From: Josh Cheek <josh.cheek@...>
Date: 2010-10-04T14:07:25+09:00
Subject: Re: save only first line from string?

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On Sun, Oct 3, 2010 at 9:19 PM, Terry Michaels <spare@frigidcode.com> wrote:

> Hi. What's the most simple and elegant way to remove all the contents of
> a String except for the first line? (Assume string consist of one line,
> multiple lines, or no lines, and assume that we don't know which OS we
> are on.)
> --
> Posted via http://www.ruby-forum.com/.
>
>
require 'test/unit'

def first_line(string)
  string.gsub( /$[^\Z]*\Z/m , '' )
end


class FirstLineTest < Test::Unit::TestCase

  def test_return_empty_string_when_given_empty_string
    assert_equal "" , first_line("")
  end

  def test_returns_string_when_given_one_line_string_with_no_newline
    string = "abc def ghi"
    assert_equal string , first_line(string.dup)
  end

  def
test_returns_string_without_newline_when_given_one_line_string_with_newline
    string = "abc def ghi\n"
    assert_equal string.chomp , first_line(string.dup)
  end

  def test_returns_first_line_without_newline_when_given_multi_line_string
    string = "abc def ghi\njkl mno pqr\nstu vwx yz"
    assert_equal "abc def ghi" , first_line(string.dup)
  end

  def test_does_not_mutate_original_string
    string = "abc def ghi\njkl mno pqr\nstu vwx yz"
    first_line string
    assert_equal "abc def ghi\njkl mno pqr\nstu vwx yz" , string
  end
end

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