##
# Array(Ext) Test

def assert_permutation_combination(exp, receiver, meth, *args)
  act = []
  ret = receiver.__send__(meth, *args) { |v| act << v }
  assert "assert_#{meth}" do
    assert_equal(exp, act.sort)
    assert_same(receiver, ret)
  end
end

def assert_permutation(exp, receiver, *args)
  assert_permutation_combination(exp, receiver, :permutation, *args)
end

def assert_combination(exp, receiver, *args)
  assert_permutation_combination(exp, receiver, :combination, *args)
end

def assert_repeated_permutation(exp, receiver, *args)
  assert_permutation_combination(exp, receiver, :repeated_permutation, *args)
end

def assert_repeated_combination(exp, receiver, *args)
  assert_permutation_combination(exp, receiver, :repeated_combination, *args)
end

assert("Array#assoc") do
  s1 = [ "colors", "red", "blue", "green" ]
  s2 = [ "letters", "a", "b", "c" ]
  s3 = "foo"
  a  = [ s1, s2, s3 ]

  assert_equal [ "letters", "a", "b", "c" ], a.assoc("letters")
  assert_nil a.assoc("foo")
end

assert("Array#at") do
  a = [ "a", "b", "c", "d", "e" ]
  assert_equal "a", a.at(0)
  assert_equal "e", a.at(-1)
end

assert("Array#rassoc") do
  a = [ [ 1, "one"], [2, "two"], [3, "three"], ["ii", "two"] ]

  assert_equal [2, "two"], a.rassoc("two")
  assert_nil a.rassoc("four")
end

assert("Array#uniq!") do
  a = [1, 2, 3, 1]
  a.uniq!
  assert_equal [1, 2, 3], a

  b = [ "a", "b", "c" ]
  assert_nil b.uniq!

  c = [["student","sam"], ["student","george"], ["teacher","matz"]]
  assert_equal [["student", "sam"], ["teacher", "matz"]], c.uniq! { |s| s.first }

  d = [["student","sam"], ["teacher","matz"]]
  assert_nil d.uniq! { |s| s.first }
end

assert("Array#uniq") do
  a = [1, 2, 3, 1]
  assert_equal [1, 2, 3], a.uniq
  assert_equal [1, 2, 3, 1], a

  b = [["student","sam"], ["student","george"], ["teacher","matz"]]
  assert_equal [["student", "sam"], ["teacher", "matz"]], b.uniq { |s| s.first }
end

assert("Array#-") do
  # Test basic functionality
  a = [1, 2, 3, 1]
  b = [1]
  c = 1

  assert_raise(TypeError) { a - c }
  assert_equal [2, 3], (a - b)
  assert_equal [1, 2, 3, 1], a

  # Test hash-based implementation (other_ary length > 32)
  a = (1..50).to_a
  b = (15..50).to_a  # 36 elements > 32, triggers hash approach
  result = a - b
  expected = (1..14).to_a

  assert_equal expected, result
  assert_equal 14, result.size

  # Test with larger removal set
  a = (1..60).to_a
  b = (20..55).to_a  # 36 elements > 32, triggers hash approach
  result = a - b
  expected = (1..19).to_a + (56..60).to_a

  assert_equal expected, result
  assert_equal 24, result.size

  # Test removing all elements
  a = (1..20).to_a
  b = (1..20).to_a
  result = a - b
  expected = []

  assert_equal expected, result
  assert_equal 0, result.size

  # Test removing no elements
  a = (1..20).to_a
  b = (30..50).to_a  # 21 elements > 16, triggers hash approach
  result = a - b
  expected = (1..20).to_a

  assert_equal expected, result
  assert_equal 20, result.size

  # Ensure original arrays are unchanged
  original_a = (1..30).to_a
  original_b = (10..25).to_a
  result = original_a - original_b
  assert_equal [1, 2, 3, 4, 5, 6, 7, 8, 9, 26, 27, 28, 29, 30], result
  assert_equal (1..30).to_a, original_a
  assert_equal (10..25).to_a, original_b
end

assert("Array#|") do
  a = [1, 2, 3, 1]
  b = [1, 4]
  c = 1

  assert_raise(TypeError) { a | c }
  assert_equal [1, 2, 3, 4], (a | b)
  assert_equal [1, 2, 3, 1], a
end

