Use 'rdf' '>= 2.0.0.beta', '< 3'.

Author: gkellogg

Gemfile

@@ -14,6 +14,6 @@ group :debug do
 end
 
 group :development, :test do
-  gem 'simplecov',  require: false, platform: :mri_21 # Travis doesn't understand 22 yet.
-  gem 'coveralls',  require: false, platform: :mri_21 # Travis doesn't understand 22 yet.
-end
+  gem 'simplecov',  require: false, platform: :mri
+  gem 'coveralls',  require: false, platform: :mri
+end

lib/rdf/spec/version.rb

@@ -14,6 +14,6 @@ def self.to_str() STRING end
 
     ##
     # @return [Array(String, String, String, String)]
-    def self.to_a() [MAJOR, MINOR, TINY, EXTRA].compact end
+    def self.to_a() STRING.split(".") end
   end
 end; end

rdf-spec.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |gem|
 
   gem.required_ruby_version      = '>= 2.0'
   gem.requirements               = []
-  gem.add_runtime_dependency     'rdf',             '>= 1.99', '< 3'
+  gem.add_runtime_dependency     'rdf',             '>= 2.0.0.beta', '< 3'
   gem.add_runtime_dependency     'rdf-isomorphic',  '>= 1.99', '< 3'
   gem.add_runtime_dependency     'rspec',           '~> 3.0'
   gem.add_runtime_dependency     'rspec-its',       '~> 1.0'