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/io/readline_spec.rb

@@ -0,0 +1,45 @@
+# -*- encoding: utf-8 -*-
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "IO#readline" do
+  before :each do
+    @io = IOSpecs.io_fixture "lines.txt"
+  end
+
+  after :each do
+    @io.close unless @io.closed?
+  end
+
+  it "returns the next line on the stream" do
+    @io.readline.should == "Voici la ligne une.\n"
+    @io.readline.should == "Qui è la linea due.\n"
+  end
+
+  it "goes back to first position after a rewind" do
+    @io.readline.should == "Voici la ligne une.\n"
+    @io.rewind
+    @io.readline.should == "Voici la ligne une.\n"
+  end
+
+  it "returns characters after the position set by #seek" do
+    @io.seek(1)
+    @io.readline.should == "oici la ligne une.\n"
+  end
+
+  it "raises EOFError on end of stream" do
+    IOSpecs.lines.length.times { @io.readline }
+    lambda { @io.readline }.should raise_error(EOFError)
+  end
+
+  it "raises IOError on closed stream" do
+    lambda { IOSpecs.closed_io.readline }.should raise_error(IOError)
+  end
+
+  it "assigns the returned line to $_" do
+    IOSpecs.lines.each do |line|
+      @io.readline
+      $_.should == line
+    end
+  end
+end