assert("Array#| with large arrays") do
  # Test hash-based implementation (total length > 32)
  a = (1..25).to_a
  b = (20..45).to_a  # total = 51 > 32, triggers hash approach
  result = a | b
  expected = (1..45).to_a

  assert_equal expected, result
  assert_equal 45, result.size

  # Test with overlapping ranges
  a = (1..20).to_a
  b = (15..35).to_a  # total = 41 > 32, triggers hash approach
  result = a | b
  expected = (1..35).to_a

  assert_equal expected, result
  assert_equal 35, result.size

  # Ensure original arrays are unchanged
  original_a = (1..20).to_a
  original_b = (18..50).to_a
  result = original_a | original_b
  assert_equal (1..50).to_a, result
  assert_equal (1..20).to_a, original_a
  assert_equal (18..50).to_a, original_b
end

assert("Array#union") do
  a = [1, 2, 3, 1]
  b = [1, 4]
  c = [1, 5]

  assert_equal [1, 2, 3, 4, 5], a.union(b,c)
end

assert("Array#difference") do
  a = [1, 2, 3, 1, 6, 7]
  b = [1, 4, 6]
  c = [1, 5, 7]

  assert_equal [2, 3], a.difference(b,c)
end

assert("Array#&") do
  a = [1, 2, 3, 1]
  b = [1, 4]
  c = 1

  assert_raise(TypeError) { a & c }
  assert_equal [1], (a & b)
  assert_equal [1, 2, 3, 1], a
end

assert("Array#& with large arrays") do
  # Test hash-based implementation (other_ary length > 32)
  a = (1..50).to_a
  b = (20..55).to_a  # 36 elements > 32, triggers hash approach
  result = a & b
  expected = (20..50).to_a

  assert_equal expected, result
  assert_equal 31, result.size

  # Test with larger intersection set
  a = (1..60).to_a
  b = (25..60).to_a  # 36 elements > 32, triggers hash approach
  result = a & b
  expected = (25..60).to_a

  assert_equal expected, result
  assert_equal 36, result.size

  # Test with duplicates in first array
  a = [1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10]
  b = (5..25).to_a  # 21 elements > 16, triggers hash approach
  result = a & b
  expected = [5, 6, 7, 8, 9, 10]  # no duplicates in result

  assert_equal expected, result
  assert_equal 6, result.size

  # Test no intersection
  a = (1..20).to_a
  b = (30..50).to_a  # 21 elements > 16, triggers hash approach
  result = a & b
  expected = []

  assert_equal expected, result
  assert_equal 0, result.size

  # Test complete intersection
  a = (1..20).to_a
  b = (1..20).to_a
  result = a & b
  expected = (1..20).to_a

  assert_equal expected, result
  assert_equal 20, result.size

  # Ensure original arrays are unchanged
  original_a = (1..30).to_a
  original_b = (10..25).to_a
  result = original_a & original_b
  assert_equal (10..25).to_a, result
  assert_equal (1..30).to_a, original_a
  assert_equal (10..25).to_a, original_b
end

assert("Array#intersection") do
  a = [1, 2, 3, 1, 8, 6, 7, 8]
  b = [1, 4, 6, 8]
  c = [1, 5, 7, 8]

  assert_equal [1, 8], a.intersection(b,c)
end

assert("Array#intersect?") do
  a = [ 1, 2, 3 ]
  b = [ 3, 4, 5 ]
  c = [ 5, 6, 7 ]
  assert_true(a.intersect?(b))
  assert_false(a.intersect?(c))
end

assert("Array#intersect? with large arrays") do
  # Test hash-based implementation (shorter array > 32)
  a = (1..50).to_a
  b = (40..75).to_a  # 36 elements > 32, but a is longer so b is shorter
  result = a.intersect?(b)
  assert_true(result)  # should find intersection at 40-50

  # Test with larger arrays, no intersection
  a = (1..30).to_a
  b = (50..85).to_a  # 36 elements > 32, triggers hash approach
  result = a.intersect?(b)
  assert_false(result)  # no intersection

  # Test with first element matching (early termination)
  a = (1..30).to_a
  b = [1] + (50..70).to_a  # 22 elements > 16, first element matches
  result = a.intersect?(b)
  assert_true(result)  # should terminate early on first element

