Move spec/rubyspec to spec/ruby for consistency

* Other ruby implementations use the spec/ruby directory.
  [Misc #13792] [ruby-core:82287]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59979 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/library/prime/instance_spec.rb

@@ -0,0 +1,21 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require 'prime'
+
+describe "Prime.instance" do
+  it "returns a object representing the set of prime numbers" do
+    Prime.instance.should be_kind_of(Prime)
+  end
+
+  it "returns a object with no obsolete features" do
+    Prime.instance.should_not respond_to(:succ)
+    Prime.instance.should_not respond_to(:next)
+  end
+
+  it "does not complain anything" do
+    lambda { Prime.instance }.should_not complain
+  end
+
+  it "raises a ArgumentError when is called with some arguments" do
+    lambda { Prime.instance(1) }.should raise_error(ArgumentError)
+  end
+end