How do I write an RSpec test to unit-test this interesting metaprogramming code?
- by Kyle Kaitan
Here's some simple code that, for each argument specified, will add specific get/set methods named after that argument. If you write attr_option :foo, :bar, then you will see #foo/foo= and #bar/bar= instance methods on Config:
module Configurator
class Config
def initialize()
@options = {}
end
def self.attr_option(*args)
args.each do |a|
if not self.method_defined?(a)
define_method "#{a}" do
@options[:"#{a}"] ||= {}
end
define_method "#{a}=" do |v|
@options[:"#{a}"] = v
end
else
throw Exception.new("already have attr_option for #{a}")
end
end
end
end
end
So far, so good. I want to write some RSpec tests to verify this code is actually doing what it's supposed to. But there's a problem! If I invoke attr_option :foo in one of the test methods, that method is now forever defined in Config. So a subsequent test will fail when it shouldn't, because foo is already defined:
it "should support a specified option" do
c = Configurator::Config
c.attr_option :foo
# ...
end
it "should support multiple options" do
c = Configurator::Config
c.attr_option :foo, :bar, :baz # Error! :foo already defined
# by a previous test.
# ...
end
Is there a way I can give each test an anonymous "clone" of the Config class which is independent of the others?
