ruby--ruby/test/ruby/test_array.rb

require 'test/unit'

class TestArray < Test::Unit::TestCase
  def test_0_literal
    assert_equal([1, 2, 3, 4], [1, 2] + [3, 4])
    assert_equal([1, 2, 1, 2], [1, 2] * 2)
    assert_equal("1:2", [1, 2] * ":")

    assert_equal([1, 2].hash, [1, 2].hash)

    assert_equal([2,3], [1,2,3] & [2,3,4])
    assert_equal([1,2,3,4], [1,2,3] | [2,3,4])
    assert_equal([1,2,3] - [2,3], [1])

    x = [0, 1, 2, 3, 4, 5]
    assert_equal(2, x[2])
    assert_equal([1, 2, 3], x[1..3])
    assert_equal([1, 2, 3], x[1,3])

    x[0, 2] = 10
    assert(x[0] == 10 && x[1] == 2)

    x[0, 0] = -1
    assert(x[0] == -1 && x[1] == 10)

    x[-1, 1] = 20
    assert(x[-1] == 20 && x.pop == 20)
  end

  def test_array_andor_0
    assert_equal([2], ([1,2,3]&[2,4,6]))
    assert_equal([1,2,3,4,6], ([1,2,3]|[2,4,6]))
  end

  def test_compact_0
    a = [nil, 1, nil, nil, 5, nil, nil]
    assert_equal [1, 5], a.compact
    assert_equal [nil, 1, nil, nil, 5, nil, nil], a
    a.compact!
    assert_equal [1, 5], a
  end

  def test_uniq_0
    x = [1, 1, 4, 2, 5, 4, 5, 1, 2]
    x.uniq!
    assert_equal([1, 4, 2, 5], x)
  end

  def test_empty_0
    assert_equal true, [].empty?
    assert_equal false, [1].empty?
    assert_equal false, [1, 1, 4, 2, 5, 4, 5, 1, 2].empty?
  end

  def test_sort_0
    x = ["it", "came", "to", "pass", "that", "..."]
    x = x.sort.join(" ")
    assert_equal("... came it pass that to", x)
    x = [2,5,3,1,7]
    x.sort!{|a,b| a<=>b}		# sort with condition
    assert_equal([1,2,3,5,7], x)
    x.sort!{|a,b| b-a}		# reverse sort
    assert_equal([7,5,3,2,1], x)
  end

  def test_split_0
    x = "The Boassert of Mormon"
    assert_equal(x.reverse, x.split(//).reverse!.join)
    assert_equal(x.reverse, x.reverse!)
    assert_equal("g:n:i:r:t:s: :e:t:y:b: :1", "1 byte string".split(//).reverse.join(":"))
    x = "a b c  d"
    assert_equal(['a', 'b', 'c', 'd'], x.split)
    assert_equal(['a', 'b', 'c', 'd'], x.split(' '))
  end

  def test_misc_0
    assert(defined? "a".chomp)
    assert_equal(["a", "b", "c"], "abc".scan(/./))
    assert_equal([["1a"], ["2b"], ["3c"]], "1a2b3c".scan(/(\d.)/))
    # non-greedy match
    assert_equal([["a", "12"], ["b", "22"]], "a=12;b=22".scan(/(.*?)=(\d*);?/))

    x = [1]
    assert_equal('1:1:1:1:1', (x * 5).join(":"))
    assert_equal('1', (x * 1).join(":"))
    assert_equal('', (x * 0).join(":"))

    *x = *(1..7).to_a
    assert_equal(7, x.size)
    assert_equal([1, 2, 3, 4, 5, 6, 7], x)

    x = [1,2,3]
    x[1,0] = x
    assert_equal([1,1,2,3,2,3], x)

    x = [1,2,3]
    x[-1,0] = x
    assert_equal([1,2,1,2,3,3], x)

    x = [1,2,3]
    x.concat(x)
    assert_equal([1,2,3,1,2,3], x)

    x = [1,2,3]
    x.clear
    assert_equal([], x)

    x = [1,2,3]
    y = x.dup
    x << 4
    y << 5
    assert_equal([1,2,3,4], x)
    assert_equal([1,2,3,5], y)
  end

  def test_beg_end_0
    x = [1, 2, 3, 4, 5]
    
    assert_equal(1, x.first)
    assert_equal([1], x.first(1))
    assert_equal([1, 2, 3], x.first(3))
    
    assert_equal(5, x.last)
    assert_equal([5], x.last(1))
    assert_equal([3, 4, 5], x.last(3))
    
    assert_equal(1, x.shift)
    assert_equal([2, 3, 4], x.shift(3))
    assert_equal([5], x)
    
    assert_equal([2, 3, 4, 5], x.unshift(2, 3, 4))
    assert_equal([1, 2, 3, 4, 5], x.unshift(1))
    assert_equal([1, 2, 3, 4, 5], x)
    
    assert_equal(5, x.pop)
    assert_equal([3, 4], x.pop(2))
    assert_equal([1, 2], x)
    
    assert_equal([1, 2, 3, 4], x.push(3, 4))
    assert_equal([1, 2, 3, 4, 5], x.push(5))
    assert_equal([1, 2, 3, 4, 5], x)
  end

  def test_find_all_0
    assert_respond_to([], :find_all)
    assert_respond_to([], :select)       # Alias
    assert_equal([], [].find_all{ |obj| obj == "foo"})

    x = ["foo", "bar", "baz", "baz", 1, 2, 3, 3, 4]
    assert_equal(["baz","baz"], x.find_all{ |obj| obj == "baz" })
    assert_equal([3,3], x.find_all{ |obj| obj == 3 })
  end

