Move spec/rubyspec to spec/ruby for consistency

* Other ruby implementations use the spec/ruby directory.
  [Misc #13792] [ruby-core:82287]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59979 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/core/string/prepend_spec.rb

@@ -0,0 +1,64 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes.rb', __FILE__)
+
+describe "String#prepend" do
+  it "prepends the given argument to self and returns self" do
+    str = "world"
+    str.prepend("hello ").should equal(str)
+    str.should == "hello world"
+  end
+
+  it "converts the given argument to a String using to_str" do
+    obj = mock("hello")
+    obj.should_receive(:to_str).and_return("hello")
+    a = " world!".prepend(obj)
+    a.should == "hello world!"
+  end
+
+  it "raises a TypeError if the given argument can't be converted to a String" do
+    lambda { "hello ".prepend [] }.should raise_error(TypeError)
+    lambda { 'hello '.prepend mock('x') }.should raise_error(TypeError)
+  end
+
+  it "raises a RuntimeError when self is frozen" do
+    a = "hello"
+    a.freeze
+
+    lambda { a.prepend "" }.should raise_error(RuntimeError)
+    lambda { a.prepend "test" }.should raise_error(RuntimeError)
+  end
+
+  it "works when given a subclass instance" do
+    a = " world"
+    a.prepend StringSpecs::MyString.new("hello")
+    a.should == "hello world"
+  end
+
+  it "taints self if other is tainted" do
+    x = "x"
+    x.prepend("".taint).tainted?.should be_true
+
+    x = "x"
+    x.prepend("y".taint).tainted?.should be_true
+  end
+
+  ruby_version_is "2.4" do
+    it "takes multiple arguments" do
+      str = " world"
+      str.prepend "he", "", "llo"
+      str.should == "hello world"
+    end
+
+    it "prepends the initial value when given arguments contain 2 self" do
+      str = "hello"
+      str.prepend str, str
+      str.should == "hellohellohello"
+    end
+
+    it "returns self when given no arguments" do
+      str = "hello"
+      str.prepend.should equal(str)
+      str.should == "hello"
+    end
+  end
+end