def self.test(name) version = Gem::Version.new(Rails::VERSION::STRING) super(name) { flunk if version > LAST_TESTED_VERSION } end test 'Comment#as_json' test 'counter_cache and touch on comment' test 'counter_cache and touch on cheer' test 'ApplicationController::make_response!' test 'Buildable::TouchAll' end Static Analysis • Reflection Tests • Strategic Investment

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When do we split actions out into a different controller? Static Analysis • Reflection Tests • Strategic Investment

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When do we split actions out into a different controller? Static Analysis • Reflection Tests • Strategic Investment # TODO: Split this out to a different controller

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When do we split actions out into a different controller? Static Analysis • Reflection Tests • Strategic Investment # TODO: Split this out to a different controller # TODO: Refactor permissions for this controller

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When do we split actions out into a different controller? Static Analysis • Reflection Tests • Strategic Investment # TODO: Split this out to a different controller # TODO: Share this logic # TODO: Refactor permissions for this controller

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require 'test_helper' Rails.application.eager_load! class ControllerActionsTest < ActiveSupport::TestCase ALLOWED = %w[index show create update destroy].freeze ApplicationController.descendants.each do |controller| test "#{controller.name} only has standard actions" do violations = controller.action_methods - ALLOWED assert_empty violations end end end Static Analysis • Reflection Tests • Strategic Investment

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require 'test_helper' Rails.application.eager_load! class ControllerActionsTest < ActiveSupport::TestCase ALLOWED = %w[index show create update destroy].freeze ApplicationController.descendants.each do |controller| test "#{controller.name} only has standard actions" do violations = controller.action_methods - ALLOWED assert_empty violations end end end Static Analysis • Reflection Tests • Strategic Investment

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require 'test_helper' Rails.application.eager_load! class ControllerActionsTest < ActiveSupport::TestCase ALLOWED = %w[index show create update destroy].freeze ApplicationController.descendants.each do |controller| test "#{controller.name} only has standard actions" do violations = controller.action_methods - ALLOWED assert_empty violations end end end Static Analysis • Reflection Tests • Strategic Investment

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require 'test_helper' Rails.application.eager_load! class ControllerActionsTest < ActiveSupport::TestCase ALLOWED = %w[index show create update destroy].freeze ApplicationController.descendants.each do |controller| test "#{controller.name} only has standard actions" do violations = controller.action_methods - ALLOWED assert_empty violations end end end Static Analysis • Reflection Tests • Strategic Investment

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require 'test_helper' Rails.application.eager_load! class ControllerActionsTest < ActiveSupport::TestCase ALLOWED = %w[index show create update destroy].freeze ApplicationController.descendants.each do |controller| test "#{controller.name} only has standard actions" do violations = controller.action_methods - ALLOWED assert_empty violations end end end Static Analysis • Reflection Tests • Strategic Investment

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Where do we place logic that belongs to ActiveRecord models? Static Analysis • Reflection Tests • Strategic Investment

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Where do we place logic that belongs to ActiveRecord models? Static Analysis • Reflection Tests • Strategic Investment # TODO: Move this into its own object

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Where do we place logic that belongs to ActiveRecord models? Static Analysis • Reflection Tests • Strategic Investment # TODO: Move this into its own object # TODO: Refactor to use new factory system

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Where do we place logic that belongs to ActiveRecord models? Static Analysis • Reflection Tests • Strategic Investment # TODO: Move this into its own object # TODO: Reuse logic from other location # TODO: Refactor to use new factory system

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require 'ripper' class DefList class DefStatement ... end ... def read(filepath) parse(filepath, Ripper.sexp(File.read(filepath))) end private def parse(filepath, node) defs << DefStatement.new(filepath, node) if node[0] == :def node.each do |subnode| parse(filepath, subnode) if subnode.is_a?(Array) end end end Static Analysis • Reflection Tests • Strategic Investment

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require 'ripper' class DefList class DefStatement ... end ... def read(filepath) parse(filepath, Ripper.sexp(File.read(filepath))) end private def parse(filepath, node) defs << DefStatement.new(filepath, node) if node[0] == :def node.each do |subnode| parse(filepath, subnode) if subnode.is_a?(Array) end end end Static Analysis • Reflection Tests • Strategic Investment

