require 'test/unit'

class TestArity < Test::Unit::TestCase
  def err_mess(method_proc = nil, argc = 0)
    args = (1..argc).to_a
    err = assert_raise(ArgumentError) do
      case method_proc
      when nil
        yield
      when Symbol
        method(method_proc).call(*args)
      else
        method_proc.call(*args)
      end
    end
    s = err.to_s
    assert s =~ /wrong number of arguments \((.*)\)/, "Unexpected ArgumentError's message: #{s}"
    $1
  end

  def a
  end

  def b(a, b, c, d=1, e=2, f, g, h, i, &block)
  end

  def c(a, b, c, d=1, e=2, *rest)
  end

  def d(a, b: 42)
  end

  def e(a, b:42, **c)
  end

  def f(a, b, c=1, *rest, d: 3)
  end

  def test_method_err_mess
    assert_equal "1 for 0",     err_mess(:a, 1)
    assert_equal "10 for 7..9", err_mess(:b, 10)
    assert_equal "2 for 3+",    err_mess(:c, 2)
    assert_equal "2 for 1",     err_mess(:d, 2)
    assert_equal "0 for 1",     err_mess(:d, 0)
    assert_equal "2 for 1",     err_mess(:e, 2)
    assert_equal "0 for 1",     err_mess(:e, 0)
    assert_equal "1 for 2+",    err_mess(:f, 1)
  end

  def test_proc_err_mess
    assert_equal "0 for 1..2",  err_mess(->(b, c=42){}, 0)
    assert_equal "1 for 2+",    err_mess(->(a, b, c=42, *d){}, 1)
    assert_equal "3 for 4+",    err_mess(->(a, b, *c, d, e){}, 3)
    assert_equal "3 for 1..2",  err_mess(->(b, c=42){}, 3)
    assert_equal "1 for 0",     err_mess(->(&block){}, 1)
    # Double checking:
    p = Proc.new{|b, c=42| :ok}
    assert_equal :ok,  p.call(1, 2, 3)
    assert_equal :ok,  p.call
  end

  def test_message_change_issue_6085
    assert_equal "3 for 1..2",  err_mess{ SignalException.new(1, "", nil) }
    assert_equal "1 for 0",     err_mess{ Hash.new(1){} }
    assert_equal "3 for 1..2",  err_mess{ Module.send :define_method, 1, 2, 3 }
    assert_equal "1 for 2",     err_mess{ "".sub!(//) }
    assert_equal "0 for 1..2",  err_mess{ "".sub!{} }
    assert_equal "0 for 1+",    err_mess{ exec }
    assert_equal "0 for 1+",    err_mess{ Struct.new }
  end
end