named_let
The named_let can be used to make the rspec's output easier to read.
It's wrapper function of let.
named_let(:name){ obj } changes the value which returns 'obj#to_s' and
'obj#inspect' to :name, then output message of 'rspec -format d' be improved more readable.
Usage
add require 'named_let' to your spec_helper.rb or * _spec.rb.
describe 'named_let' do
context 'symbol only' do
named_let(:foo) { Object.new }
it { foo.to_s should == "foo" }
it { foo.inspect.should == "foo" }
end
context 'with label strings' do
named_let(:foo,"label for display"){ Object.new }
it { foo.to_s should == "label for display" }
it { foo.inspect.should == "label for display" }
end
end
You can use name_let! to force the method's invocation before each example, like original let!.
Why named_let?
RSpec uses 'Object#inspect' for generating output message from value of specified by let.
This will generates unexpected output like 'should == #Object:0x2aaaaf8a0870A', it's not human readable.
Now let's use named_let instead of let.The generaed output will be more readable like 'should == "label for display'.
Example
For Example, now writing specs for CanCan like bellow,
require 'spec_helper'
require "cancan/matchers"
describe Ability do
context 'an user' do
let(:user) { Factory.create(:user) }
let(:article) { Factory.create(:article) }
let(:own_article) { Factory.create(:article, :user => user) }
subject { Ability.new(user) }
it { should be_able_to(:read, article) }
it { should be_able_to(:update, own_article) }
end
end
This specs generates outputs is ...
$ bundle exec rspec -c --format d spec/models/ability_spec.rb
Ability
an user
should be able to :read #<Article id: 44, title: "The Test Article 1", body: "This is test article!!", created_at: "2012-02-23 14:19:26", updated_at: "2012-02-23 14:19:26", user_id: nil>
should be able to :update #<Article id: 45, title: "The Test Article 2", body: "This is test article!!", created_at: "2012-02-23 14:19:26", updated_at: "2012-02-23 14:19:26", user_id: 31>
Finished in 0.26158 seconds
2 examples, 0 failures
OMG, It's not human readable. so,let's change let to named_let.
named_let(:article) { Factory.create(:article) }
named_let(:own_article) { Factory.create(:article, :user => user) }
again, execute rspec --format d ...
$ bundle exec rspec -c --format d spec/models/ability_spec.rb
Ability
an user
should be able to :read article
should be able to :update own article
Finished in 0.25375 seconds
2 examples, 0 failures
okay, it's readable!!!
For debugging
If the specs is fail, You will want to know original outputs of 'Object#inspect'. But named_let hides actual outputs of "Object#inspect".
Failures:
1) Ability an user
Failure/Error: it { should_not be_able_to(:update, own_article) }
expected not to be able to :update own article
For debugging spec, if given -d option to rspec command or $DEBUG flag is true,
named_let append orignal result of Object#inspect to returns value.
given -d option, then...
Failures:
1) Ability an user
Failure/Error: it { should_not be_able_to(:update, own_article) }
expected not to be able to :update own article (#<Article id: 113, title: "The Test Article 3", body: "This is test article!!", created_at: "2012-02-24 05:53:17", updated_at: "2012-02-24 05:53:17", user_id: 90>)
NOTE:
Requires ruby-debug to using -d option.
run gem install ruby-debug.
If your Ruby-Runtime is 1.9+, see "https://github.com/mark-moseley/ruby-debug".