  def test_fill_0
    assert_equal([-1, -1, -1, -1, -1, -1], [0, 1, 2, 3, 4, 5].fill(-1))
    assert_equal([0, 1, 2, -1, -1, -1], [0, 1, 2, 3, 4, 5].fill(-1, 3))
    assert_equal([0, 1, 2, -1, -1, 5], [0, 1, 2, 3, 4, 5].fill(-1, 3, 2))
    assert_equal([0, 1, 2, -1, -1, -1, -1, -1], [0, 1, 2, 3, 4, 5].fill(-1, 3, 5))
    assert_equal([0, 1, -1, -1, 4, 5], [0, 1, 2, 3, 4, 5].fill(-1, 2, 2))
    assert_equal([0, 1, -1, -1, -1, -1, -1], [0, 1, 2, 3, 4, 5].fill(-1, 2, 5))
    assert_equal([0, 1, 2, 3, -1, 5], [0, 1, 2, 3, 4, 5].fill(-1, -2, 1))
    assert_equal([0, 1, 2, 3, -1, -1, -1], [0, 1, 2, 3, 4, 5].fill(-1, -2, 3))
    assert_equal([0, 1, 2, -1, -1, 5], [0, 1, 2, 3, 4, 5].fill(-1, 3..4))
    assert_equal([0, 1, 2, -1, 4, 5], [0, 1, 2, 3, 4, 5].fill(-1, 3...4))
    assert_equal([0, 1, -1, -1, -1, 5], [0, 1, 2, 3, 4, 5].fill(-1, 2..-2))
    assert_equal([0, 1, -1, -1, 4, 5], [0, 1, 2, 3, 4, 5].fill(-1, 2...-2))
    assert_equal([10, 11, 12, 13, 14, 15], [0, 1, 2, 3, 4, 5].fill{|i| i+10})
    assert_equal([0, 1, 2, 13, 14, 15], [0, 1, 2, 3, 4, 5].fill(3){|i| i+10})
    assert_equal([0, 1, 2, 13, 14, 5], [0, 1, 2, 3, 4, 5].fill(3, 2){|i| i+10})
    assert_equal([0, 1, 2, 13, 14, 15, 16, 17], [0, 1, 2, 3, 4, 5].fill(3, 5){|i| i+10})
    assert_equal([0, 1, 2, 13, 14, 5], [0, 1, 2, 3, 4, 5].fill(3..4){|i| i+10})
    assert_equal([0, 1, 2, 13, 4, 5], [0, 1, 2, 3, 4, 5].fill(3...4){|i| i+10})
    assert_equal([0, 1, 12, 13, 14, 5], [0, 1, 2, 3, 4, 5].fill(2..-2){|i| i+10})
    assert_equal([0, 1, 12, 13, 4, 5], [0, 1, 2, 3, 4, 5].fill(2...-2){|i| i+10})
  end

  # From rubicon

  def setup
    @cls = Array
  end

  def test_00_new
    a = @cls.new()
    assert_instance_of(@cls, a)
    assert_equal(0, a.length)
    assert_nil(a[0])
  end

  def test_01_square_brackets
    a = @cls[ 5, 4, 3, 2, 1 ]
    assert_instance_of(@cls, a)
    assert_equal(5, a.length)
    5.times { |i| assert_equal(5-i, a[i]) }
    assert_nil(a[6])
  end

  def test_AND # '&'
    assert_equal(@cls[1, 3], @cls[ 1, 1, 3, 5 ] & @cls[ 1, 2, 3 ])
    assert_equal(@cls[],     @cls[ 1, 1, 3, 5 ] & @cls[ ])
    assert_equal(@cls[],     @cls[  ]           & @cls[ 1, 2, 3 ])
    assert_equal(@cls[],     @cls[ 1, 2, 3 ]    & @cls[ 4, 5, 6 ])
  end

  def test_MUL # '*'
    assert_equal(@cls[], @cls[]*3)
    assert_equal(@cls[1, 1, 1], @cls[1]*3)
    assert_equal(@cls[1, 2, 1, 2, 1, 2], @cls[1, 2]*3)
    assert_equal(@cls[], @cls[1, 2, 3] * 0)
    assert_raise(ArgumentError) { @cls[1, 2]*(-3) }

    assert_equal('1-2-3-4-5', @cls[1, 2, 3, 4, 5] * '-')
    assert_equal('12345',     @cls[1, 2, 3, 4, 5] * '')

  end

  def test_PLUS # '+'
    assert_equal(@cls[],     @cls[]  + @cls[])
    assert_equal(@cls[1],    @cls[1] + @cls[])
    assert_equal(@cls[1],    @cls[]  + @cls[1])
    assert_equal(@cls[1, 1], @cls[1] + @cls[1])
    assert_equal(@cls['cat', 'dog', 1, 2, 3], %w(cat dog) + (1..3).to_a)
  end

  def test_MINUS # '-'
    assert_equal(@cls[],  @cls[1] - @cls[1])
    assert_equal(@cls[1], @cls[1, 2, 3, 4, 5] - @cls[2, 3, 4, 5])
    # Ruby 1.8 feature change
    #assert_equal(@cls[1], @cls[1, 2, 1, 3, 1, 4, 1, 5] - @cls[2, 3, 4, 5])
    assert_equal(@cls[1, 1, 1, 1], @cls[1, 2, 1, 3, 1, 4, 1, 5] - @cls[2, 3, 4, 5])
    a = @cls[]
    1000.times { a << 1 }
    assert_equal(1000, a.length)
    #assert_equal(@cls[1], a - @cls[2])
    assert_equal(@cls[1] * 1000, a - @cls[2])
    #assert_equal(@cls[1],  @cls[1, 2, 1] - @cls[2])
    assert_equal(@cls[1, 1],  @cls[1, 2, 1] - @cls[2])
    assert_equal(@cls[1, 2, 3], @cls[1, 2, 3] - @cls[4, 5, 6])
  end

  def test_LSHIFT # '<<'
    a = @cls[]
    a << 1
    assert_equal(@cls[1], a)
    a << 2 << 3
    assert_equal(@cls[1, 2, 3], a)
    a << nil << 'cat'
    assert_equal(@cls[1, 2, 3, nil, 'cat'], a)
    a << a
    assert_equal(@cls[1, 2, 3, nil, 'cat', a], a)
  end

  def test_CMP # '<=>'
    assert_equal(0,  @cls[] <=> @cls[])
    assert_equal(0,  @cls[1] <=> @cls[1])
    assert_equal(0,  @cls[1, 2, 3, 'cat'] <=> @cls[1, 2, 3, 'cat'])
    assert_equal(-1, @cls[] <=> @cls[1])
    assert_equal(1,  @cls[1] <=> @cls[])
    assert_equal(-1, @cls[1, 2, 3] <=> @cls[1, 2, 3, 'cat'])
    assert_equal(1,  @cls[1, 2, 3, 'cat'] <=> @cls[1, 2, 3])
    assert_equal(-1, @cls[1, 2, 3, 'cat'] <=> @cls[1, 2, 3, 'dog'])
    assert_equal(1,  @cls[1, 2, 3, 'dog'] <=> @cls[1, 2, 3, 'cat'])
  end

