Creates a nested example group named by the submitted attribute, and then generates an example using the submitted block.
# This ... describe Array do its(:size) { should eq(0) } end # ... generates the same runtime structure as this: describe Array do describe "size" do it "should eq(0)" do subject.size.should eq(0) end end end
The attribute can be a Symbol or a String. Given a String with dots, the result is as though you concatenated that String onto the subject in an expression.
describe Person do subject do Person.new.tap do |person| person.phone_numbers << "555-1212" end end its("phone_numbers.first") { should eq("555-1212") } end
When the subject is a Hash, you can refer to the Hash keys by specifying a Symbol or String in an array.
describe "a configuration Hash" do subject do { :max_users => 3, 'admin' => :all_permissions } end its([:max_users]) { should eq(3) } its(['admin']) { should eq(:all_permissions) } # You can still access to its regular methods this way: its(:keys) { should include(:max_users) } its(:count) { should eq(2) } end
# File lib/rspec/core/subject.rb, line 120 def its(attribute, &block) describe(attribute) do example do self.class.class_eval do define_method(:subject) do @_subject ||= if attribute.is_a?(Array) super()[*attribute] else attribute.to_s.split('.').inject(super()) do |target, method| target.send(method) end end end end instance_eval(&block) end end end
Defines an explicit subject for an example group which can then be the implicit receiver (through delegation) of calls to should.
@example
describe CheckingAccount, "with $50" do subject { CheckingAccount.new(:amount => 50, :currency => :USD) } it { should have_a_balance_of(50, :USD) } it { should_not be_overdrawn } end
See +ExampleMethods#should+ for more information about this approach.
# File lib/rspec/core/subject.rb, line 151 def subject(&block) block ? @explicit_subject_block = block : explicit_subject || implicit_subject end
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