Rspec / SinatraExtension: Solution Suggested by namelessjon

gistfile1.txt

require 'spec_helper'

=begin
Example One - this is working
In this example, the constant (ZZZ) is set in the
Spec, and detected in the target code.
=end

module TestModule
  class TestClass
    def method1
      ZZZ
    end
  end
end

describe TestModule::TestClass do
  it "should recognize the CONSTANT" do
    ZZZ = "HELLO WORLD" unless defined?(ZZZ)
    obj = TestModule::TestClass.new
    obj.method1.should == ZZZ
  end
end

require 'sinatra/base'

=begin
Example Two - this is working now - see Jon's suggestion at
https://groups.google.com/d/topic/sinatrarb/6S2mZJq-QC4/discussion

Now the App code is re-defined in every spec, it sees the Constant 
definition, and it includes the correct helper module.
=end

module Sinatra
  module TestExtension
    module Helper1
      def sayname() "Helper1"; end
    end
    module Helper2
      def sayname() "Helper2"; end
    end
    def self.registered(app)
      app.helpers defined?(UseOne) ? Helper1 : Helper2
    end
  end
end

AppDefinition = <<-EOF
class App < Sinatra::Base
  register Sinatra::TestExtension
end
EOF

describe "App" do
  it "should create a valid object" do
    eval AppDefinition
    obj = App.new
    obj.sayname.should == "Helper2"
  end
  it "should recognize the CONSTANT set in the Spec" do
    UseOne = true
    eval AppDefinition
    obj = App.new
    obj.sayname.should == "Helper1"
  end

end