  # Test with last element matching
  a = (1..30).to_a
  b = (50..70).to_a + [30]  # 22 elements > 16, last element matches
  result = a.intersect?(b)
  assert_true(result)  # should find match at the end

  # Test empty arrays
  a = []
  b = (1..20).to_a
  result = a.intersect?(b)
  assert_false(result)  # empty array intersects with nothing

  a = (1..20).to_a
  b = []
  result = a.intersect?(b)
  assert_false(result)  # intersecting with empty array

  # Test array size optimization (shorter array used for hash)
  a = (1..5).to_a  # shorter
  b = (3..30).to_a  # longer, 28 elements > 16
  result = a.intersect?(b)
  assert_true(result)  # should use a (shorter) for hash, find 3,4,5

  # Test with duplicates
  a = [1, 1, 2, 2, 3, 3] * 5  # 30 elements with duplicates
  b = (25..50).to_a  # 26 elements > 16, no intersection
  result = a.intersect?(b)
  assert_false(result)

  # Ensure original arrays are unchanged
  original_a = (1..30).to_a
  original_b = (25..50).to_a
  result = original_a.intersect?(original_b)
  assert_true(result)
  assert_equal (1..30).to_a, original_a
  assert_equal (25..50).to_a, original_b
end

assert("Array#flatten") do
  assert_equal [1, 2, "3", {4=>5}, :'6'],    [1, 2, "3", {4=>5}, :'6'].flatten
  assert_equal [1, 2, 3, 4, 5, 6], [1, 2,    [3, 4, 5], 6].flatten
  assert_equal [1, 2, 3, 4, 5, 6], [1, 2,    [3, [4, 5], 6]].flatten
  assert_equal [1, [2, [3, [4, [5, [6]]]]]], [1, [2, [3, [4, [5, [6]]]]]].flatten(0)
  assert_equal [1, 2, [3, [4, [5, [6]]]]],   [1, [2, [3, [4, [5, [6]]]]]].flatten(1)
  assert_equal [1, 2, 3, [4, [5, [6]]]],     [1, [2, [3, [4, [5, [6]]]]]].flatten(2)
  assert_equal [1, 2, 3, 4, [5, [6]]],       [1, [2, [3, [4, [5, [6]]]]]].flatten(3)
  assert_equal [1, 2, 3, 4, 5, [6]],         [1, [2, [3, [4, [5, [6]]]]]].flatten(4)
  assert_equal [1, 2, 3, 4, 5, 6],           [1, [2, [3, [4, [5, [6]]]]]].flatten(5)
end

assert("Array#flatten!") do
  assert_equal [1, 2, 3, 4, 5, 6], [1, 2, [3, [4, 5], 6]].flatten!
end

assert("Array#compact") do
  a = [1, nil, "2", nil, :t, false, nil]
  assert_equal [1, "2", :t, false], a.compact
  assert_equal [1, nil, "2", nil, :t, false, nil], a
end

assert("Array#compact!") do
  a = [1, nil, "2", nil, :t, false, nil]
  a.compact!
  assert_equal [1, "2", :t, false], a
end

assert("Array#fetch") do
  a = [ 11, 22, 33, 44 ]
  assert_equal 22, a.fetch(1)
  assert_equal 44, a.fetch(-1)
  assert_equal 'cat', a.fetch(4, 'cat')
  ret = 0
  a.fetch(100) { |i| ret = i }
  assert_equal 100, ret
  assert_raise(IndexError) { a.fetch(100) }

  # Additional edge cases
  assert_equal "default", [].fetch(0, "default")
  assert_equal "missing 5", ["a"].fetch(5) { |i| "missing #{i}" }
  assert_equal "from block", ["a"].fetch(5, "default") { "from block" }

