RailsConf 2015 - Breaking Down the Barrier: Demystifying Contributing to Rails

http://confreaks.tv/videos/railsconf2015-breaking-down-the-barrier-demystifying-contributing-to-rails

Contributing to Rails for the first time can be terrifying. In this lab I’ll make contributing to Rails more approachable by going over the contributing guidelines and technical details you need to know. We’ll walk through traversing the source code with tools such as CTags, source_location and TracePoint. Additionally, we’ll create reproduction scripts for reporting issues and learn advanced git commands like bisect and squash. At the end of this session you’ll have the confidence to fix bugs and add features to Ruby on Rails.

Transcript

1. CLONE THE REPO
   Grab a USB or clone the railsconf_scripts repo from
   https://github.com/eileencodes/railsconf_scripts.git
   $ cd railsconf_scripts
   # mac/linux users
   $ bundle install --local
   # windows users not using a linux VM
   $ git checkout windows
   $ bundle install --local
   

   View Slide

2. BREAKING DOWN
   THE
   Demystifying Contributing
   to Ruby on Rails
   BARRIER:
   

   View Slide

3. EILEEN M. UCHITELLE
   Programmer at Basecamp
   ! eileencodes.com
   " @eileencodes
   # @eileencodes
   

   View Slide

4. View Slide

5. Kingston, New York
   

   View Slide

6. Arya
   @aryadog
   

   View Slide

7. PREREQUISITES
   

   View Slide

8. GOALS
   

   View Slide

9. to Rails
   can be INTIMIDATING.
   CONTRIBUTING
   

   View Slide

10. to Rails open source
    can be is INTIMIDATING.
    CONTRIBUTING #
    

    View Slide

11. FORMAT
    

    View Slide

12. CLONE THE REPO
    Grab a USB or clone the railsconf_scripts repo from
    github.com/eileencodes/railsconf_scripts
    $ cd railsconf_scripts/
    # mac/linux users
    $ bundle install --local
    # windows users not using a linux VM
    $ git checkout windows
    $ bundle install --local
    

    View Slide

13. ENVIRONMENT
    REQUIREMENTS
    

    View Slide

14. ENVIRONMENT
    $ Ruby version manager (rbenv, rvm, chruby)
    $ Ruby 2.2.2
    

    View Slide

15. View Slide

16. % Ruby version manager (rbenv, rvm, chruby)
    % Ruby 2.2.2
    $ Databases for Active Record
    $ MySQL
    $ PostgreSQL
    $ SQLite3
    ENVIRONMENT
    

    View Slide

17. % Ruby version manager (rbenv, rvm, chruby)
    % Ruby 2.2.2
    % Databases for Active Record
    % MySQL
    % PostgreSQL
    % SQLite3
    $ Git & a GitHub Account
    ENVIRONMENT
    

    View Slide

18. RUNNING THE
    TEST SUITE
    

    View Slide

19. View Slide

20. RUNNING TESTS
    $ cd actionpack
    $ rake test
    Finished in 3.237796s, 861.0796 runs/
    s, 4508.3137 assertions/s.

    2788 runs, 14597 assertions, 0
    failures, 0 errors, 0 skips
    

    View Slide

21. ACTIVE RECORD
    $ cd activerecord
    $ rake test:sqlite3
    $ rake test:mysql2
    $ rake test:mysql
    $ rake test:postgresql
    

    View Slide

22. $ ruby -Ilib:test path/to/test_file.rb
    RUN A TEST FILE
    

    View Slide

23. $ ruby -Ilib:test path/to/test_file.rb
    -n test_name_of_test
    RUN A SINGLE TEST
    

    View Slide

24. RUN A SINGLE TEST
    $ ARCONN=mysql2 ruby -Ilib:test path/
    to/test_file.rb -n test_name_of_test
    

    View Slide

25. $ bundle exec rake TEST=path/to/
    test_file.rb -n test_name
    RUN A SINGLE TEST
    

    View Slide

26. $ cd activerecord/
    $ rake test:sqlite3
    $ ruby -Ilib:test test/cases/
    reflection_test.rb
    $ ARCONN=mysql2 ruby -Ilib:test test/
    cases/reflection_test.rb -n
    test_columns
    RUNNING TESTS
    

    View Slide

27. GUIDELINES FOR
    OPENING AN ISSUE
    

    View Slide

28. OPENING AN ISSUE
    $ Be clear and include the Rails version
    

    View Slide

29. OPENING AN ISSUE
    % Be clear and include the Rails version
    $ Don’t open security issues on the issues tracker
    

    View Slide

30. security@rubyonrails.org
    

    View Slide

31. OPENING AN ISSUE
    % Be clear and include the Rails version
    % Don’t open security issues on the issues tracker
    $ Don’t open issues that aren’t a bug in Rails
    

    View Slide

32. OPENING AN ISSUE
    % Be clear and include the Rails version
    % Don’t open security issues on the issues tracker
    % Don’t open issues that aren’t a bug in Rails
    $ Don’t open a separate issue if you have a PR
    

    View Slide

33. OPENING AN ISSUE
    % Be clear and include the Rails version
    % Don’t open security issues on the issues tracker
    % Don’t open issues that aren’t a bug in Rails
    % Don’t open a separate issue if you have a PR
    $ Don’t open feature request tickets
    

