synvertをインストール

[hoge@POGE synvert4.0]$ rbenv exec gem install synvert
Fetching: erubis-2.7.0.gem (100%)
Successfully installed erubis-2.7.0
Fetching: thread_safe-0.3.5.gem (100%)
Successfully installed thread_safe-0.3.5
Fetching: tzinfo-1.2.2.gem (100%)
Successfully installed tzinfo-1.2.2
Fetching: i18n-0.7.0.gem (100%)
Successfully installed i18n-0.7.0
Fetching: activesupport-4.2.4.gem (100%)
Successfully installed activesupport-4.2.4
Fetching: ast-2.1.0.gem (100%)
Successfully installed ast-2.1.0
Fetching: parser-2.2.3.0.gem (100%)
Successfully installed parser-2.2.3.0
Fetching: synvert-core-0.9.0.gem (100%)
Successfully installed synvert-core-0.9.0
Fetching: synvert-0.9.0.gem (100%)
Successfully installed synvert-0.9.0
Parsing documentation for erubis-2.7.0
Installing ri documentation for erubis-2.7.0
Parsing documentation for thread_safe-0.3.5
Installing ri documentation for thread_safe-0.3.5
Parsing documentation for tzinfo-1.2.2
Installing ri documentation for tzinfo-1.2.2
Parsing documentation for i18n-0.7.0
Installing ri documentation for i18n-0.7.0
Parsing documentation for activesupport-4.2.4
Installing ri documentation for activesupport-4.2.4
Parsing documentation for ast-2.1.0
Installing ri documentation for ast-2.1.0
Parsing documentation for parser-2.2.3.0
Installing ri documentation for parser-2.2.3.0
Parsing documentation for synvert-core-0.9.0
Installing ri documentation for synvert-core-0.9.0
Parsing documentation for synvert-0.9.0
Installing ri documentation for synvert-0.9.0
Done installing documentation for erubis, thread_safe, tzinfo, i18n, activesupport, ast, parser, synvert-core, synvert after 38 seconds

synvertを同期する

[hoge@POGE synvert4.0]$ synvert --sync
Current branch master is up to date.
synvert snippets are synced

synvertリストを表示

[hoge@POGE synvert4.0]$ synvert -l
ruby
    keys_each_to_each_key
    map_and_flatten_to_flat_map
    new_safe_navigation_operator
    new_hash_syntax
    new_lambda_syntax
    use_symbol_to_proc
    remove_debug_code
    parallel_assignment_to_sequential_assignment
    block_to_yield
    merge_to_square_brackets
    fast_syntax
    gsub_to_tr
rspec
    its_to_it
    boolean_matcher
    new_config_options
    negative_error_expectation
    stub_and_mock_to_double
    use_new_syntax
    message_expectation
    one_liner_expectation
    explicit_spec_type
    be_close_to_be_within
    should_to_expect
    block_to_expect
    method_stub
    new_hook_scope
    remove_monkey_patches
    pending_to_skip
    collection_matcher
    custom_matcher_new_syntax
factory_girl
    fix_deprecations
    use_new_syntax
    use_short_syntax
rails
    convert_routes_2_3_to_3_0
    upgrade_3_2_to_4_0
    convert_mailers_2_3_to_3_0
    upgrade_3_1_to_3_2
    convert_models_2_3_to_3_0
    convert_views_2_3_to_3_0
    upgrade_3_0_to_3_1
    convert_rails_env
    convert_rails_logger
    upgrade_4_0_to_4_1
    strong_parameters
    upgrade_2_3_to_3_0
    convert_rails_root
    convert_dynamic_finders
default
    check_syntax
will_paginate
    use_new_syntax
shoulda
    fix_deprecations
    use_new_syntax
    use_matcher_syntax

Rails3.2をRails4.0に変換

[hoge@POGE synvert4.0]$ synvert -r rails/upgrade_3_2_to_4_0
===== rails/upgrade_3_2_to_4_0 started =====

Rails4.0の書き方に変換されていく
使った感想、何か改行がいっぱい入ってる。変えて欲しくないものも変わることがある(拡張したコードとか)。コードを分けて参考にする感じだといいかも