  # Error message format
  begin
    ["a", "b"].fetch(5)
    assert_false true
  rescue IndexError => e
    assert_true e.message.include?("index 5 outside of array bounds: -2...2")
  end
end

assert("Array#fetch_values") do
  a = [ 11, 22, 33, 44 ]
  assert_equal([33, 11], a.fetch_values(2, 0))
  assert_raise(IndexError) { a.fetch_values(2, 5) }
  assert_equal([33, 55], a.fetch_values(2, 5) { |i| i*11 })
end

assert("Array#fill") do
  a = [ "a", "b", "c", "d" ]
  assert_equal ["x", "x", "x", "x"], a.fill("x")
  assert_equal ["x", "x", "x", "w"], a.fill("w", -1)
  assert_equal ["x", "x", "z", "z"], a.fill("z", 2, 2)
  assert_equal ["y", "y", "z", "z"], a.fill("y", 0..1)
  assert_equal [0, 1, 4, 9], a.fill { |i| i*i }
  assert_equal [0, 1, 8, 27], a.fill(-2) { |i| i*i*i }
  assert_equal [0, 2, 3, 27], a.fill(1, 2) { |i| i+1 }
  assert_equal [1, 2, 3, 27], a.fill(0..1) { |i| i+1 }
  assert_raise(ArgumentError) { a.fill }

  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([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})

  assert_equal [1, 2, 3, 4, 'x', 'x'], [1, 2, 3, 4, 5, 6].fill('x', -2..-1)
  assert_equal [1, 2, 3, 4, 'x', 6], [1, 2, 3, 4, 5, 6].fill('x', -2...-1)
  assert_equal [1, 2, 3, 4, 5, 6], [1, 2, 3, 4, 5, 6].fill('x', -2...-2)
  assert_equal [1, 2, 3, 4, 'x', 6], [1, 2, 3, 4, 5, 6].fill('x', -2..-2)
  assert_equal [1, 2, 3, 4, 5, 6], [1, 2, 3, 4, 5, 6].fill('x', -2..0)

  # Test extending array
  a = [1, 2]
  assert_equal [1, 2, nil, nil, "x"], a.fill("x", 4, 1)
end



assert("Array#reverse_each") do
  a = [ "a", "b", "c", "d" ]
  b = []
  a.reverse_each do |i|
    b << i
  end
  assert_equal [ "d", "c", "b", "a" ], b
end

assert("Array#rotate") do
  a = ["a", "b", "c", "d"]
  assert_equal ["b", "c", "d", "a"], a.rotate
  assert_equal ["a", "b", "c", "d"], a
  assert_equal ["c", "d", "a", "b"], a.rotate(2)
  assert_equal ["b", "c", "d", "a"], a.rotate(-3)
  assert_equal ["c", "d", "a", "b"], a.rotate(10)
  assert_equal [], [].rotate
end

assert("Array#rotate!") do
  a = ["a", "b", "c", "d"]
  assert_equal ["b", "c", "d", "a"], a.rotate!
  assert_equal ["b", "c", "d", "a"], a
  assert_equal ["d", "a", "b", "c"], a.rotate!(2)
  assert_equal ["a", "b", "c", "d"], a.rotate!(-3)
  assert_equal ["c", "d", "a", "b"], a.rotate(10)
  assert_equal [], [].rotate!
end

assert("Array#delete_if") do
  a = [1, 2, 3, 4, 5]
  assert_equal [1, 2, 3, 4, 5], a.delete_if { false }
  assert_equal [1, 2, 3, 4, 5], a

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

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

assert("Array#reject!") do
  a = [1, 2, 3, 4, 5]
  assert_nil a.reject! { false }
  assert_equal [1, 2, 3, 4, 5], a

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

  a = [1, 2, 3, 4, 5]
  assert_equal [1, 2, 3], a.reject! { |val| val > 3 }
  assert_equal [1, 2, 3], a
end

assert("Array#insert") do
  # Basic insertion
  a = [1, 2, 3]
  assert_same a, a.insert(1, 99)
  assert_equal [1, 99, 2, 3], a

  # Multiple elements
  a = [1, 2, 3]
  a.insert(2, 'a', 'b')
  assert_equal [1, 2, 'a', 'b', 3], a

  # Negative index
  a = [1, 2, 3, 4]
  a.insert(-2, 99)
  assert_equal [1, 2, 3, 99, 4], a

  # Negative index out of bounds
  a = [1, 2, 3]
  assert_raise(IndexError) { a.insert(-5, 99) }
  assert_equal [1, 2, 3], a