    View Slide

34. OPENING AN ISSUE
    % Be clear and include the Rails version
    % Don’t open security issues on the issues tracker
    % Don’t open issues that aren’t a bug in Rails
    % Don’t open a separate issue if you have a PR
    % Don’t open feature request tickets
    % Do include a test script or application
    

    View Slide

35. Examples of executable scripts
    github.com/rails/rails/blob/master/
    guides/bug_report_templates
    TEST SCRIPTS
    

    View Slide

36. $ cd railsconf_scripts/
    $ open ar_script_example.rb
    TEST SCRIPTS
    

    View Slide

37. require 'active_record'
    require 'minitest/autorun'
    require 'logger'
    ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
    ActiveRecord::Base.logger = Logger.new(STDOUT)
    ActiveRecord::Schema.define do
    create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    validates_presence_of :name
    end
    class BugTest < Minitest::Test
    def test_assert
    project = Project.create!
    assert_not_operator project, :valid?
    end
    end
    

    View Slide

38. require 'active_record'
    require 'minitest/autorun'
    require 'logger'
    ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
    ActiveRecord::Base.logger = Logger.new(STDOUT)
    ActiveRecord::Schema.define do
    create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    validates_presence_of :name
    end
    class BugTest < Minitest::Test
    def test_assert
    project = Project.create!
    assert_not_operator project, :valid?
    end
    end
    

    View Slide

39. require 'active_record'
    require 'minitest/autorun'
    require 'logger'
    ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
    ActiveRecord::Base.logger = Logger.new(STDOUT)
    ActiveRecord::Schema.define do
    create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    validates_presence_of :name
    end
    class BugTest < Minitest::Test
    def test_assert
    project = Project.create!
    assert_not_operator project, :valid?
    end
    end
    

    View Slide

40. require 'active_record'
    require 'minitest/autorun'
    require 'logger'
    ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
    ActiveRecord::Base.logger = Logger.new(STDOUT)
    ActiveRecord::Schema.define do
    create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    validates_presence_of :name
    end
    class BugTest < Minitest::Test
    def test_assert
    project = Project.create!
    assert_not_operator project, :valid?
    end
    end
    

    View Slide

41. require 'active_record'
    require 'minitest/autorun'
    require 'logger'
    ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
    ActiveRecord::Base.logger = Logger.new(STDOUT)
    ActiveRecord::Schema.define do
    create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    validates_presence_of :name
    end
    class BugTest < Minitest::Test
    def test_assert
    project = Project.create!
    assert_not_operator project, :valid?
    end
    end
    

    View Slide

42. require 'active_record'
    require 'minitest/autorun'
    require 'logger'
    ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
    ActiveRecord::Base.logger = Logger.new(STDOUT)
    ActiveRecord::Schema.define do
    create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    validates_presence_of :name
    end
    class BugTest < Minitest::Test
    def test_assert
    project = Project.create!
    assert_not_operator project, :valid?
    end
    end
    

    View Slide

43. require 'active_record'
    require 'minitest/autorun'
    require 'logger'
    ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
    ActiveRecord::Base.logger = Logger.new(STDOUT)
    ActiveRecord::Schema.define do
    create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    validates_presence_of :name
    end
    class BugTest < Minitest::Test
    def test_assert
    project = Project.create!
    assert_not_operator project, :valid?
    end
    end
    

    View Slide

44. TEST SCRIPTS
    $ cd railsconf_scripts/
    $ bundle exec ruby ar_script_example.rb
    

    View Slide

45. GUIDELINES FOR
    OPENING A
    PULL REQUEST
    

    View Slide

46. OPENING A PR
    $ Open PR’s against master
    

    View Slide

47. OPENING A PR
    % Open PR’s against master
    $ We don’t accept “cosmetic changes”
    

    View Slide

48. OPENING A PR
    % Open PR’s against master
    % We don’t accept “cosmetic changes”
    $ Write clear and descriptive commit messages
    

    View Slide

49. Short (50 chars or less) summary of changes
    More detailed explanatory text, if necessary. Wrap it to
    about 72 characters or so. In some contexts, the first
    line is treated as the subject of an email and the rest
    of the text as the body. The blank line separating the
    summary from the body is critical (unless you omit
    the body entirely); tools like rebase can get confused
    if you run the two together.
    Further paragraphs come after blank lines.
    - Bullet points are okay, too
    - Typically a hyphen or asterisk is used for the
    bullet, preceded by a single space, with blank lines in
    between, but conventions vary here
    

    View Slide

50. OPENING A PR
    % Open PR’s against master
    % We don’t accept “cosmetic changes”
    % Write clear and descriptive commit messages
    $ Be prepared to squash your commits
    

    View Slide

51. OPENING A PR
    % Open PR’s against master
    % We don’t accept “cosmetic changes”
    % Write clear and descriptive commit messages
    % Be prepared to squash your commits
    $ Don’t ping constantly or litter PR’s with +1’s
    

    View Slide

52. View Slide

53. OPENING A PR
    % Open PR’s against master
    % We don’t accept “cosmetic changes”
    % Write clear and descriptive commit messages
    % Be prepared to squash your commits
    % Don’t ping constantly or litter PR’s with +1’s
    $ We <3 documentation PR’s
    

    View Slide

54. commit 02d3a253610eaf9c80587913b366e3fa0f56b71f
    Author: eileencodes
    Date: Sat Oct 4 11:19:37 2014 -0400
    [ci skip] Clarify deletion strategies for collection
    proxies
    For detailed testing of behavior see:
    https://gist.github.com/eileencodes/
    5b0a2fe011dcff6203fe
    This shows destroy_all always destroys records and
    fires callbacks.
    It will never use nullify or delete_all
    delete_all's behavior varies greatly based on `hm`
    vs `hm:t` and deletion
    strategy.
    

