/core/kernel/gsub_spec.rb

require File.dirname(__FILE__) + '/../../spec_helper'
require File.dirname(__FILE__) + '/fixtures/classes'

describe "Kernel#gsub" do
  it "is a private method" do
    Kernel.should have_private_instance_method(:gsub)
  end

  it "raises a TypeError if $_ is not a String" do
    lambda {
      $_ = 123
      gsub /./, "!"
    }.should raise_error(TypeError)
  end

  it "when matches sets $_ to a new string, leaving the former value unaltered" do
    orig_value = $_ = "hello"
    gsub "ello", "ola"
    $_.should_not equal(orig_value)
    $_.should == "hola"
    orig_value.should == "hello"
  end

  it "returns a string with the same contents as $_ after the operation" do
    $_ = "bye"
    gsub("non-match", "?").should == "bye"

    orig_value = $_ = "bye"
    gsub(/$/, "!").should == "bye!"
  end

  it "accepts Regexps as patterns" do
    $_ = "food"
    gsub /.$/, "l"
    $_.should == "fool"
  end

  it "accepts Strings as patterns, treated literally" do
    $_ = "hello, world."
    gsub ".", "!"
    $_.should == "hello, world!"
  end

  it "accepts objects which respond to #to_str as patterns and treats them as strings" do
    $_ = "hello, world."
    stringlike = mock(".")
    stringlike.should_receive(:to_str).and_return(".")
    gsub stringlike, "!"
    $_.should == "hello, world!"
  end
end

describe "Kernel#gsub with a pattern and replacement" do
  it "accepts strings for replacement" do
    $_ = "hello"
    gsub /./, "."
    $_.should == "....."
  end

  it "accepts objects which respond to #to_str for replacement" do
    o = mock("o")
    o.should_receive(:to_str).and_return("o")
    $_ = "ping"
    gsub "i", o
    $_.should == "pong"
  end

  it "replaces \\1 sequences with the regexp's corresponding capture" do
    $_ = "hello!"
    gsub /(.)(.)/, '\2\1'
    $_.should == "ehll!o"
  end
end

describe "Kernel#gsub with pattern and block" do
  it "acts similarly to using $_.gsub" do
    $_ = "olleh dlrow"
    gsub(/(\w+)/){ $1.reverse }
    $_.should == "hello world"
  end
end

describe "Kernel#gsub!" do
  it "is a private method" do
    Kernel.should have_private_instance_method(:gsub!)
  end
end

describe "Kernel.gsub!" do
  it "needs to be reviewed for spec completeness"
end