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path: root/spec/ruby/core/string/delete_prefix_spec.rb
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# -*- encoding: utf-8 -*-
require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes.rb', __FILE__)

ruby_version_is '2.5' do
  describe "String#delete_prefix" do
    it "returns a copy of the string, with the given prefix removed" do
      'hello'.delete_prefix('hell').should == 'o'
      'hello'.delete_prefix('hello').should == ''
    end

    it "returns a copy of the string, when the prefix isn't found" do
      s = 'hello'
      r = s.delete_prefix('hello!')
      r.should_not equal s
      r.should == s
      r = s.delete_prefix('ell')
      r.should_not equal s
      r.should == s
      r = s.delete_prefix('')
      r.should_not equal s
      r.should == s
    end

    it "taints resulting strings when other is tainted" do
      'hello'.taint.delete_prefix('hell').tainted?.should == true
      'hello'.taint.delete_prefix('').tainted?.should == true
    end

    it "doesn't set $~" do
      $~ = nil

      'hello'.delete_prefix('hell')
      $~.should == nil
    end

    it "calls to_str on its argument" do
      o = mock('x')
      o.should_receive(:to_str).and_return 'hell'
      'hello'.delete_prefix(o).should == 'o'
    end

    it "returns a subclass instance when called on a subclass instance" do
      s = StringSpecs::MyString.new('hello')
      s.delete_prefix('hell').should be_an_instance_of(StringSpecs::MyString)
    end
  end

  describe "String#delete_prefix!" do
    it "removes the found prefix" do
      s = 'hello'
      s.delete_prefix!('hell').should equal(s)
      s.should == 'o'
    end

    it "returns nil if no change is made" do
      s = 'hello'
      s.delete_prefix!('ell').should == nil
      s.delete_prefix!('').should == nil
    end

    it "doesn't set $~" do
      $~ = nil

      'hello'.delete_prefix!('hell')
      $~.should == nil
    end

    it "calls to_str on its argument" do
      o = mock('x')
      o.should_receive(:to_str).and_return 'hell'
      'hello'.delete_prefix!(o).should == 'o'
    end

    it "raises a RuntimeError when self is frozen" do
      lambda { 'hello'.freeze.delete_prefix!('hell') }.should raise_error(RuntimeError)
      lambda { 'hello'.freeze.delete_prefix!('') }.should raise_error(RuntimeError)
      lambda { ''.freeze.delete_prefix!('') }.should raise_error(RuntimeError)
    end
  end
end