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/core/enumerable/minmax_spec.rb

@@ -0,0 +1,44 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "Enumerable#minmax" do
+  before :each do
+    @enum = EnumerableSpecs::Numerous.new(6, 4, 5, 10, 8)
+
+    @strs = EnumerableSpecs::Numerous.new("333", "2", "60", "55555", "1010", "111")
+  end
+
+  it "min should return the minimum element" do
+    @enum.minmax.should == [4, 10]
+    @strs.minmax.should == ["1010", "60" ]
+  end
+
+  it "returns [nil, nil] for an empty Enumerable" do
+    EnumerableSpecs::Empty.new.minmax.should == [nil, nil]
+  end
+
+  it "raises an ArgumentError when elements are incomparable" do
+    lambda do
+      EnumerableSpecs::Numerous.new(11,"22").minmax
+    end.should raise_error(ArgumentError)
+    lambda do
+      EnumerableSpecs::Numerous.new(11,12,22,33).minmax{|a, b| nil}
+    end.should raise_error(ArgumentError)
+  end
+
+  it "raises a NoMethodError for elements without #<=>" do
+    lambda do
+      EnumerableSpecs::Numerous.new(BasicObject.new, BasicObject.new).minmax
+    end.should raise_error(NoMethodError)
+  end
+
+  it "returns the minimum when using a block rule" do
+    @enum.minmax {|a,b| b <=> a }.should == [10, 4]
+    @strs.minmax {|a,b| a.length <=> b.length }.should == ["2", "55555"]
+  end
+
+  it "gathers whole arrays as elements when each yields multiple" do
+    multi = EnumerableSpecs::YieldsMulti.new
+    multi.minmax.should == [[1, 2], [6, 7, 8, 9]]
+  end
+end