  def test_EQUAL # '=='
    assert(@cls[] == @cls[])
    assert(@cls[1] == @cls[1])
    assert(@cls[1, 1, 2, 2] == @cls[1, 1, 2, 2])
    assert(@cls[1.0, 1.0, 2.0, 2.0] == @cls[1, 1, 2, 2])
  end

  def test_VERY_EQUAL # '==='
    assert(@cls[] === @cls[])
    assert(@cls[1] === @cls[1])
    assert(@cls[1, 1, 2, 2] === @cls[1, 1, 2, 2])
    assert(@cls[1.0, 1.0, 2.0, 2.0] === @cls[1, 1, 2, 2])
  end

  def test_AREF # '[]'
    a = @cls[*(1..100).to_a]

    assert_equal(1, a[0])
    assert_equal(100, a[99])
    assert_nil(a[100])
    assert_equal(100, a[-1])
    assert_equal(99,  a[-2])
    assert_equal(1,   a[-100])
    assert_nil(a[-101])
    assert_nil(a[-101,0])
    assert_nil(a[-101,1])
    assert_nil(a[-101,-1])
    assert_nil(a[10,-1])

    assert_equal(@cls[1],   a[0,1])
    assert_equal(@cls[100], a[99,1])
    assert_equal(@cls[],    a[100,1])
    assert_equal(@cls[100], a[99,100])
    assert_equal(@cls[100], a[-1,1])
    assert_equal(@cls[99],  a[-2,1])
    assert_equal(@cls[],    a[-100,0])
    assert_equal(@cls[1],   a[-100,1])

    assert_equal(@cls[10, 11, 12], a[9, 3])
    assert_equal(@cls[10, 11, 12], a[-91, 3])

    assert_equal(@cls[1],   a[0..0])
    assert_equal(@cls[100], a[99..99])
    assert_equal(@cls[],    a[100..100])
    assert_equal(@cls[100], a[99..200])
    assert_equal(@cls[100], a[-1..-1])
    assert_equal(@cls[99],  a[-2..-2])

    assert_equal(@cls[10, 11, 12], a[9..11])
    assert_equal(@cls[10, 11, 12], a[-91..-89])
    
    assert_nil(a[10, -3])
    # Ruby 1.8 feature change:
    # Array#[size..x] returns [] instead of nil.
    #assert_nil(a[10..7])
    assert_equal [], a[10..7]

    assert_raise(TypeError) {a['cat']}
  end

  def test_ASET # '[]='
    a = @cls[*(0..99).to_a]
    assert_equal(0, a[0] = 0)
    assert_equal(@cls[0] + @cls[*(1..99).to_a], a)

    a = @cls[*(0..99).to_a]
    assert_equal(0, a[10,10] = 0)
    assert_equal(@cls[*(0..9).to_a] + @cls[0] + @cls[*(20..99).to_a], a)

    a = @cls[*(0..99).to_a]
    assert_equal(0, a[-1] = 0)
    assert_equal(@cls[*(0..98).to_a] + @cls[0], a)

    a = @cls[*(0..99).to_a]
    assert_equal(0, a[-10, 10] = 0)
    assert_equal(@cls[*(0..89).to_a] + @cls[0], a)

    a = @cls[*(0..99).to_a]
    assert_equal(0, a[0,1000] = 0)
    assert_equal(@cls[0] , a)

    a = @cls[*(0..99).to_a]
    assert_equal(0, a[10..19] = 0)
    assert_equal(@cls[*(0..9).to_a] + @cls[0] + @cls[*(20..99).to_a], a)

    b = @cls[*%w( a b c )]
    a = @cls[*(0..99).to_a]
    assert_equal(b, a[0,1] = b)
    assert_equal(b + @cls[*(1..99).to_a], a)

    a = @cls[*(0..99).to_a]
    assert_equal(b, a[10,10] = b)
    assert_equal(@cls[*(0..9).to_a] + b + @cls[*(20..99).to_a], a)

    a = @cls[*(0..99).to_a]
    assert_equal(b, a[-1, 1] = b)
    assert_equal(@cls[*(0..98).to_a] + b, a)

    a = @cls[*(0..99).to_a]
    assert_equal(b, a[-10, 10] = b)
    assert_equal(@cls[*(0..89).to_a] + b, a)

    a = @cls[*(0..99).to_a]
    assert_equal(b, a[0,1000] = b)
    assert_equal(b , a)

    a = @cls[*(0..99).to_a]
    assert_equal(b, a[10..19] = b)
    assert_equal(@cls[*(0..9).to_a] + b + @cls[*(20..99).to_a], a)

    # Ruby 1.8 feature change:
    # assigning nil does not remove elements.
=begin
    a = @cls[*(0..99).to_a]
    assert_equal(nil, a[0,1] = nil)
    assert_equal(@cls[*(1..99).to_a], a)

    a = @cls[*(0..99).to_a]
    assert_equal(nil, a[10,10] = nil)
    assert_equal(@cls[*(0..9).to_a] + @cls[*(20..99).to_a], a)

    a = @cls[*(0..99).to_a]
    assert_equal(nil, a[-1, 1] = nil)
    assert_equal(@cls[*(0..98).to_a], a)

    a = @cls[*(0..99).to_a]
    assert_equal(nil, a[-10, 10] = nil)
    assert_equal(@cls[*(0..89).to_a], a)

    a = @cls[*(0..99).to_a]
    assert_equal(nil, a[0,1000] = nil)
    assert_equal(@cls[] , a)

    a = @cls[*(0..99).to_a]
    assert_equal(nil, a[10..19] = nil)
    assert_equal(@cls[*(0..9).to_a] + @cls[*(20..99).to_a], a)
=end

    a = @cls[1, 2, 3]
    a[1, 0] = a
    assert_equal([1, 1, 2, 3, 2, 3], a)

    a = @cls[1, 2, 3]
    a[-1, 0] = a
    assert_equal([1, 2, 1, 2, 3, 3], a)
  end

  def test_assoc
    a1 = @cls[*%w( cat feline )]
    a2 = @cls[*%w( dog canine )]
    a3 = @cls[*%w( mule asinine )]

    a = @cls[ a1, a2, a3 ]

    assert_equal(a1, a.assoc('cat'))
    assert_equal(a3, a.assoc('mule'))
    assert_equal(nil, a.assoc('asinine'))
    assert_equal(nil, a.assoc('wombat'))
    assert_equal(nil, a.assoc(1..2))
  end

