From: Tanaka Akira <akr@...17n.org>
Date: 2003-12-05T11:13:38+09:00
Subject: [ruby-dev:22143] Re: IO#read

In article <200311252047.hAPKl0gR004704@sharui.nakada.kanuma.tochigi.jp>,
  nobu.nakada@nifty.ne.jp writes:

> lseek()がエラーになるかならないかの差のようですが、どっちかに合
> わせたいですねぇ。

StringIO とは違うほうに合ったようですね。

require 'test/unit'
require 'stringio'
require 'tempfile'

module TestEOF
  def test_eof_0
    open_file("") {|f|
      assert_equal("", f.read(0))
      assert_equal("", f.read(0))
      assert_equal("", f.read)
      assert_equal(nil, f.read(0))
      assert_equal(nil, f.read(0))
    }
    open_file("") {|f|
      assert_equal(nil, f.read(1))
      assert_equal(nil, f.read)
      assert_equal(nil, f.read(1))
    }
  end

  def test_eof_1
    open_file("a") {|f|
      assert_equal("", f.read(0))
      assert_equal("a", f.read(1))
      assert_equal("" , f.read(0))
      assert_equal("" , f.read(0))
      assert_equal("", f.read)
      assert_equal(nil, f.read(0))
      assert_equal(nil, f.read(0))
    }
    open_file("a") {|f|
      assert_equal("a", f.read(1))
      assert_equal(nil, f.read(1))
    }
    open_file("a") {|f|
      assert_equal("a", f.read(2))
      assert_equal(nil, f.read(1))
      assert_equal(nil, f.read)
      assert_equal(nil, f.read(1))
    }
    open_file("a") {|f|
      assert_equal("a", f.read)
      assert_equal(nil, f.read(1))
      assert_equal(nil, f.read)
      assert_equal(nil, f.read(1))
    }
  end
end

class TestStringIOEOF < Test::Unit::TestCase
  include TestEOF
  def open_file(content)
    f = StringIO.new(content)
    yield f
  end
end

class TestFileEOF < Test::Unit::TestCase
  include TestEOF
  def open_file(content)
    f = Tempfile.new("test-eof")
    f << content
    f.rewind
    yield f
  end
end

class TestPipeEOF < Test::Unit::TestCase
  include TestEOF
  def open_file(content)
    f = IO.popen("echo -n #{content}")
    yield f
  end
end
-- 
[田中 哲][たなか あきら][Tanaka Akira]