using shared_context with a block

gistfile1.rb

# The following is an example of how you might use shared content to reduce the
# duplication in https://gist.github.com/1128108. I prefer to avoid examples
# that use `should respond_to`, as it specifies structure rather than behavior.
# I'd recommend specifying something about what happens when the message is
# sent, e.g. subject.some_method.should eq(some_value). That implicitly
# specifies that the object responds to some_method, and provides more useful
# direction/information about how the object should behave.
#
# That said ...

RSpec.configure do |c|
  c.alias_it_should_behave_like_to :can_be_extended_with, "extended with"
  # ^^ use can_be_extended_with in a group and the output will say "extended
  # with"
end

shared_examples MyModule do
  before(:each){ subject.extend(MyModule) }
  it { should respond_to(:some_method) }
end

describe Object do
  extended_with MyModule
end

describe Class do
  extended_with MyModule do
    it { should respond_to(:special_method_for_class) }
  end
end

output.txt

Object
  extended with MyModule
    should respond to #some_method

Class
  extended with MyModule
    should respond to #some_method
    should respond to #special_method_for_class