  def test_at
    a = @cls[*(0..99).to_a]
    assert_equal(0,   a.at(0))
    assert_equal(10,  a.at(10))
    assert_equal(99,  a.at(99))
    assert_equal(nil, a.at(100))
    assert_equal(99,  a.at(-1))
    assert_equal(0,  a.at(-100))
    assert_equal(nil, a.at(-101))
    assert_raise(TypeError) { a.at('cat') }
  end

  def test_clear
    a = @cls[1, 2, 3]
    b = a.clear
    assert_equal(@cls[], a)
    assert_equal(@cls[], b)
    assert_equal(a.__id__, b.__id__)
  end

  def test_clone
    for taint in [ false, true ]
      for frozen in [ false, true ]
        a = @cls[*(0..99).to_a]
        a.taint  if taint
        a.freeze if frozen
        b = a.clone

        assert_equal(a, b)
        assert(a.__id__ != b.__id__)
        assert_equal(a.frozen?, b.frozen?)
        assert_equal(a.tainted?, b.tainted?)
      end
    end
  end

  def test_collect
    a = @cls[ 1, 'cat', 1..1 ]
    assert_equal([ Fixnum, String, Range], a.collect {|e| e.class} )
    assert_equal([ 99, 99, 99], a.collect { 99 } )

    assert_equal([], @cls[].collect { 99 })

    # Ruby 1.9 feature change:
    # Enumerable#collect without block returns an Enumerator.
    #assert_equal([1, 2, 3], @cls[1, 2, 3].collect)
    assert_kind_of Enumerable::Enumerator, @cls[1, 2, 3].collect
  end

  # also update map!
  def test_collect!
    a = @cls[ 1, 'cat', 1..1 ]
    assert_equal([ Fixnum, String, Range], a.collect! {|e| e.class} )
    assert_equal([ Fixnum, String, Range], a)
   
    a = @cls[ 1, 'cat', 1..1 ]
    assert_equal([ 99, 99, 99], a.collect! { 99 } )
    assert_equal([ 99, 99, 99], a)

    a = @cls[ ]
    assert_equal([], a.collect! { 99 })
    assert_equal([], a)
  end

  def test_compact
    a = @cls[ 1, nil, nil, 2, 3, nil, 4 ]
    assert_equal(@cls[1, 2, 3, 4], a.compact)

    a = @cls[ nil, 1, nil, 2, 3, nil, 4 ]
    assert_equal(@cls[1, 2, 3, 4], a.compact)

    a = @cls[ 1, nil, nil, 2, 3, nil, 4, nil ]
    assert_equal(@cls[1, 2, 3, 4], a.compact)

    a = @cls[ 1, 2, 3, 4 ]
    assert_equal(@cls[1, 2, 3, 4], a.compact)
  end

  def test_compact!
    a = @cls[ 1, nil, nil, 2, 3, nil, 4 ]
    assert_equal(@cls[1, 2, 3, 4], a.compact!)
    assert_equal(@cls[1, 2, 3, 4], a)

    a = @cls[ nil, 1, nil, 2, 3, nil, 4 ]
    assert_equal(@cls[1, 2, 3, 4], a.compact!)
    assert_equal(@cls[1, 2, 3, 4], a)

    a = @cls[ 1, nil, nil, 2, 3, nil, 4, nil ]
    assert_equal(@cls[1, 2, 3, 4], a.compact!)
    assert_equal(@cls[1, 2, 3, 4], a)

    a = @cls[ 1, 2, 3, 4 ]
    assert_equal(nil, a.compact!)
    assert_equal(@cls[1, 2, 3, 4], a)
  end

  def test_concat
    assert_equal(@cls[1, 2, 3, 4],     @cls[1, 2].concat(@cls[3, 4]))
    assert_equal(@cls[1, 2, 3, 4],     @cls[].concat(@cls[1, 2, 3, 4]))
    assert_equal(@cls[1, 2, 3, 4],     @cls[1, 2, 3, 4].concat(@cls[]))
    assert_equal(@cls[],               @cls[].concat(@cls[]))
    assert_equal(@cls[@cls[1, 2], @cls[3, 4]], @cls[@cls[1, 2]].concat(@cls[@cls[3, 4]]))
    
    a = @cls[1, 2, 3]
    a.concat(a)
    assert_equal([1, 2, 3, 1, 2, 3], a)
  end

  def test_delete
    a = @cls[*('cab'..'cat').to_a]
    assert_equal('cap', a.delete('cap'))
    assert_equal(@cls[*('cab'..'cao').to_a] + @cls[*('caq'..'cat').to_a], a)

    a = @cls[*('cab'..'cat').to_a]
    assert_equal('cab', a.delete('cab'))
    assert_equal(@cls[*('cac'..'cat').to_a], a)

    a = @cls[*('cab'..'cat').to_a]
    assert_equal('cat', a.delete('cat'))
    assert_equal(@cls[*('cab'..'cas').to_a], a)

    a = @cls[*('cab'..'cat').to_a]
    assert_equal(nil, a.delete('cup'))
    assert_equal(@cls[*('cab'..'cat').to_a], a)

    a = @cls[*('cab'..'cat').to_a]
    assert_equal(99, a.delete('cup') { 99 } )
    assert_equal(@cls[*('cab'..'cat').to_a], a)
  end

  def test_delete_at
    a = @cls[*(1..5).to_a]
    assert_equal(3, a.delete_at(2))
    assert_equal(@cls[1, 2, 4, 5], a)

    a = @cls[*(1..5).to_a]
    assert_equal(4, a.delete_at(-2))
    assert_equal(@cls[1, 2, 3, 5], a)

    a = @cls[*(1..5).to_a]
    assert_equal(nil, a.delete_at(5))
    assert_equal(@cls[1, 2, 3, 4, 5], a)

    a = @cls[*(1..5).to_a]
    assert_equal(nil, a.delete_at(-6))
    assert_equal(@cls[1, 2, 3, 4, 5], a)
  end