  # Insertion beyond bounds (creates nils)
  a = [1, 2]
  a.insert(5, 99)
  assert_equal [1, 2, nil, nil, nil, 99], a

  # Insertion at the end
  a = [1, 2, 3]
  a.insert(3, 99)
  assert_equal [1, 2, 3, 99], a

  # Insertion into an empty array
  a = []
  a.insert(0, 1, 2)
  assert_equal [1, 2], a

  # Insertion into an empty array at a non-zero index
  a = []
  a.insert(2, 99)
  assert_equal [nil, nil, 99], a

  # No-op (inserting zero elements)
  a = [1, 2, 3]
  a.insert(1)
  assert_equal [1, 2, 3], a

  # Return value is self
  a = [1, 2, 3]
  b = a.insert(1, 99)
  assert_same a, b

  # Large array insertion
  a = (0...1000).to_a
  a.insert(500, "x")
  assert_equal 1001, a.size
  assert_equal "x", a[500]
  assert_equal 499, a[499]
  assert_equal 500, a[501]
end

assert("Array#bsearch") do
  # Find minimum mode
  a = [0, 2, 4]
  assert_equal 0, a.bsearch{ |x| x >= -1 }
  assert_equal 0, a.bsearch{ |x| x >= 0 }
  assert_equal 2, a.bsearch{ |x| x >= 1 }
  assert_equal 2, a.bsearch{ |x| x >= 2 }
  assert_equal 4, a.bsearch{ |x| x >= 3 }
  assert_equal 4, a.bsearch{ |x| x >= 4 }
  assert_nil      a.bsearch{ |x| x >= 5 }

  # Find any mode
  a = [0, 4, 8]
  def between(lo, x, hi)
    if x < lo
      1
    elsif x > hi
      -1
    else
      0
    end
  end
  assert_nil      a.bsearch{ |x| between(-3, x, -1) }
  assert_equal 0, a.bsearch{ |x| between(-1, x,  1) }
  assert_nil      a.bsearch{ |x| between( 1, x,  3) }
  assert_equal 4, a.bsearch{ |x| between( 3, x,  5) }
  assert_nil      a.bsearch{ |x| between( 5, x,  7) }
  assert_equal 8, a.bsearch{ |x| between( 7, x,  9) }
  assert_nil      a.bsearch{ |x| between( 9, x, 11) }

  assert_equal 0, a.bsearch{ |x| between( 0, x,  3) }
  assert_equal 4, a.bsearch{ |x| between( 0, x,  4) }
  assert_equal 4, a.bsearch{ |x| between( 4, x,  8) }
  assert_equal 8, a.bsearch{ |x| between( 5, x,  8) }

  # Invalid block result
  assert_raise TypeError, 'invalid block result (must be numeric, true, false or nil)' do
    a.bsearch{ 'I like to watch the world burn' }
  end
end

# tested through Array#bsearch
#assert("Array#bsearch_index") do
#end

assert("Array#keep_if") do
  a = [1, 2, 3, 4, 5]
  assert_equal [1, 2, 3, 4, 5], a.keep_if { true }
  assert_equal [1, 2, 3, 4, 5], a

  a = [1, 2, 3, 4, 5]
  assert_equal [], a.keep_if { false }
  assert_equal [], a

  a = [1, 2, 3, 4, 5]
  assert_equal [4, 5], a.keep_if { |val| val > 3 }
  assert_equal [4, 5], a
end

assert("Array#select!") do
  a = [1, 2, 3, 4, 5]
  assert_nil a.select! { true }
  assert_equal [1, 2, 3, 4, 5], a

  a = [1, 2, 3, 4, 5]
  assert_equal [], a.select! { false }
  assert_equal [], a

  a = [1, 2, 3, 4, 5]
  assert_equal [4, 5], a.select! { |val| val > 3 }
  assert_equal [4, 5], a
end

assert('Array#values_at') do
  a = %w{red green purple white none}

  assert_equal %w{red purple none}, a.values_at(0, 2, 4)
  assert_equal ['green', 'white', nil, nil], a.values_at(1, 3, 5, 7)
  assert_equal ['none', 'white', 'white', nil], a.values_at(-1, -2, -2, -7)
  assert_equal ['none', nil, nil, 'red', 'green', 'purple'], a.values_at(4..6, 0...3)
  assert_raise(TypeError) { a.values_at 'tt' }
end

assert('Array#to_h') do
  assert_equal({}, [].to_h)
  assert_equal({a: 1, b:2}, [[:a, 1], [:b, 2]].to_h)