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require 'ripper' class DefList class DefStatement ... end ... def read(filepath) parse(filepath, Ripper.sexp(File.read(filepath))) end private def parse(filepath, node) defs << DefStatement.new(filepath, node) if node[0] == :def node.each do |subnode| parse(filepath, subnode) if subnode.is_a?(Array) end end end Static Analysis • Reflection Tests • Strategic Investment

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require 'ripper' class DefList class DefStatement ... end ... def read(filepath) parse(filepath, Ripper.sexp(File.read(filepath))) end private def parse(filepath, node) defs << DefStatement.new(filepath, node) if node[0] == :def node.each do |subnode| parse(filepath, subnode) if subnode.is_a?(Array) end end end Static Analysis • Reflection Tests • Strategic Investment

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Static Analysis • Reflection Tests • Strategic Investment require 'test_helper' class DefTest < ActiveSupport::TestCase test 'no defs in models' do def_list = DefList.from(Dir['app/models/*.rb']) violations = def_list.defs.map(&:to_s) assert_empty violations, <<~MSG Expected #{methods} to be empty. It looks like you defined an instance method on an ActiveRecord model. We prefer to leave AR model declarations to contain only database-level logic (like scopes and associations) and to instead place other logic in delegated objects. Check out `Ext::Factory` and `Ext::Query` for examples. MSG end end

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Static Analysis • Reflection Tests • Strategic Investment require 'test_helper' class DefTest < ActiveSupport::TestCase test 'no defs in models' do def_list = DefList.from(Dir['app/models/*.rb']) violations = def_list.defs.map(&:to_s) assert_empty violations, <<~MSG Expected #{methods} to be empty. It looks like you defined an instance method on an ActiveRecord model. We prefer to leave AR model declarations to contain only database-level logic (like scopes and associations) and to instead place other logic in delegated objects. Check out `Ext::Factory` and `Ext::Query` for examples. MSG end end

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Static Analysis • Reflection Tests • Strategic Investment require 'test_helper' class DefTest < ActiveSupport::TestCase test 'no defs in models' do def_list = DefList.from(Dir['app/models/*.rb']) violations = def_list.defs.map(&:to_s) assert_empty violations, <<~MSG Expected #{methods} to be empty. It looks like you defined an instance method on an ActiveRecord model. We prefer to leave AR model declarations to contain only database-level logic (like scopes and associations) and to instead place other logic in delegated objects. Check out `Ext::Factory` and `Ext::Query` for examples. MSG end end

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Static Analysis • Reflection Tests • Strategic Investment require 'test_helper' class DefTest < ActiveSupport::TestCase test 'no defs in models' do def_list = DefList.from(Dir['app/models/*.rb']) violations = def_list.defs.map(&:to_s) assert_empty violations, <<~MSG Expected #{methods} to be empty. It looks like you defined an instance method on an ActiveRecord model. We prefer to leave AR model declarations to contain only database-level logic (like scopes and associations) and to instead place other logic in delegated objects. Check out `Ext::Factory` and `Ext::Query` for examples. MSG end end

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Static Analysis • Reflection Tests • Strategic Investment require 'test_helper' class DefTest < ActiveSupport::TestCase test 'no defs in models' do def_list = DefList.from(Dir['app/models/*.rb']) violations = def_list.defs.map(&:to_s) assert_empty violations, <<~MSG Expected #{methods} to be empty. It looks like you defined an instance method on an ActiveRecord model. We prefer to leave AR model declarations to contain only database-level logic (like scopes and associations) and to instead place other logic in delegated objects. Check out `Ext::Factory` and `Ext::Query` for examples. MSG end end

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Other reflection tests Static Analysis • Reflection Tests • Strategic Investment

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No multi-line scopes without using a query object Other reflection tests Static Analysis • Reflection Tests • Strategic Investment

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No multi-line scopes without using a query object No associations without automatic inverses or inverse_of specified Other reflection tests Static Analysis • Reflection Tests • Strategic Investment

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No multi-line scopes without using a query object No associations without automatic inverses or inverse_of specified No if statements Other reflection tests Static Analysis • Reflection Tests • Strategic Investment

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This is not heresy. Static Analysis • Reflection Tests • Strategic Investment

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It is heretical to expect code quality to be maintained exclusively through code review. Static Analysis • Reflection Tests • Strategic Investment

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Strategic Investment Static Analysis • Reflection Tests • Strategic Investment Enforce standards on old code

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Passing a linter
 is not a measure of code quality. Static Analysis • Reflection Tests • Strategic Investment

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Passing tests
 is not a measure of code quality. Static Analysis • Reflection Tests • Strategic Investment

