Parans Test

parans_test.rb

######
######   Write a function that accepts a string of parenthesis, return true if it is a valid string, false if not.  
######   Strings are valid if all parens close, ie: () or (()) or (()()()) are valid, ()), ((), )( etc. would be invalid.
######   An empty string is also valid.
######


require 'test/unit'

def valid_parans(string)
  return false if string[0] == ")"
  return true if string.strip == ""
  counter = 0
  
  string.each_char do |char|
    if char == "("
      counter += 1
    elsif char == ")"
      counter -= 1
    end
  end
  
  return true if counter == 0
  return false
end

class TestParansFunction < Test::Unit::TestCase
  
  def test_all
    assert valid_parans("()")
    assert valid_parans("(())")
    assert !valid_parans("()(")
    assert !valid_parans("()(()")
    assert !valid_parans("()((")
    assert !valid_parans("())")
    assert valid_parans("(()()())")
    assert !valid_parans(")(")
    assert valid_parans("")
    assert !valid_parans("((()")
    assert !valid_parans(")))(")
  end
  
end