  assert_raise(TypeError)     { [1].to_h }
  assert_raise(ArgumentError) { [[1]].to_h }
end

assert("Array#dig") do
  h = [[[1]], 0]
  assert_equal(1, h.dig(0, 0, 0))
  assert_nil(h.dig(2, 0))
  assert_raise(TypeError) {h.dig(:a)}
end

assert("Array#slice!") do
  a = [1, 2, 3]
  b = a.slice!(0)
  c = [1, 2, 3, 4, 5]
  d = c.slice!(0, 2)
  e = [1, 2, 3, 4, 5]
  f = e.slice!(1..3)
  g = [1, 2, 3]
  h = g.slice!(-1)
  i = [1, 2, 3]
  j = i.slice!(0, -1)

  assert_equal(a, [2, 3])
  assert_equal(b, 1)
  assert_equal(c, [3, 4, 5])
  assert_equal(d, [1, 2])
  assert_equal(e, [1, 5])
  assert_equal(f, [2, 3, 4])
  assert_equal(g, [1, 2])
  assert_equal(h, 3)
  assert_equal(i, [1, 2, 3])
  assert_equal(j, nil)
end

assert("Array#permutation") do
  a = [1, 2, 3]
  assert_permutation([[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]], a)
  assert_permutation([[1],[2],[3]], a, 1)
  assert_permutation([[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]], a, 2)
  assert_permutation([[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]], a, 3)
  assert_permutation([[]], a, 0)
  assert_permutation([], a, 4)
  assert_permutation([], a, -1)
end

assert("Array#combination") do
  a = [1, 2, 3, 4]
  assert_combination([[1],[2],[3],[4]], a, 1)
  assert_combination([[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]], a, 2)
  assert_combination([[1,2,3],[1,2,4],[1,3,4],[2,3,4]], a, 3)
  assert_combination([[1,2,3,4]], a, 4)
  assert_combination([[]], a, 0)
  assert_combination([], a, 5)
  assert_combination([], a, -1)
end

assert('Array#transpose') do
  assert_equal([].transpose, [])
  assert_equal([[]].transpose, [])
  assert_equal([[1]].transpose, [[1]])
  assert_equal([[1,2,3]].transpose, [[1], [2], [3]])
  assert_equal([[1], [2], [3]].transpose, [[1,2,3]])
  assert_equal([[1,2], [3,4], [5,6]].transpose, [[1,3,5], [2,4,6]])
  assert_raise(TypeError) { [1].transpose }
  assert_raise(IndexError) { [[1], [2,3,4]].transpose }
end

assert "Array#product" do
  assert_equal [[1], [2], [3]], [1, 2, 3].product
  assert_equal [], [1, 2, 3].product([])
  assert_equal [], [1, 2, 3].product([4, 5, 6], [])

  expect = [[1, 5, 8], [1, 5, 9], [1, 6, 8], [1, 6, 9], [1, 7, 8], [1, 7, 9],
            [2, 5, 8], [2, 5, 9], [2, 6, 8], [2, 6, 9], [2, 7, 8], [2, 7, 9],
            [3, 5, 8], [3, 5, 9], [3, 6, 8], [3, 6, 9], [3, 7, 8], [3, 7, 9],
            [4, 5, 8], [4, 5, 9], [4, 6, 8], [4, 6, 9], [4, 7, 8], [4, 7, 9]]
  assert_equal expect, [1, 2, 3, 4].product([5, 6, 7], [8, 9])

  expect = [[1, 4, 7], [1, 4, 8], [1, 4, 9], [1, 5, 7], [1, 5, 8], [1, 5, 9], [1, 6, 7], [1, 6, 8], [1, 6, 9],
            [2, 4, 7], [2, 4, 8], [2, 4, 9], [2, 5, 7], [2, 5, 8], [2, 5, 9], [2, 6, 7], [2, 6, 8], [2, 6, 9],
            [3, 4, 7], [3, 4, 8], [3, 4, 9], [3, 5, 7], [3, 5, 8], [3, 5, 9], [3, 6, 7], [3, 6, 8], [3, 6, 9]]

  assert_equal expect, [1, 2, 3].product([4, 5, 6], [7, 8, 9])
  base = [1, 2, 3]
  x = []
  assert_equal base, base.product([4, 5, 6], [7, 8, 9]) { |e| x << e }
  assert_equal expect, x
end