  # also reject!
  def test_delete_if
    a = @cls[ 1, 2, 3, 4, 5 ]
    assert_equal(a, a.delete_if { false })
    assert_equal(@cls[1, 2, 3, 4, 5], a)

    a = @cls[ 1, 2, 3, 4, 5 ]
    assert_equal(a, a.delete_if { true })
    assert_equal(@cls[], a)

    a = @cls[ 1, 2, 3, 4, 5 ]
    assert_equal(a, a.delete_if { |i| i > 3 })
    assert_equal(@cls[1, 2, 3], a)
  end

  def test_dup
    for taint in [ false, true ]
      for frozen in [ false, true ]
        a = @cls[*(0..99).to_a]
        a.taint  if taint
        a.freeze if frozen
        b = a.dup

        assert_equal(a, b)
        assert(a.__id__ != b.__id__)
        assert_equal(false, b.frozen?)
        assert_equal(a.tainted?, b.tainted?)
      end
    end
  end

  def test_each
    a = @cls[*%w( ant bat cat dog )]
    i = 0
    a.each { |e|
      assert_equal(a[i], e)
      i += 1
    }
    assert_equal(4, i)

    a = @cls[]
    i = 0
    a.each { |e|
      assert_equal(a[i], e)
      i += 1
    }
    assert_equal(0, i)

    assert_equal(a, a.each {})
  end

  def test_each_index
    a = @cls[*%w( ant bat cat dog )]
    i = 0
    a.each_index { |ind|
      assert_equal(i, ind)
      i += 1
    }
    assert_equal(4, i)

    a = @cls[]
    i = 0
    a.each_index { |ind|
      assert_equal(i, ind)
      i += 1
    }
    assert_equal(0, i)

    assert_equal(a, a.each_index {})
  end

  def test_empty?
    assert(@cls[].empty?)
    assert(!@cls[1].empty?)
  end

  def test_eql?
    assert(@cls[].eql?(@cls[]))
    assert(@cls[1].eql?(@cls[1]))
    assert(@cls[1, 1, 2, 2].eql?(@cls[1, 1, 2, 2]))
    assert(!@cls[1.0, 1.0, 2.0, 2.0].eql?(@cls[1, 1, 2, 2]))
  end

  def test_fill
    assert_equal(@cls[],   @cls[].fill(99))
    assert_equal(@cls[],   @cls[].fill(99, 0))
    assert_equal(@cls[99], @cls[].fill(99, 0, 1))
    assert_equal(@cls[99], @cls[].fill(99, 0..0))

    assert_equal(@cls[99],   @cls[1].fill(99))
    assert_equal(@cls[99],   @cls[1].fill(99, 0))
    assert_equal(@cls[99],   @cls[1].fill(99, 0, 1))
    assert_equal(@cls[99],   @cls[1].fill(99, 0..0))

    assert_equal(@cls[99, 99], @cls[1, 2].fill(99))
    assert_equal(@cls[99, 99], @cls[1, 2].fill(99, 0))
    assert_equal(@cls[99, 99], @cls[1, 2].fill(99, nil))
    assert_equal(@cls[1,  99], @cls[1, 2].fill(99, 1, nil))
    assert_equal(@cls[99,  2], @cls[1, 2].fill(99, 0, 1))
    assert_equal(@cls[99,  2], @cls[1, 2].fill(99, 0..0))
  end

  def test_first
    assert_equal(3,   @cls[3, 4, 5].first)
    assert_equal(nil, @cls[].first)
  end

  def test_flatten
    a1 = @cls[ 1, 2, 3]
    a2 = @cls[ 5, 6 ]
    a3 = @cls[ 4, a2 ]
    a4 = @cls[ a1, a3 ]
    assert_equal(@cls[1, 2, 3, 4, 5, 6], a4.flatten)
    assert_equal(@cls[ a1, a3], a4)

    a5 = @cls[ a1, @cls[], a3 ]
    assert_equal(@cls[1, 2, 3, 4, 5, 6], a5.flatten)
    assert_equal(@cls[], @cls[].flatten)
    assert_equal(@cls[], 
                 @cls[@cls[@cls[@cls[],@cls[]],@cls[@cls[]],@cls[]],@cls[@cls[@cls[]]]].flatten)

    assert_raise(TypeError, "[ruby-dev:31197]") { [[]].flatten("") }
  end

  def test_flatten!
    a1 = @cls[ 1, 2, 3]
    a2 = @cls[ 5, 6 ]
    a3 = @cls[ 4, a2 ]
    a4 = @cls[ a1, a3 ]
    assert_equal(@cls[1, 2, 3, 4, 5, 6], a4.flatten!)
    assert_equal(@cls[1, 2, 3, 4, 5, 6], a4)

    a5 = @cls[ a1, @cls[], a3 ]
    assert_equal(@cls[1, 2, 3, 4, 5, 6], a5.flatten!)
    assert_equal(@cls[1, 2, 3, 4, 5, 6], a5)

    assert_equal(@cls[], @cls[].flatten)
    assert_equal(@cls[], 
                 @cls[@cls[@cls[@cls[],@cls[]],@cls[@cls[]],@cls[]],@cls[@cls[@cls[]]]].flatten)
  end

  def test_hash
    a1 = @cls[ 'cat', 'dog' ]
    a2 = @cls[ 'cat', 'dog' ]
    a3 = @cls[ 'dog', 'cat' ]
    assert(a1.hash == a2.hash)
    assert(a1.hash != a3.hash)
  end

  def test_include?
    a = @cls[ 'cat', 99, /a/, @cls[ 1, 2, 3] ]
    assert(a.include?('cat'))
    assert(a.include?(99))
    assert(a.include?(/a/))
    assert(a.include?([1,2,3]))
    assert(!a.include?('ca'))
    assert(!a.include?([1,2]))
  end

  def test_index
    a = @cls[ 'cat', 99, /a/, 99, @cls[ 1, 2, 3] ]
    assert_equal(0, a.index('cat'))
    assert_equal(1, a.index(99))
    assert_equal(4, a.index([1,2,3]))
    assert_nil(a.index('ca'))
    assert_nil(a.index([1,2]))
  end

  def test_values_at
    a = @cls[*('a'..'j').to_a]
    assert_equal(@cls['a', 'c', 'e'], a.values_at(0, 2, 4))
    assert_equal(@cls['j', 'h', 'f'], a.values_at(-1, -3, -5))
    assert_equal(@cls['h', nil, 'a'], a.values_at(-3, 99, 0))
  end

  def test_join
    $, = ""
    a = @cls[]
    assert_equal("", a.join)
    assert_equal("", a.join(','))

    $, = ""
    a = @cls[1, 2]
    assert_equal("12", a.join)
    assert_equal("1,2", a.join(','))

