Parentheses Checker

parentheses.rb

class ParenthesesChecker
  attr_reader :input

  def initialize(input)
    @input = input
  end

  def check_valid_parentheses
    if begins_incorrectly?  || ends_incorrectly? || unmatching_paren_count?
      false
    else
      true
    end
  end

  private

  def begins_incorrectly?
    input[0] == ")"
  end

  def ends_incorrectly?
    input[-1] == "("
  end

  def unmatching_paren_count?
    input.scan(")").count != input.scan("(").count
  end
end

parentheses_spec.rb

require_relative '../lib/parentheses'
describe ParenthesesChecker do
  describe "#check_valid_parentheses" do
    it "returns false if the passed in string begins with )" do
      parentheses_checker = ParenthesesChecker.new(")())")
      expect(parentheses_checker.check_valid_parentheses).to eq false
    end

    it "returns false if the passed in string ends with (" do
      parentheses_checker = ParenthesesChecker.new("((((")
      expect(parentheses_checker.check_valid_parentheses).to eq false
    end

    it "returns false if the number of ) is not equal to the number of (" do
      parentheses_checker = ParenthesesChecker.new("(()")
      expect(parentheses_checker.check_valid_parentheses).to eq false
    end

    it "returns true when valid" do
      parentheses_checker = ParenthesesChecker.new("(())")
      expect(parentheses_checker.check_valid_parentheses).to eq true
    end
  end
end