    View Slide

55. OPENING A PR
    % Open PR’s against master
    % We don’t accept “cosmetic changes”
    % Write clear and descriptive commit messages
    % Be prepared to squash your commits
    % Don’t ping constantly or litter PR’s with +1’s
    % We <3 documentation PR’s
    $ Keep it simple
    

    View Slide

56. OPENING A PR
    % Open PR’s against master
    % We don’t accept “cosmetic changes”
    % Write clear and descriptive commit messages
    % Be prepared to squash your commits
    % Don’t ping constantly or litter PR’s with +1’s
    % We <3 documentation PR’s
    % Keep it simple
    $ Use Benchmark/ips
    

    View Slide

57. $ cd railsconf_scripts/
    $ open benchmark_ips_example.rb
    BENCHMARK/IPS
    

    View Slide

58. # railsconf_scripts/benchmark_ips_example.rb
    require 'benchmark/ips'
    ARRAY = (1..100).to_a
    def slow
    ARRAY.shuffle.first
    end
    def fast
    ARRAY.sample
    end
    Benchmark.ips do |x|
    x.report('slow') { slow }
    x.report('fast') { fast }
    x.compare!
    end
    

    View Slide

59. # railsconf_scripts/benchmark_ips_example.rb
    require 'benchmark/ips'
    ARRAY = (1..100).to_a
    def slow
    ARRAY.shuffle.first
    end
    def fast
    ARRAY.sample
    end
    Benchmark.ips do |x|
    x.report('slow') { slow }
    x.report('fast') { fast }
    x.compare!
    end
    

    View Slide

60. # railsconf_scripts/benchmark_ips_example.rb
    require 'benchmark/ips'
    ARRAY = (1..100).to_a
    def slow
    ARRAY.shuffle.first
    end
    def fast
    ARRAY.sample
    end
    Benchmark.ips do |x|
    x.report('slow') { slow }
    x.report('fast') { fast }
    x.compare!
    end
    

    View Slide

61. # railsconf_scripts/benchmark_ips_example.rb
    require 'benchmark/ips'
    ARRAY = (1..100).to_a
    def slow
    ARRAY.shuffle.first
    end
    def fast
    ARRAY.sample
    end
    Benchmark.ips do |x|
    x.report('slow') { slow }
    x.report('fast') { fast }
    x.compare!
    end
    

    View Slide

62. $ bundle exec ruby benchmark_ips_example.rb
    Calculating -------------------------------------
    slow 26.801k i/100ms
    fast 131.410k i/100ms
    -------------------------------------------------
    slow 343.594k (± 5.4%) i/s -
    1.715M
    fast 6.348M (±11.8%) i/s -
    31.276M
    Comparison:
    fast: 6347552.5 i/s
    slow: 343594.2 i/s - 18.47x slower
    

    View Slide

63. $ cd railsconf_scripts/
    $ bundle exec ruby
    BENCHMARK/IPS
    benchmark_ips_example.rb
    

    View Slide

64. OPENING A PR
    % Open PR’s against master
    % We don’t accept “cosmetic changes”
    % Write clear and descriptive commit messages
    % Be prepared to squash your commits
    % Don’t ping constantly or litter PR’s with +1’s
    % We <3 documentation PR’s
    % Keep it simple
    % Use Benchmark/ips
    $ Write tests
    

    View Slide

65. WORKING WITH
    DEPRECATIONS
    

    View Slide

66. # nodoc example from activerecord/lib/active_record/
    reflection.rb:588
    class HasManyReflection < AssociationReflection # :nodoc:
    def initialize(name, scope, options, active_record)
    super(name, scope, options, active_record)
    end
    def macro; :has_many; end
    def collection?; true; end
    end
    

    View Slide

67. # Deprecation from activerecord/lib/active_record/tasks/
    # database_tasks.rb:207
    def load_schema_for(*args)
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
    This method was renamed to `#load_schema` and will
    be removed in the future.
    Use `#load_schema` instead.
    MSG
    load_schema(*args)
    end
    

    View Slide

68. TRAVERSING
    UNFAMILIAR CODE
    

    View Slide

69. View Slide

70. # actionview/lib/action_view/template/error.rb:118
    def source_location
    if line_number
    "on line ##{line_number} of "
    else
    'in '
    end + file_name
    end
    

    View Slide

71. SOURCE LOCATION
    $ cd railsconf_scripts/
    $ open source_location.rb
    

    View Slide

72. class Project < ActiveRecord::Base
    has_many :projects
    end
    class Comment < ActiveRecord::Base
    belongs_to :project
    end
    class BugTest < Minitest::Test
    def test_delete_all
    post = Post.create!(title: "Post title", content: "Lots of content")
    comment = Comment.create!(content: "I am a comment", post_id: post.id)
    assert 1, post.comments.count
    post.comments.delete_all
    assert 0, post.comments.count
    end
    end
    