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Using design patterns
 is not a measure of code quality. Static Analysis • Reflection Tests • Strategic Investment

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Code is written by the first engineer that has to understand the problem. Static Analysis • Reflection Tests • Strategic Investment

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Code is read by every engineer that has to understand the problem. Static Analysis • Reflection Tests • Strategic Investment

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Readability is the measure of the quality of the code that is going to change. Static Analysis • Reflection Tests • Strategic Investment

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Static Analysis • Reflection Tests • Strategic Investment require 'test_helper' class DefTest < ActiveSupport::TestCase test 'no defs in models' do def_list = DefList.from(Dir['app/models/*.rb']) violations = def_list.defs.map(&:to_s) assert_empty violations, <<~MSG Expected #{methods} to be empty. It looks like you defined an instance method on an ActiveRecord model. We prefer to leave AR model declarations to contain only database-level logic (like scopes and associations) and to instead place other logic in delegated objects. Check out `Ext::Factory` and `Ext::Query` for examples. MSG end end

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Static Analysis • Reflection Tests • Strategic Investment require 'test_helper' class DefTest < ActiveSupport::TestCase LEGACY = File.readlines('legacy.txt').map(&:chomp).freeze test 'no defs in models' do def_list = DefList.from(Dir['app/models/*.rb']) violations = def_list.defs.map(&:to_s) - LEGACY assert_empty violations, <<~MSG Expected #{methods} to be empty. It looks like you defined an instance method on an ActiveRecord model. We prefer to leave AR model declarations to contain only database-level logic (like scopes and associations) and to instead place other logic in delegated objects. Check out `Ext::Factory` and `Ext::Query` for examples. MSG end end

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Static Analysis • Reflection Tests • Strategic Investment require 'test_helper' class DefTest < ActiveSupport::TestCase LEGACY = File.readlines('legacy.txt').map(&:chomp).freeze test 'no more defs in models' do def_list = DefList.from(Dir['app/models/*.rb']) violations = def_list.defs.map(&:to_s) - LEGACY assert_empty violations, <<~MSG Expected #{methods} to be empty. It looks like you defined an instance method on an ActiveRecord model. We prefer to leave AR model declarations to contain only database-level logic (like scopes and associations) and to instead place other logic in delegated objects. Check out `Ext::Factory` and `Ext::Query` for examples. MSG end end

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When code is readable… Static Analysis • Reflection Tests • Strategic Investment

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features are shipped more quickly When code is readable… Static Analysis • Reflection Tests • Strategic Investment

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features are shipped more quickly engineers can onboard more quickly When code is readable… Static Analysis • Reflection Tests • Strategic Investment

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features are shipped more quickly engineers can onboard more quickly bus factor is reduced When code is readable… Static Analysis • Reflection Tests • Strategic Investment

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features are shipped more quickly engineers can onboard more quickly bus factor is reduced patterns become self-evident When code is readable… Static Analysis • Reflection Tests • Strategic Investment

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features are shipped more quickly engineers can onboard more quickly bus factor is reduced patterns become self-evident writing tests is easier When code is readable… Static Analysis • Reflection Tests • Strategic Investment

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Elegance is not a dispensable luxury but a factor that decides between success and failure. - Edsger Dijkstra Static Analysis • Reflection Tests • Strategic Investment

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Object-oriented programming is an exceptionally bad idea which could only have originated in California. - Edsger Dijkstra Static Analysis • Reflection Tests • Strategic Investment

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Static Analysis
 Determine the standards Reflection Tests
 Enforce standards on new code Strategic Investment
 Enforce standards on old code Solutions Static Analysis • Reflection Tests • Strategic Investment

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Static Analysis
 Determine the standards for future code Reflection Tests
 Enforce standards on new code Strategic Investment
 Enforce standards on old code Solutions Static Analysis • Reflection Tests • Strategic Investment

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Static Analysis
 Determine the standards for future code Reflection Tests
 Enforce standards on new code as it changes Strategic Investment
 Enforce standards on old code Solutions Static Analysis • Reflection Tests • Strategic Investment

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Static Analysis
 Determine the standards for future code Reflection Tests
 Enforce standards on new code as it changes Strategic Investment
 Enforce standards on old code if it needs to change Solutions Static Analysis • Reflection Tests • Strategic Investment

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Grow a bonsai, not a shrub github.com/kddeisz/bonsai Kevin Deisz @kddeisz