ruby--ruby/spec/ruby/core/string/prepend_spec.rb

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