    $, = ""
    a = @cls[1, 2, 3]
    assert_equal("123", a.join)
    assert_equal("1,2,3", a.join(','))

    $, = ":"
    a = @cls[1, 2, 3]
    assert_equal("1:2:3", a.join)
    assert_equal("1,2,3", a.join(','))

    $, = ""
  end

  def test_last
    assert_equal(nil, @cls[].last)
    assert_equal(1, @cls[1].last)
    assert_equal(99, @cls[*(3..99).to_a].last)
  end

  def test_length
    assert_equal(0, @cls[].length)
    assert_equal(1, @cls[1].length)
    assert_equal(2, @cls[1, nil].length)
    assert_equal(2, @cls[nil, 1].length)
    assert_equal(234, @cls[*(0..233).to_a].length)
  end

  # also update collect!
  def test_map!
    a = @cls[ 1, 'cat', 1..1 ]
    assert_equal(@cls[ Fixnum, String, Range], a.map! {|e| e.class} )
    assert_equal(@cls[ Fixnum, String, Range], a)
   
    a = @cls[ 1, 'cat', 1..1 ]
    assert_equal(@cls[ 99, 99, 99], a.map! { 99 } )
    assert_equal(@cls[ 99, 99, 99], a)

    a = @cls[ ]
    assert_equal(@cls[], a.map! { 99 })
    assert_equal(@cls[], a)
  end

  def test_nitems
    assert_equal(0, @cls[].nitems)
    assert_equal(1, @cls[1].nitems)
    assert_equal(1, @cls[1, nil].nitems)
    assert_equal(1, @cls[nil, 1].nitems)
    assert_equal(3, @cls[1, nil, nil, 2, nil, 3, nil].nitems)
  end

  def test_pack
    a = @cls[*%w( cat wombat x yy)]
    assert_equal("catwomx  yy ", a.pack("A3A3A3A3"))
    assert_equal("cat", a.pack("A*"))
    assert_equal("cwx  yy ", a.pack("A3@1A3@2A3A3"))
    assert_equal("catwomx\000\000yy\000", a.pack("a3a3a3a3"))
    assert_equal("cat", a.pack("a*"))
    assert_equal("ca", a.pack("a2"))
    assert_equal("cat\000\000", a.pack("a5"))

    assert_equal("\x61",     @cls["01100001"].pack("B8"))
    assert_equal("\x61",     @cls["01100001"].pack("B*"))
    assert_equal("\x61",     @cls["0110000100110111"].pack("B8"))
    assert_equal("\x61\x37", @cls["0110000100110111"].pack("B16"))
    assert_equal("\x61\x37", @cls["01100001", "00110111"].pack("B8B8"))
    assert_equal("\x60",     @cls["01100001"].pack("B4"))
    assert_equal("\x40",     @cls["01100001"].pack("B2"))

    assert_equal("\x86",     @cls["01100001"].pack("b8"))
    assert_equal("\x86",     @cls["01100001"].pack("b*"))
    assert_equal("\x86",     @cls["0110000100110111"].pack("b8"))
    assert_equal("\x86\xec", @cls["0110000100110111"].pack("b16"))
    assert_equal("\x86\xec", @cls["01100001", "00110111"].pack("b8b8"))
    assert_equal("\x06",     @cls["01100001"].pack("b4"))
    assert_equal("\x02",     @cls["01100001"].pack("b2"))

    assert_equal("ABC",      @cls[ 65, 66, 67 ].pack("C3"))
    assert_equal("\377BC",   @cls[ -1, 66, 67 ].pack("C*"))
    assert_equal("ABC",      @cls[ 65, 66, 67 ].pack("c3"))
    assert_equal("\377BC",   @cls[ -1, 66, 67 ].pack("c*"))

    
    assert_equal("AB\n\x10",  @cls["4142", "0a", "12"].pack("H4H2H1"))
    assert_equal("AB\n\x02",  @cls["1424", "a0", "21"].pack("h4h2h1"))

    assert_equal("abc=02def=\ncat=\n=01=\n", 
                 @cls["abc\002def", "cat", "\001"].pack("M9M3M4"))

    assert_equal("aGVsbG8K\n",  @cls["hello\n"].pack("m"))
    assert_equal(",:&5L;&\\*:&5L;&\\*\n",  @cls["hello\nhello\n"].pack("u"))

    assert_equal("\xc2\xa9B\xe2\x89\xa0", @cls[0xa9, 0x42, 0x2260].pack("U*"))


    format = "c2x5CCxsdils_l_a6";
    # Need the expression in here to force ary[5] to be numeric.  This avoids
    # test2 failing because ary2 goes str->numeric->str and ary does not.
    ary = [1, -100, 127, 128, 32767, 987.654321098/100.0,
      12345, 123456, -32767, -123456, "abcdef"]
    x    = ary.pack(format)
    ary2 = x.unpack(format)

    assert_equal(ary.length, ary2.length)
    assert_equal(ary.join(':'), ary2.join(':'))
    assert_not_nil(x =~ /def/)

=begin
    skipping "Not tested:
        D,d & double-precision float, native format\\
        E & double-precision float, little-endian byte order\\
        e & single-precision float, little-endian byte order\\
        F,f & single-precision float, native format\\
        G & double-precision float, network (big-endian) byte order\\
        g & single-precision float, network (big-endian) byte order\\
        I & unsigned integer\\
        i & integer\\
        L & unsigned long\\
        l & long\\

        N & long, network (big-endian) byte order\\
        n & short, network (big-endian) byte-order\\
        P & pointer to a structure (fixed-length string)\\
        p & pointer to a null-terminated string\\
        S & unsigned short\\
        s & short\\
        V & long, little-endian byte order\\
        v & short, little-endian byte order\\
        X & back up a byte\\
        x & null byte\\
        Z & ASCII string (null padded, count is width)\\
"
=end
  end

  def test_pop
    a = @cls[ 'cat', 'dog' ]
    assert_equal('dog', a.pop)
    assert_equal(@cls['cat'], a)
    assert_equal('cat', a.pop)
    assert_equal(@cls[], a)
    assert_nil(a.pop)
    assert_equal(@cls[], a)
  end

  def test_push
    a = @cls[1, 2, 3]
    assert_equal(@cls[1, 2, 3, 4, 5], a.push(4, 5))
    assert_equal(@cls[1, 2, 3, 4, 5, nil], a.push(nil))
    # Ruby 1.8 feature:
    # Array#push accepts any number of arguments.
    #assert_raise(ArgumentError, "a.push()") { a.push() }
    a.push
    assert_equal @cls[1, 2, 3, 4, 5, nil], a
    a.push 6, 7
    assert_equal @cls[1, 2, 3, 4, 5, nil, 6, 7], a
  end

  def test_rassoc
    a1 = @cls[*%w( cat  feline )]
    a2 = @cls[*%w( dog  canine )]
    a3 = @cls[*%w( mule asinine )]
    a  = @cls[ a1, a2, a3 ]

    assert_equal(a1,  a.rassoc('feline'))
    assert_equal(a3,  a.rassoc('asinine'))
    assert_equal(nil, a.rassoc('dog'))
    assert_equal(nil, a.rassoc('mule'))
    assert_equal(nil, a.rassoc(1..2))
  end

