1 - Look at source code for the current bundle gem version¶ ↑

$ bundle open <gem name>;

Ctl-O = Return back to Netrw dir listing

2 - Get recursive list of dependent gem versions¶ ↑

$ gem lock rails-3.2.13;

2a - Generate PNG of gem dependencies in Gemfile¶ ↑

$ bundle viz;

3 - Rails console¶ ↑

Get nice output in console (YAML output of last command)

> y _

Find exact location of a method

> method(:app).source_location
 => ["/Users/doug/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/console/app.rb", 8]

> app.method(:get).source_location
 => ["/Users/doug/.rvm/gems/ruby-2.2.1/gems/actionpack-4.2.1/lib/action_dispatch/testing/integration.rb", 31]

'app' method gives you an integration session instance, so you can use it just like when you’re a normal integration test for Rails.

> app.class
=> ActionDispatch::Integration::Session

Get list of methods associated with asset pipeline

> Rails.application.methods.each do |method| puts method if method =~ /asset/ end;nil

Get asset file contents

https://github.com/sstephenson/sprockets

'find_asset' method (aliased as []) to retrieve an asset from a Sprockets environment.
  > Rails.application.assets.class
   => Sprockets::Environment

Pass it a logical path and you'll get a Sprockets::BundledAsset (Call 'to_s' on the resulting asset to access its contents)
  > Rails.application.assets['spree/frontend/product.js'].to_s

4 - Run functional tests for only 1 controller¶ ↑

ruby -I test test/functional/globes_controller_test.rb;

(The '-I test' adds the test env into the ruby $LOAD_PATH)

5 - Put <% debugger %> tags in '.erb' code¶ ↑

(rdb) info variables
(rdb:1) bt
  If you are in a View and want to see whole callstack, including the Controller, then DELIBERATELY PUT INCORRECT OBJECT NAME in 'erb'