Add in-tree mspec and ruby/spec

* For easier modifications of ruby/spec by MRI developers.
* .gitignore: track changes under spec.
* spec/mspec, spec/rubyspec: add in-tree mspec and ruby/spec.
  These files can therefore be updated like any other file in MRI.
  Instructions are provided in spec/README.
  [Feature #13156] [ruby-core:79246]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58595 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/rubyspec/library/openssl/random/shared/random_bytes.rb

@@ -0,0 +1,29 @@
+require File.expand_path('../../../../../spec_helper', __FILE__)
+require 'openssl'
+
+describe :openssl_random_bytes, shared: true do |cmd|
+  it "generates a random binary string of specified length" do
+    (1..64).each do |idx|
+      bytes = OpenSSL::Random.send(@method, idx)
+      bytes.should be_kind_of(String)
+      bytes.length.should == idx
+    end
+  end
+
+  it "generates different binary strings with subsequent invocations" do
+    # quick and dirty check, but good enough
+    values = []
+    256.times do
+      val = OpenSSL::Random.send(@method, 16)
+      # make sure the random bytes are not repeating
+      values.include?(val).should == false
+      values << val
+    end
+  end
+
+  it "raises ArgumentError on negative arguments" do
+    lambda {
+      OpenSSL::Random.send(@method, -1)
+    }.should raise_error(ArgumentError)
+  end
+end