  # also delete_if
  def test_reject!
    a = @cls[ 1, 2, 3, 4, 5 ]
    assert_equal(nil, a.reject! { false })
    assert_equal(@cls[1, 2, 3, 4, 5], a)

    a = @cls[ 1, 2, 3, 4, 5 ]
    assert_equal(a, a.reject! { true })
    assert_equal(@cls[], a)

    a = @cls[ 1, 2, 3, 4, 5 ]
    assert_equal(a, a.reject! { |i| i > 3 })
    assert_equal(@cls[1, 2, 3], a)
  end

  def test_replace
    a = @cls[ 1, 2, 3]
    a_id = a.__id__
    assert_equal(@cls[4, 5, 6], a.replace(@cls[4, 5, 6]))
    assert_equal(@cls[4, 5, 6], a)
    assert_equal(a_id, a.__id__)
    assert_equal(@cls[], a.replace(@cls[]))
  end

  def test_reverse
    a = @cls[*%w( dog cat bee ant )]
    assert_equal(@cls[*%w(ant bee cat dog)], a.reverse)
    assert_equal(@cls[*%w(dog cat bee ant)], a)
    assert_equal(@cls[], @cls[].reverse)
  end

  def test_reverse!
    a = @cls[*%w( dog cat bee ant )]
    assert_equal(@cls[*%w(ant bee cat dog)], a.reverse!)
    assert_equal(@cls[*%w(ant bee cat dog)], a)
    # Ruby 1.8 feature change:
    # Array#reverse always returns self.
    #assert_nil(@cls[].reverse!)
    assert_equal @cls[], @cls[].reverse!
  end

  def test_reverse_each
    a = @cls[*%w( dog cat bee ant )]
    i = a.length
    a.reverse_each { |e|
      i -= 1
      assert_equal(a[i], e)
    }
    assert_equal(0, i)

    a = @cls[]
    i = 0
    a.reverse_each { |e|
      assert(false, "Never get here")
    }
    assert_equal(0, i)
  end

  def test_rindex
    a = @cls[ 'cat', 99, /a/, 99, [ 1, 2, 3] ]
    assert_equal(0, a.rindex('cat'))
    assert_equal(3, a.rindex(99))
    assert_equal(4, a.rindex([1,2,3]))
    assert_nil(a.rindex('ca'))
    assert_nil(a.rindex([1,2]))
  end

  def test_shift
    a = @cls[ 'cat', 'dog' ]
    assert_equal('cat', a.shift)
    assert_equal(@cls['dog'], a)
    assert_equal('dog', a.shift)
    assert_equal(@cls[], a)
    assert_nil(a.shift)
    assert_equal(@cls[], a)
  end

  def test_size
    assert_equal(0,   @cls[].size)
    assert_equal(1,   @cls[1].size)
    assert_equal(100, @cls[*(0..99).to_a].size)
  end

  def test_slice
    a = @cls[*(1..100).to_a]

    assert_equal(1, a.slice(0))
    assert_equal(100, a.slice(99))
    assert_nil(a.slice(100))
    assert_equal(100, a.slice(-1))
    assert_equal(99,  a.slice(-2))
    assert_equal(1,   a.slice(-100))
    assert_nil(a.slice(-101))

    assert_equal(@cls[1],   a.slice(0,1))
    assert_equal(@cls[100], a.slice(99,1))
    assert_equal(@cls[],    a.slice(100,1))
    assert_equal(@cls[100], a.slice(99,100))
    assert_equal(@cls[100], a.slice(-1,1))
    assert_equal(@cls[99],  a.slice(-2,1))

    assert_equal(@cls[10, 11, 12], a.slice(9, 3))
    assert_equal(@cls[10, 11, 12], a.slice(-91, 3))

    assert_nil(a.slice(-101, 2))

    assert_equal(@cls[1],   a.slice(0..0))
    assert_equal(@cls[100], a.slice(99..99))
    assert_equal(@cls[],    a.slice(100..100))
    assert_equal(@cls[100], a.slice(99..200))
    assert_equal(@cls[100], a.slice(-1..-1))
    assert_equal(@cls[99],  a.slice(-2..-2))

    assert_equal(@cls[10, 11, 12], a.slice(9..11))
    assert_equal(@cls[10, 11, 12], a.slice(-91..-89))
    
    assert_nil(a.slice(-101..-1))

    assert_nil(a.slice(10, -3))
    # Ruby 1.8 feature change:
    # Array#slice[size..x] always returns [].
    #assert_nil(a.slice(10..7))
    assert_equal @cls[], a.slice(10..7)
  end

  def test_slice!
    a = @cls[1, 2, 3, 4, 5]
    assert_equal(3, a.slice!(2))
    assert_equal(@cls[1, 2, 4, 5], a)

    a = @cls[1, 2, 3, 4, 5]
    assert_equal(4, a.slice!(-2))
    assert_equal(@cls[1, 2, 3, 5], a)

    a = @cls[1, 2, 3, 4, 5]
    assert_equal(@cls[3,4], a.slice!(2,2))
    assert_equal(@cls[1, 2, 5], a)

    a = @cls[1, 2, 3, 4, 5]
    assert_equal(@cls[4,5], a.slice!(-2,2))
    assert_equal(@cls[1, 2, 3], a)

    a = @cls[1, 2, 3, 4, 5]
    assert_equal(@cls[3,4], a.slice!(2..3))
    assert_equal(@cls[1, 2, 5], a)

