At
At is a small library provides an at method for all Objects which allows you to access instance variables
on an object as if they were accessors for testing purposes, usually within test setups and teardowns.
Install
Bundler: gem 'at' in group :test
RubyGems: gem install at
TL;DR
Basically, at directly translates this:
value = user.instance_eval { @name }
user.instance_eval { @name = "#{value}!" }into this:
value = user.at.name
user.at.name = "#{value}!"Use Case
lib/user.rb
class User
def initialize(first_name=nil, last_name=nil)
@first_name, @last_name = first_name, last_name
end
def full_name
[@first_name, @last_name].compact.join(" ")
end
endspec/spec_helper.rb
require 'user'
require 'at/setup'spec/user_spec.rb
describe User do
describe '#full_name' do
before :all do
subject.at.first_name = 'John'
subject.at.last_name = 'Doe'
end
it 'should output the full name correctly' do
subject.full_name.should == 'John Doe'
end
end
endCheck out the specs for a better usage example.
FAQ
Why is this named "At"?
Because the at symbol (@) is how an instance variable is declared in Ruby!
What if my class defines an at instance method?
At is included on the Object class, so when your class defines the at instance method, you are actually overwriting
the At#at method. Luckily, the at method is just an alias of the _at method, which you can use instead:
describe Event do
describe "#at" do
let(:event_at) { DateTime.now }
before(:all) { subject._at.at = event_at }
it 'should return the DateTime the Event is happening' do
subject.at.should == event_at
end
end
endHow can I include the at and _at methods on a single object?
Include At to the object's class:
lib/user.rb
class User
def initialize(first_name=nil, last_name=nil)
@first_name, @last_name = first_name, last_name
end
def full_name
[@first_name, @last_name].compact.join(" ")
end
endspec/spec_helper.rb
require 'user'
require 'at'
class User
include At
endspec/user_spec.rb
describe User do
describe '#full_name' do
before :all do
subject.at.first_name = 'John'
subject.at.last_name = 'Doe'
end
it 'should output the full name correctly' do
subject.full_name.should == 'John Doe'
end
end
endHow can I include the at method outside of a test environment?
Same premise as the above answer:
require 'at'
class User
include At
def initialize(first_name=nil, last_name=nil)
@first_name, @last_name = first_name, last_name
end
def full_name
[@first_name, @last_name].compact.join(" ")
end
endHow can I use instance variable delegation without the at method?
Simply use At::InstanceVariableDelegator:
require 'at/instance_variable_delegator'
class Application
class Config
attr_reader :hostname, :port
end
attr_reader :config
def initialize(&block)
@config = Config.new
configure(&block) if block_given?
end
def configure(&block)
raise ArgumentError, 'block must be supplied' unless block_given?
delegator = At::InstanceVariableDelegator.new(@config)
block.call(delegator)
end
end
# Usage:
app = Application.new
app.configure do |c|
c.hostname = 'example.com'
c.port = 8080
end
p app.config.hostname # => 'example.com'
p app.config.port # => 8080Contributing
- Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet
- Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it
- Fork the project
- Start a feature/bugfix branch
- Commit and push until you are happy with your contribution
- Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
- Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.
Copyright
Copyright © 2012-2013 Ryan Scott Lewis ryan@rynet.us.
The MIT License (MIT) - See LICENSE for further details.