assert("Array#repeated_combination") do
  a = [1, 2, 3]
  assert_raise(ArgumentError) { a.repeated_combination }
  #assert_kind_of(Enumerator, a.repeated_combination(1))
  assert_repeated_combination([[1],[2],[3]], a, 1)
  assert_repeated_combination([[1,1],[1,2],[1,3],[2,2],[2,3],[3,3]], a, 2)
  assert_repeated_combination([[1,1,1],[1,1,2],[1,1,3],[1,2,2],[1,2,3],[1,3,3],[2,2,2],
                               [2,2,3],[2,3,3],[3,3,3]], a, 3)
  assert_repeated_combination([[1,1,1,1],[1,1,1,2],[1,1,1,3],[1,1,2,2],[1,1,2,3],[1,1,3,3],
                               [1,2,2,2],[1,2,2,3],[1,2,3,3],[1,3,3,3],[2,2,2,2],[2,2,2,3],
                               [2,2,3,3],[2,3,3,3],[3,3,3,3]], a, 4)
  assert_repeated_combination([[1,1,1,1,1],[1,1,1,1,2],[1,1,1,1,3],[1,1,1,2,2],[1,1,1,2,3],
                               [1,1,1,3,3],[1,1,2,2,2],[1,1,2,2,3],[1,1,2,3,3],[1,1,3,3,3],
                               [1,2,2,2,2],[1,2,2,2,3],[1,2,2,3,3],[1,2,3,3,3],[1,3,3,3,3],
                               [2,2,2,2,2],[2,2,2,2,3],[2,2,2,3,3],[2,2,3,3,3],[2,3,3,3,3],
                               [3,3,3,3,3]], a, 5)
  assert_repeated_combination([[]], a, 0)
  assert_repeated_combination([], a, -1)
end

assert("Array#repeated_permutation") do
  a = [1, 2, 3]
  assert_raise(ArgumentError) { a.repeated_permutation }
  #assert_kind_of(Enumerator, a.repeated_permutation(1))
  assert_repeated_permutation([[1],[2],[3]], a, 1)
  assert_repeated_permutation([[1,1],[1,2],[1,3],[2,1],[2,2],[2,3],[3,1],[3,2],[3,3]], a, 2)
  assert_repeated_permutation([[1,1,1],[1,1,2],[1,1,3],[1,2,1],[1,2,2],[1,2,3],[1,3,1],[1,3,2],[1,3,3],
                               [2,1,1],[2,1,2],[2,1,3],[2,2,1],[2,2,2],[2,2,3],[2,3,1],[2,3,2],[2,3,3],
                               [3,1,1],[3,1,2],[3,1,3],[3,2,1],[3,2,2],[3,2,3],[3,3,1],[3,3,2],[3,3,3]],
                              a, 3)
  assert_repeated_permutation([[1,1,1,1],[1,1,1,2],[1,1,1,3],[1,1,2,1],[1,1,2,2],[1,1,2,3],
                               [1,1,3,1],[1,1,3,2],[1,1,3,3],[1,2,1,1],[1,2,1,2],[1,2,1,3],
                               [1,2,2,1],[1,2,2,2],[1,2,2,3],[1,2,3,1],[1,2,3,2],[1,2,3,3],
                               [1,3,1,1],[1,3,1,2],[1,3,1,3],[1,3,2,1],[1,3,2,2],[1,3,2,3],
                               [1,3,3,1],[1,3,3,2],[1,3,3,3],[2,1,1,1],[2,1,1,2],[2,1,1,3],
                               [2,1,2,1],[2,1,2,2],[2,1,2,3],[2,1,3,1],[2,1,3,2],[2,1,3,3],
                               [2,2,1,1],[2,2,1,2],[2,2,1,3],[2,2,2,1],[2,2,2,2],[2,2,2,3],
                               [2,2,3,1],[2,2,3,2],[2,2,3,3],[2,3,1,1],[2,3,1,2],[2,3,1,3],
                               [2,3,2,1],[2,3,2,2],[2,3,2,3],[2,3,3,1],[2,3,3,2],[2,3,3,3],
                               [3,1,1,1],[3,1,1,2],[3,1,1,3],[3,1,2,1],[3,1,2,2],[3,1,2,3],
                               [3,1,3,1],[3,1,3,2],[3,1,3,3],[3,2,1,1],[3,2,1,2],[3,2,1,3],
                               [3,2,2,1],[3,2,2,2],[3,2,2,3],[3,2,3,1],[3,2,3,2],[3,2,3,3],
                               [3,3,1,1],[3,3,1,2],[3,3,1,3],[3,3,2,1],[3,3,2,2],[3,3,2,3],
                               [3,3,3,1],[3,3,3,2],[3,3,3,3]], a, 4)
  assert_repeated_permutation([[]], a, 0)
  assert_repeated_permutation([], a, -1)
end