    a = @cls[1, 2, 3, 4, 5]
    assert_equal(nil, a.slice!(20))
    assert_equal(@cls[1, 2, 3, 4, 5], a)

    a = @cls[1, 2, 3, 4, 5]
    assert_equal(nil, a.slice!(-6))
    assert_equal(@cls[1, 2, 3, 4, 5], a)

    a = @cls[1, 2, 3, 4, 5]
    assert_equal(nil, a.slice!(-6..4))
    assert_equal(@cls[1, 2, 3, 4, 5], a)

    a = @cls[1, 2, 3, 4, 5]
    assert_equal(nil, a.slice!(-6,2))
    assert_equal(@cls[1, 2, 3, 4, 5], a)
  end

  def test_sort
    a = @cls[ 4, 1, 2, 3 ]
    assert_equal(@cls[1, 2, 3, 4], a.sort)
    assert_equal(@cls[4, 1, 2, 3], a)

    assert_equal(@cls[4, 3, 2, 1], a.sort { |x, y| y <=> x} )
    assert_equal(@cls[4, 1, 2, 3], a)

    a.fill(1)
    assert_equal(@cls[1, 1, 1, 1], a.sort)
    
    assert_equal(@cls[], @cls[].sort)
  end

  def test_sort!
    a = @cls[ 4, 1, 2, 3 ]
    assert_equal(@cls[1, 2, 3, 4], a.sort!)
    assert_equal(@cls[1, 2, 3, 4], a)

    assert_equal(@cls[4, 3, 2, 1], a.sort! { |x, y| y <=> x} )
    assert_equal(@cls[4, 3, 2, 1], a)

    a.fill(1)
    assert_equal(@cls[1, 1, 1, 1], a.sort!)

    assert_equal(@cls[1], @cls[1].sort!)
    assert_equal(@cls[], @cls[].sort!)
  end

  def test_to_a
    a = @cls[ 1, 2, 3 ]
    a_id = a.__id__
    assert_equal(a, a.to_a)
    assert_equal(a_id, a.to_a.__id__)
  end

  def test_to_ary
    a = [ 1, 2, 3 ]
    b = @cls[*a]

    a_id = a.__id__
    assert_equal(a, b.to_ary)
    if (@cls == Array)
      assert_equal(a_id, a.to_ary.__id__)
    end
  end

  def test_to_s
    $, = ""
    a = @cls[]
    assert_equal("[]", a.to_s)

    $, = ""
    a = @cls[1, 2]
    assert_equal("[1, 2]", a.to_s)

    $, = ""
    a = @cls[1, 2, 3]
    assert_equal("[1, 2, 3]", a.to_s)

    $, = ":"
    a = @cls[1, 2, 3]
    assert_equal("[1, 2, 3]", a.to_s)

    $, = ""
  end

  def test_uniq
    a = @cls[ 1, 2, 3, 2, 1, 2, 3, 4, nil ]
    b = a.dup
    assert_equal(@cls[1, 2, 3, 4, nil], a.uniq)
    assert_equal(b, a)

    assert_equal(@cls[1, 2, 3], @cls[1, 2, 3].uniq)
  end

  def test_uniq!
    a = @cls[ 1, 2, 3, 2, 1, 2, 3, 4, nil ]
    assert_equal(@cls[1, 2, 3, 4, nil], a.uniq!)
    assert_equal(@cls[1, 2, 3, 4, nil], a)

    assert_nil(@cls[1, 2, 3].uniq!)
  end

  def test_unshift
    a = @cls[]
    assert_equal(@cls['cat'], a.unshift('cat'))
    assert_equal(@cls['dog', 'cat'], a.unshift('dog'))
    assert_equal(@cls[nil, 'dog', 'cat'], a.unshift(nil))
    assert_equal(@cls[@cls[1,2], nil, 'dog', 'cat'], a.unshift(@cls[1, 2]))
  end

  def test_OR # '|'
    assert_equal(@cls[],  @cls[]  | @cls[])
    assert_equal(@cls[1], @cls[1] | @cls[])
    assert_equal(@cls[1], @cls[]  | @cls[1])
    assert_equal(@cls[1], @cls[1] | @cls[1])

    assert_equal(@cls[1,2], @cls[1] | @cls[2])
    assert_equal(@cls[1,2], @cls[1, 1] | @cls[2, 2])
    assert_equal(@cls[1,2], @cls[1, 2] | @cls[1, 2])
  end

 def test_combination
    assert_equal(@cls[[]], @cls[1,2,3,4].combination(0).to_a)
    assert_equal(@cls[[1],[2],[3],[4]], @cls[1,2,3,4].combination(1).to_a)
    assert_equal(@cls[[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]], @cls[1,2,3,4].combination(2).to_a)
    assert_equal(@cls[[1,2,3],[1,2,4],[1,3,4],[2,3,4]], @cls[1,2,3,4].combination(3).to_a)
    assert_equal(@cls[[1,2,3,4]], @cls[1,2,3,4].combination(4).to_a)
    assert_equal(@cls[], @cls[1,2,3,4].combination(5).to_a)
  end

  def test_product
    assert_equal(@cls[[1,4],[1,5],[2,4],[2,5],[3,4],[3,5]],
                 @cls[1,2,3].product([4,5]))
    assert_equal(@cls[[1,1],[1,2],[2,1],[2,2]], @cls[1,2].product([1,2]))

    assert_equal(@cls[[1,3,5],[1,3,6],[1,4,5],[1,4,6],
                   [2,3,5],[2,3,6],[2,4,5],[2,4,6]], 
                 @cls[1,2].product([3,4],[5,6]))
    assert_equal(@cls[[1],[2]], @cls[1,2].product)
    assert_equal(@cls[], @cls[1,2].product([]))
  end

  def test_permutation
    a = @cls[1,2,3]
    assert_equal(@cls[[]], a.permutation(0).to_a)
    assert_equal(@cls[[1],[2],[3]], a.permutation(1).to_a.sort)
    assert_equal(@cls[[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]],
                 a.permutation(2).to_a.sort)
    assert_equal(@cls[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]],
                 a.permutation(3).sort.to_a)
    assert_equal(@cls[], a.permutation(4).to_a)
    assert_equal(@cls[], a.permutation(-1).to_a)
    assert_equal("abcde".each_char.to_a.permutation(5).sort,
                 "edcba".each_char.to_a.permutation(5).sort)
    assert_equal(@cls[].permutation(0).to_a, @cls[[]])

  end
end