    View Slide

73. class Project < ActiveRecord::Base
    has_many :projects
    end
    class Comment < ActiveRecord::Base
    belongs_to :project
    end
    class BugTest < Minitest::Test
    def test_delete_all
    post = Post.create!(title: "Post title", content: "Lots of content")
    comment = Comment.create!(content: "I am a comment", post_id: post.id)
    assert 1, post.comments.count
    puts post.comments.method(:delete_all).source_location
    assert 0, post.comments.count
    end
    end
    

    View Slide

74. SOURCE LOCATION
    $ cd railsconf_scripts/
    $ bundle exec ruby source_location.rb
    

    View Slide

75. (0.0ms) begin transaction
    SQL (0.1ms) INSERT INTO "comments" ("content",
    "post_id") VALUES (?, ?) [["content", "I am a
    comment"], ["post_id", 1]]
    (0.0ms) commit transaction
    (0.1ms) SELECT COUNT(*) FROM "comments" WHERE
    "comments"."post_id" = ? [["post_id", 1]]
    .../activerecord/lib/active_record/associations/
    collection_proxy.rb
    442
    (0.0ms) SELECT COUNT(*) FROM "comments" WHERE
    "comments"."post_id" = ? [["post_id", 1]]
    

    View Slide

76. # activerecord/lib/active_record/associations/
    collection_proxy.rb:442
    def delete_all(dependent = nil)
    @association.delete_all(dependent)
    end
    

    View Slide

77. CTags
    # OS X
    $ brew install ctags
    # Debian-based linux
    $ sudo apt-get install exuberant-ctags
    # Red Hat-based linux
    $ sudo yum install ctags
    

    View Slide

78. CTags
    $ cd path/to/rails/
    $ ctags -R .
    

    View Slide

79. CTags
    $ cd path/to/rails/
    $ ctags -R -f .git/tags .
    

    View Slide

80. CTags
    Sublime: github.com/SublimeText/CTags
    TextMate: github.com/textmate/
    ctags.tmbundle
    

    View Slide

81. # .vimrc
    map rt :!ctags --tag-relative --extra=+f -
    Rf.git/tags --exclude=.git,pkg —languages=-
    javascript,sql
    set tags+=.git/tags
    

    View Slide

82. CTags
    $ CTRL + ]
    

    View Slide

83. CTags
    $ :ts
    

    View Slide

84. CTags
    $ :ts
    $ N + ENTER
    

    View Slide

85. View Slide

86. # activerecord/lib/active_record/reflection.rb:314
    def association_primary_key(klass = nil)
    options[:primary_key] ||
    primary_key(klass || self.klass)
    end
    

    View Slide

87. # activerecord/lib/active_record/reflection.rb:314
    def association_primary_key(klass = nil)
    puts caller
    options[:primary_key] ||
    primary_key(klass || self.klass)
    end
    

    View Slide

88. .../through_association.rb:48:in `construct_join_attributes'
    .../has_many_through_association.rb:169:in `through_records_for'
    .../has_many_through_association.rb:180:in `block in delete_through_records'
    .../has_many_through_association.rb:179:in `each'
    .../has_many_through_association.rb:179:in `delete_through_records'
    .../has_many_through_association.rb:154:in `delete_records'
    .../has_many_through_association.rb:124:in `delete_or_nullify_all_records'
    .../collection_association.rb:214:in `delete_all'
    .../collection_proxy.rb:443:in `delete_all’
    ar_test_scripts/ar_rails_test.rb:85:in `'
    

    View Slide

89. .../activerecord/lib/active_record/associations/
    through_association.rb:48:in `block in
    construct_join_attributes’
    

    View Slide

90. def construct_join_attributes(*records)
    ensure_mutable
    if source_reflection.association_primary_key(reflection.klass) ==
    reflection.klass.primary_key
    join_attributes = { source_reflection.name => records }
    else
    join_attributes = {
    source_reflection.foreign_key =>
    records.map { |record|
    record.send(source_reflection.association_primary_key(
    reflection.klass))
    }
    }
    end
    if options[:source_type]
    join_attributes[source_reflection.foreign_type] =
    records.map { |record| record.class.base_class.name }
    [...]
    

    View Slide

91. CALLER
    $ cd railsconf_scripts/
    $ open puts_caller.rb
    

    View Slide

92. ActiveRecord::Schema.define do
    create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    after_create :call_me
    def call_me
    puts "======== i am a callback ========"
    end
    end
    class BugTest < Minitest::Test
    def test_create
    project = Project.create!(name: "whatever")
    end
    end
    

    View Slide

93. create_table :projects do |t|
    t.string :name
    end
    end
    class Project < ActiveRecord::Base
    after_create :call_me
    def call_me
    puts caller
    puts "======== i am a callback ========"
    end
    end
    class BugTest < Minitest::Test
    def test_create
    project = Project.create!(name: "whatever")
    end
    end
    