assert("Array#deconstruct") do
  # Basic functionality - returns self
  a = [1, 2, 3]
  result = a.deconstruct
  assert_equal([1, 2, 3], result)
  assert_true(result.equal?(a))

  # Empty array
  b = []
  result_empty = b.deconstruct
  assert_equal([], result_empty)
  assert_true(result_empty.equal?(b))

  # Mixed types
  c = [1, "hello", :symbol, nil, true]
  result_mixed = c.deconstruct
  assert_equal([1, "hello", :symbol, nil, true], result_mixed)
  assert_true(result_mixed.equal?(c))

  # Nested arrays
  d = [[1, 2], [3, 4], [5]]
  result_nested = d.deconstruct
  assert_equal([[1, 2], [3, 4], [5]], result_nested)
  assert_true(result_nested.equal?(d))
end

assert("Array#find") do
  # Basic find
  assert_equal 3, [1, 2, 3, 4, 5].find { |x| x > 2 }
  assert_equal 1, [1, 2, 3, 4, 5].find { |x| x < 2 }

  # No match returns nil
  assert_nil [1, 2, 3].find { |x| x > 10 }

  # Empty array
  assert_nil [].find { |x| x > 0 }

  # With ifnone callable
  assert_equal 0, [1, 2, 3].find(->{ 0 }) { |x| x > 10 }
  assert_equal "default", [1, 2, 3].find(->{ "default" }) { |x| x > 10 }

  # ifnone not called when match found
  called = false
  [1, 2, 3].find(->{ called = true; 0 }) { |x| x == 2 }
  assert_false called

  # Returns first match
  assert_equal 2, [1, 2, 2, 3].find { |x| x == 2 }

  # Works with different types
  assert_equal "b", ["a", "b", "c"].find { |x| x == "b" }
  assert_equal :bar, [:foo, :bar, :baz].find { |x| x == :bar }
end

assert("Array#rfind") do
  # Basic rfind - finds from end (first match scanning backwards)
  assert_equal 5, [1, 2, 3, 4, 5].rfind { |x| x > 2 }  # 5 is first match from end
  assert_equal 5, [1, 2, 3, 4, 5].rfind { |x| x > 0 }  # 5 is first match from end

  # Returns last occurrence when duplicates exist
  a = [1, 2, 3, 2, 1]
  assert_equal 2, a.rfind { |x| x == 2 }  # finds the 2 at index 3

  # No match returns nil
  assert_nil [1, 2, 3].rfind { |x| x > 10 }

  # Empty array
  assert_nil [].rfind { |x| x > 0 }

  # With ifnone callable
  assert_equal 0, [1, 2, 3].rfind(->{ 0 }) { |x| x > 10 }
  assert_equal "default", [1, 2, 3].rfind(->{ "default" }) { |x| x > 10 }

  # ifnone not called when match found
  called = false
  [1, 2, 3].rfind(->{ called = true; 0 }) { |x| x == 2 }
  assert_false called

  # Compare find vs rfind - same result for unique match
  arr = [1, 2, 3, 4, 3, 2, 1]
  assert_equal 3, arr.find { |x| x == 3 }   # first 3 (index 2)
  assert_equal 3, arr.rfind { |x| x == 3 }  # last 3 (index 4), same value

  # Different results with inequality - rfind scans from end
  assert_equal 3, arr.find { |x| x >= 3 }   # first >= 3 is 3 (at index 2)
  assert_equal 3, arr.rfind { |x| x >= 3 }  # scanning from end: 1,2,3 - 3 matches first

  # Works with different types
  assert_equal "b", ["a", "b", "c", "b", "a"].rfind { |x| x > "a" }  # scanning from end: a,b - b matches
end