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/stringio/append_spec.rb

@@ -0,0 +1,84 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "StringIO#<< when passed [Object]" do
+  before :each do
+    @io = StringIO.new("example")
+  end
+
+  it "returns self" do
+    (@io << "just testing").should equal(@io)
+  end
+
+  it "writes the passed argument onto self" do
+    (@io << "just testing")
+    @io.string.should == "just testing"
+    (@io << " and more testing")
+    @io.string.should == "just testing and more testing"
+  end
+
+  it "writes the passed argument at the current position" do
+    @io.pos = 5
+    @io << "<test>"
+    @io.string.should == "examp<test>"
+  end
+
+  it "pads self with \\000 when the current position is after the end" do
+    @io.pos = 15
+    @io << "just testing"
+    @io.string.should == "example\000\000\000\000\000\000\000\000just testing"
+  end
+
+  it "taints self's String when the passed argument is tainted" do
+    (@io << "test".taint)
+    @io.string.tainted?.should be_true
+  end
+
+  it "does not taint self when the passed argument is tainted" do
+    (@io << "test".taint)
+    @io.tainted?.should be_false
+  end
+
+  it "updates self's position" do
+    @io << "test"
+    @io.pos.should eql(4)
+  end
+
+  it "tries to convert the passed argument to a String using #to_s" do
+    obj = mock("to_s")
+    obj.should_receive(:to_s).and_return("Test")
+
+    (@io << obj).string.should == "Testple"
+  end
+end
+
+describe "StringIO#<< when self is not writable" do
+  it "raises an IOError" do
+    io = StringIO.new("test", "r")
+    lambda { io << "test" }.should raise_error(IOError)
+
+    io = StringIO.new("test")
+    io.close_write
+    lambda { io << "test" }.should raise_error(IOError)
+  end
+end
+
+describe "StringIO#<< when in append mode" do
+  before :each do
+    @io = StringIO.new("example", "a")
+  end
+
+  it "appends the passed argument to the end of self, ignoring current position" do
+    (@io << ", just testing")
+    @io.string.should == "example, just testing"
+
+    @io.pos = 3
+    (@io << " and more testing")
+    @io.string.should == "example, just testing and more testing"
+  end
+
+  it "correctly updates self's position" do
+    @io << ", testing"
+    @io.pos.should eql(16)
+  end
+end