    View Slide

94. CALLER
    $ bundle exec ruby puts_caller.rb
    

    View Slide

95. .../activesupport/lib/active_support/callbacks.rb:428:in `block in
    make_lambda'
    .../activesupport/lib/active_support/callbacks.rb:229:in `call'
    .../activesupport/lib/active_support/callbacks.rb:229:in `block in
    halting_and_conditional'
    .../activesupport/lib/active_support/callbacks.rb:502:in `call'
    .../activesupport/lib/active_support/callbacks.rb:502:in `block in call'
    .../activesupport/lib/active_support/callbacks.rb:502:in `each'
    .../activesupport/lib/active_support/callbacks.rb:502:in `call'
    .../activesupport/lib/active_support/callbacks.rb:90:in `run_callbacks'
    .../activerecord/lib/active_record/callbacks.rb:305:in `_create_record'
    .../activerecord/lib/active_record/timestamp.rb:57:in `_create_record'
    .../activerecord/lib/active_record/persistence.rb:506:in `create_or_update'
    .../activerecord/lib/active_record/callbacks.rb:301:in `block in
    create_or_update'
    .../activesupport/lib/active_support/callbacks.rb:86:in `run_callbacks'
    .../activerecord/lib/active_record/callbacks.rb:301:in `create_or_update'
    .../activerecord/lib/active_record/persistence.rb:151:in `save!'
    [...]
    

    View Slide

96. .../activesupport/lib/active_support/callbacks.rb:
    428:in `block in make_lambda'
    

    View Slide

97. def make_lambda(filter)
    case filter
    when Symbol
    lambda { |target, _, &blk| target.send filter, &blk }
    when String
    l = eval "lambda { |value| #{filter} }"
    lambda { |target, value| target.instance_exec(value, &l) }
    when Conditionals::Value then filter
    when ::Proc
    if filter.arity > 1
    return lambda { |target, _, &blk|
    raise ArgumentError unless block
    target.instance_exec(target, block, &filter)
    }
    end
    if filter.arity <= 0
    lambda { |target, _| target.instance_exec(&filter) }
    else
    lambda { |target, _| target.instance_exec(target, &filter) }
    [...]
    

    View Slide

98. def test_reject_if_method_without_arguments
    Pirate.accepts_nested_attributes_for :ship,
    reject_if: :new_record?
    pirate = Pirate.new(catchphrase: "Stop wastin' me time")
    pirate.ship_attributes = { name: 'Black Pearl' }
    assert_no_difference('Ship.count') { pirate.save! }
    end
    

    View Slide

99. View Slide

100. def test_reject_if_method_without_arguments
     Pirate.accepts_nested_attributes_for :ship,
     reject_if: :new_record?
     pirate = Pirate.new(catchphrase: "Stop wastin' me time")
     tp = TracePoint.new(:call) do |*args|
     p args
     end
     tp.enable
     pirate.ship_attributes = { name: 'Black Pearl' }
     tp.disable
     assert_no_difference('Ship.count') { pirate.save! }
     end
     

     View Slide

101. def test_reject_if_method_without_arguments
     Pirate.accepts_nested_attributes_for :ship,
     reject_if: :new_record?
     pirate = Pirate.new(catchphrase: "Stop wastin' me time")
     tp = TracePoint.new(:call) do |*args|
     p args
     end
     tp.enable
     pirate.ship_attributes = { name: 'Black Pearl' }
     tp.disable
     assert_no_difference('Ship.count') { pirate.save! }
     end
     

     View Slide

102. def test_reject_if_method_without_arguments
     Pirate.accepts_nested_attributes_for :ship,
     reject_if: :new_record?
     pirate = Pirate.new(catchphrase: "Stop wastin' me time")
     tp = TracePoint.new(:call) do |*args|
     p args
     end
     tp.enable
     pirate.ship_attributes = { name: 'Black Pearl' }
     tp.disable
     assert_no_difference('Ship.count') { pirate.save! }
     end
     

     View Slide

103. def test_reject_if_method_without_arguments
     Pirate.accepts_nested_attributes_for :ship,
     reject_if: :new_record?
     pirate = Pirate.new(catchphrase: "Stop wastin' me time")
     tp = TracePoint.new(:call) do |*args|
     p args
     end
     tp.enable
     pirate.ship_attributes = { name: 'Black Pearl' }
     tp.disable
     assert_no_difference('Ship.count') { pirate.save! }
     end
     

     View Slide

104. def test_reject_if_method_without_arguments
     Pirate.accepts_nested_attributes_for :ship,
     reject_if: :new_record?
     pirate = Pirate.new(catchphrase: "Stop wastin' me time")
     tp = TracePoint.new(:call) do |*args|
     p args
     end
     tp.enable
     pirate.ship_attributes = { name: 'Black Pearl' }
     tp.disable
     assert_no_difference('Ship.count') { pirate.save! }
     end
     

