Merge pull request #279 from monaka/pr-test-for-comparable

Tests for Comparable. Still not all path coverage.

test/t/comparable.rb

+
+assert('<', '15.3.3.2.1') do
+  class Foo
+    include Comparable
+    def <=>(x)
+      0
+    end
+  end
+
+  (Foo.new < Foo.new) == false
+end
+
+assert('<=', '15.3.3.2.2') do
+  class Foo
+    include Comparable
+    def <=>(x)
+      0
+    end
+  end
+
+  (Foo.new <= Foo.new) == true
+end
+
+assert('==', '15.3.3.2.3') do
+  class Foo
+    include Comparable
+    def <=>(x)
+      0
+    end
+  end
+
+  (Foo.new == Foo.new) == true
+end
+
+assert('>', '15.3.3.2.4') do
+  class Foo
+    include Comparable
+    def <=>(x)
+      0
+    end
+  end
+
+  (Foo.new > Foo.new) == false
+end
+
+assert('>=', '15.3.3.2.5') do
+  class Foo
+    include Comparable
+    def <=>(x)
+      0
+    end
+  end
+
+  (Foo.new >= Foo.new) == true
+end
+