Implement Kernel#<=> with specs (fixes #361)

Author: adambeynon

corelib/kernel.rb

@@ -20,6 +20,16 @@ def ===(other)
     `#{self} == other`
   end
 
+  def <=>(other)
+    %x{
+      if (#{self == other}) {
+        return 0;
+      }
+
+      return nil;
+    }
+  end
+
   def method(name)
     %x{
       var recv = #{self},

spec/rubyspec/core/kernel/comparison_spec.rb

@@ -0,0 +1,15 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "1.9" do
+  describe "Kernel#<=>" do
+    it "returns 0 if self" do
+      obj = Object.new
+      (obj.<=>(obj)).should == 0
+    end
+
+    it "returns nil if self is not == to the argument" do
+      obj = Object.new
+      (obj.<=>(3.14)).should be_nil
+    end
+  end
+end