     View Slide

105. `ship_attributes='@.../activerecord/lib/active_record/nested_attributes.rb:347
     `assign_nested_attributes_for_one_to_one_association'@.../activerecord/lib/active_record/
     nested_attributes.rb:382
     `nested_attributes_options'@.../activesupport/lib/active_support/core_ext/class/attribute.rb:106
     `nested_attributes_options'@.../activesupport/lib/active_support/core_ext/class/attribute.rb:86
     `with_indifferent_access'@.../activesupport/lib/active_support/core_ext/hash/indifferent_access.rb:8
     `new_from_hash_copying_default'@.../activesupport/lib/active_support/hash_with_indifferent_access.rb:75
     `initialize'@.../activesupport/lib/active_support/hash_with_indifferent_access.rb:58
     `update'@.../activesupport/lib/active_support/hash_with_indifferent_access.rb:127
     `convert_key'@.../activesupport/lib/active_support/hash_with_indifferent_access.rb:258
     `convert_value'@.../activesupport/lib/active_support/hash_with_indifferent_access.rb:262
     `ship'@.../activerecord/lib/active_record/associations/builder/association.rb:110
     `association'@.../activerecord/lib/active_record/associations.rb:149
     `association_instance_get’@.../activerecord/lib/active_record/associations.rb:189
     `_reflect_on_association'@.../activerecord/lib/active_record/reflection.rb:109
     `_reflections'@.../activesupport/lib/active_support/core_ext/class/attribute.rb:86
     `association_class'@.../activerecord/lib/active_record/reflection.rb:435
     `macro'@.../activerecord/lib/active_record/reflection.rb:588
     `require'@.../activesupport/lib/active_support/dependencies.rb:272
     `load_dependency'@.../activesupport/lib/active_support/dependencies.rb:236
     `load?'@.../activesupport/lib/active_support/dependencies.rb:311
     `mechanism'@.../activesupport/lib/active_support/core_ext/module/attribute_accessors.rb:60
     `constant_watch_stack'@.../activesupport/lib/active_support/core_ext/module/attribute_accessors.rb:60
     `watching?'@.../activesupport/lib/active_support/dependencies.rb:99
     `delegate'@.../activesupport/lib/active_support/core_ext/module/delegation.rb:151
     `include?'@/Users/eileen/.rbenv/versions/2.2.0/lib/ruby/2.2.0/set.rb:211
     `initialize'@.../activerecord/lib/active_record/associations/association.rb:24
     `check_validity!'@.../activerecord/lib/active_record/reflection.rb:331
     `check_validity_of_inverse!’@.../activerecord/lib/active_record/reflection.rb:335
     ...
     

     View Slide

106. `ship_attributes='@.../activerecord/lib/active_record/
     nested_attributes.rb:347
     

     View Slide

107. def generate_association_writer(association_name, type)
     generated_association_methods.module_eval <<-eoruby,
     __FILE__, __LINE__ + 1
     if method_defined?(:#{association_name}_attributes=)
     remove_method(:#{association_name}_attributes=)
     end
     def #{association_name}_attributes=(attributes)
     assign_nested_attributes_for_#{type}
     _association(:#{association_name}, attributes)
     end
     eoruby
     end
     

     View Slide

108. TRACE POINT
     $ cd railsconf_scripts/
     $ open trace_point.rb
     

     View Slide

109. class User < ActiveRecord::Base
     has_one :avatar
     accepts_nested_attributes_for :avatar
     end
     class Avatar < ActiveRecord::Base
     belongs_to :user
     end
     class BugTest < Minitest::Test
     def test_trace_point
     user = User.new(name: "My Name")
     user.avatar_attributes = { name: "I am a file name" }
     user.save!
     end
     end
     

     View Slide

110. end
     class Avatar < ActiveRecord::Base
     belongs_to :user
     end
     class BugTest < Minitest::Test
     def test_trace_point
     user = User.new(name: "My Name")
     tp = TracePoint.new(:call) do |*args|
     p args
     end
     user.avatar_attributes = { name: "I am a file name" }
     user.save!
     end
     end
     

     View Slide

111. class Avatar < ActiveRecord::Base
     belongs_to :user
     end
     class BugTest < Minitest::Test
     def test_trace_point
     user = User.new(name: "My Name")
     tp = TracePoint.new(:call) do |*args|
     p args
     end
     tp.enable
     user.avatar_attributes = { name: "I am a file name" }
     tp.disable
     user.save!
     end
     end
     

     View Slide

112. TRACE POINT
     $ bundle exec ruby trace_point.rb
     

     View Slide

113. `avatar_attributes='@.../activerecord/lib/active_record/
     nested_attributes.rb:347
     

     View Slide

114. ADVANCED GIT
     COMMANDS
     

     View Slide

115. GIT
     $ git add .
     $ git commit -m‘Commit message’
     $ git checkout practicing-git
     

     View Slide

116. GIT
     $ git add upstream
     $ git bisect
     $ git reset --[soft|hard]
     $ git rebase -i
     $ git reflog
     

     View Slide

117. GIT REMOTES
     $ cd path/to/rails/
     $ git remote add upstream
     https://github.com/rails/rails.git
     

     View Slide

118. GIT REMOTES
     $ cd path/to/rails/
     $ git remote remove upstream
     $ git remote add upstream
     https://github.com/rails/rails.git
     

     View Slide

119. GIT REMOTES
     $ git pull —-rebase upstream master
     

     View Slide

120. GIT REMOTES
     $ git pull —-rebase upstream master
     $ git push origin master
     

     View Slide

121. GIT BISECT
     $ git bisect
     

     View Slide

122. GIT BISECT
     $ git bisect start
     

     View Slide

123. GIT BISECT
     $ git bisect bad
     $ git bisect good v4.2.rc3
     

     View Slide

124. View Slide

125. Practice
     Git Bisect
     C1 C2 C3 C4 C5 C6 M3 M4
     M0
     

     View Slide

126. AMENDING COMMITS
     $ git commit --amend
     

     View Slide

127. GIT RESET
     $ git reset --soft HEAD@{1}
     

     View Slide

128. GIT RESET
     $ git reset --soft HEAD~N
     

     View Slide

129. GIT RESET
     $ git reset HEAD
     

     View Slide

130. Git Reset
     M1 M2 M3 M4
     M0
     master
     HEAD
     Practice
     

     View Slide

131. GIT REBASE -I
     $ git rebase -i master
     

     View Slide

132. GIT
     

     View Slide

133. 1 pick e92e34f Refactor existing code
     2 pick 80601e8 Oops add in missing code
     3 pick 8d91f76 Remove extra piece I left behind
     4 pick 933bd58 Fix bug reported in #9895
     5 pick 99302ef Clean up changes
     6 pick 5cc3c5a Fix spelling mistake in documentation
     7
     8 # Rebase 0131d99..5cc3c5a onto 0131d99
     9 #
     10 # Commands:
     11 # p, pick = use commit
     12 # r, reword = use commit, but edit the commit message
     13 # e, edit = use commit, but stop for amending
     14 # s, squash = use commit, but meld into previous commit
     15 # f, fixup = like "squash", but discard this commit's log
     16 # x, exec = run command (the rest of the line) using shell
     

     View Slide

134. 1 pick e92e34f Refactor existing code
     2 pick 80601e8 Oops add in missing code
     3 pick 8d91f76 Remove extra piece I left behind
     4 pick 933bd58 Fix bug reported in #9895
     5 pick 99302ef Clean up changes
     6 pick 5cc3c5a Fix spelling mistake in documentation
     7
     8 # Rebase 0131d99..5cc3c5a onto 0131d99
     9 #
     10 # Commands:
     11 # p, pick = use commit
     12 # r, reword = use commit, but edit the commit message
     13 # e, edit = use commit, but stop for amending
     14 # s, squash = use commit, but meld into previous commit
     15 # f, fixup = like "squash", but discard this commit's log
     16 # x, exec = run command (the rest of the line) using shell
     

     View Slide

135. 1 reword e92e34f Refactor existing code
     2 pick 80601e8 Oops add in missing code
     3 pick 8d91f76 Remove extra piece I left behind
     4 pick 933bd58 Fix bug reported in #9895
     5 pick 99302ef Clean up changes
     6 pick 5cc3c5a Fix spelling mistake in documentation
     7
     8 # Rebase 0131d99..5cc3c5a onto 0131d99
     9 #
     10 # Commands:
     11 # p, pick = use commit
     12 # r, reword = use commit, but edit the commit message
     13 # e, edit = use commit, but stop for amending
     14 # s, squash = use commit, but meld into previous commit
     15 # f, fixup = like "squash", but discard this commit's log
     16 # x, exec = run command (the rest of the line) using shell
     

     View Slide

136. 1 reword e92e34f Refactor existing code
     2 pick 80601e8 Oops add in missing code
     3 edit 8d91f76 Remove extra piece I left behind
     4 pick 933bd58 Fix bug reported in #9895
     5 pick 99302ef Clean up changes
     6 pick 5cc3c5a Fix spelling mistake in documentation
     7
     8 # Rebase 0131d99..5cc3c5a onto 0131d99
     9 #
     10 # Commands:
     11 # p, pick = use commit
     12 # r, reword = use commit, but edit the commit message
     13 # e, edit = use commit, but stop for amending
     14 # s, squash = use commit, but meld into previous commit
     15 # f, fixup = like "squash", but discard this commit's log
     16 # x, exec = run command (the rest of the line) using shell
     

     View Slide

137. 1 reword e92e34f Refactor existing code
     2 pick 80601e8 Oops add in missing code
     3 edit 8d91f76 Remove extra piece I left behind
     4 pick 933bd58 Fix bug reported in #9895
     5 squash 99302ef Clean up changes
     6 pick 5cc3c5a Fix spelling mistake in documentation
     7
     8 # Rebase 0131d99..5cc3c5a onto 0131d99
     9 #
     10 # Commands:
     11 # p, pick = use commit
     12 # r, reword = use commit, but edit the commit message
     13 # e, edit = use commit, but stop for amending
     14 # s, squash = use commit, but meld into previous commit
     15 # f, fixup = like "squash", but discard this commit's log
     16 # x, exec = run command (the rest of the line) using shell
     

     View Slide

138. 1 reword e92e34f Refactor existing code
     2 fixup 80601e8 Oops add in missing code
     3 edit 8d91f76 Remove extra piece I left behind
     4 pick 933bd58 Fix bug reported in #9895
     5 squash 99302ef Clean up changes
     6 pick 5cc3c5a Fix spelling mistake in documentation
     7
     8 # Rebase 0131d99..5cc3c5a onto 0131d99
     9 #
     10 # Commands:
     11 # p, pick = use commit
     12 # r, reword = use commit, but edit the commit message
     13 # e, edit = use commit, but stop for amending
     14 # s, squash = use commit, but meld into previous commit
     15 # f, fixup = like "squash", but discard this commit's log
     16 # x, exec = run command (the rest of the line) using shell
     

     View Slide

139. 1 reword e92e34f Refactor existing code
     2 fixup 80601e8 Oops add in missing code
     3 edit 8d91f76 Remove extra piece I left behind
     4 pick 933bd58 Fix bug reported in #9895
     5 squash 99302ef Clean up changes
     6 pick 5cc3c5a Fix spelling mistake in documentation
     7
     8 # Rebase 0131d99..5cc3c5a onto 0131d99
     9 #
     10 # Commands:
     11 # p, pick = use commit
     12 # r, reword = use commit, but edit the commit message
     13 # e, edit = use commit, but stop for amending
     14 # s, squash = use commit, but meld into previous commit
     15 # f, fixup = like "squash", but discard this commit's log
     16 # x, exec = run command (the rest of the line) using shell
     

     View Slide

140. Practice
     M1 M2 M3 M4
     F1 F2 F1 F2
     M0
     Interactive Rebase
     

     View Slide

141. FORCE PUSH
     $ git push -f origin your-branch
     

     View Slide

142. GIT REFLOG
     $ git reflog
     

     View Slide

143. View Slide

144. GIT REFLOG
     $ git reflog
     

     View Slide

145. 628c168 HEAD@{0}: rebase -i (finish): returning to refs/heads/your-branch
     628c168 HEAD@{1}: rebase -i (start): checkout master
     628c168 HEAD@{2}: reset: moving to 628c168
     bc503a1 HEAD@{3}: rebase -i (finish): returning to refs/heads/your-branch
     bc503a1 HEAD@{4}: rebase -i (pick): Add Person model and migration
     1ad2ff2 HEAD@{5}: rebase -i (pick): Improve README section on git reflog
     026457d HEAD@{6}: rebase -i (start): checkout master
     633f620 HEAD@{7}: rebase -i (finish): returning to refs/heads/your-branch
     633f620 HEAD@{8}: rebase -i (pick): Improve README section on git reflog
     19f41a7 HEAD@{9}: commit (amend): Add Person model and migration
     50718b1 HEAD@{10}: rebase -i (edit): Add Person model and migration
     026457d HEAD@{11}: rebase -i (reword): Update README with sections on rebase and
     c8c6000 HEAD@{12}: rebase -i (reword): Update README with sections on rebase and
     628fbd2 HEAD@{13}: rebase -i (squash): Update README description section
     455dab0 HEAD@{14}: rebase -i (fixup): # This is a combination of 2 commits.
     4392779 HEAD@{15}: rebase -i (start): checkout master
     628c168 HEAD@{16}: rebase -i (finish): returning to refs/heads/your-branch
     628c168 HEAD@{17}: rebase -i (start): checkout master
     628c168 HEAD@{18}: rebase -i (finish): returning to refs/heads/your-branch
     628c168 HEAD@{19}: rebase -i (start): checkout master
     628c168 HEAD@{20}: rebase: aborting
     1f935f7 HEAD@{21}: rebase -i (edit): Add Person model and migration
     

     View Slide

146. GIT REFLOG
     $ git reset -—hard 628c168
     

     View Slide

147. 628168
     628168
     50718b
     bc503a1
     C1 C2 C3 C4
     C0
     Git Reflog
     Practice
     

     View Slide

148. FINDING ISSUES
     TO WORK ON
     

     View Slide

149. WHAT TO WORK ON
     $ Test release candidates and that master branch
     

     View Slide

150. WHAT TO WORK ON
     % Test release candidates and that master branch
     $ Fix documentation & work on WIP Guides
     

     View Slide

151. WHAT TO WORK ON
     % Test release candidates and that master branch
     % Fix documentation & work on WIP Guides
     $ Focus on your strengths
     

     View Slide

152. WHAT TO WORK ON
     % Test release candidates and that master branch
     % Fix documentation & work on WIP Guides
     % Focus on your strengths
     $ Work on ActiveJob or WebConsole
     

     View Slide

153. WHAT TO WORK ON
     % Test release candidates and that master branch
     % Fix documentation & work on WIP Guides
     % Focus on your strengths
     % Work on ActiveJob or WebConsole
     $ Review open pull requests
     

     View Slide

154. WHAT TO WORK ON
     % Test release candidates and that master branch
     % Fix documentation & work on WIP Guides
     % Focus on your strengths
     % Work on ActiveJob or WebConsole
     % Review open pull requests
     $ Refactoring methods and tests
     

     View Slide

155. WHAT TO WORK ON
     % Test release candidates and that master branch
     % Fix documentation & work on WIP Guides
     % Focus on your strengths
     % Work on ActiveJob or WebConsole
     % Review open pull requests
     % Refactoring methods and tests
     $ Watch the issues tracker
     

     View Slide

156. WHAT WE COVERED
     % Getting set up
     % Guidelines for opening issues
     % Writing test scripts
     % Guidelines for opening pull requests
     % Git
     % Bisect, Interactive Rebase, Reflog
     % Traversing unfamiliar code
     % source_location, CTags, puts caller, TracePoint
     % Finding issues to work on
     

     View Slide

157. Thank You!
     

     View Slide

158. EILEEN M. UCHITELLE
     Programmer at Basecamp
     ! eileencodes.com
     " @eileencodes
     # @eileencodes
     Slides:
     speakerdeck.com/eileencodes
     

     View Slide