Test First Ruby - Timer : problems implementing Symbol#to_proc within the time_string method

Question

I know how to solve this by implementing a complex web of conditional statements inside the time_string method. However, I'm trying to put to use my newfound knowledge of the Symbol#to_proc method. As you can see, I built the 'padded' method and I'm trying to call it using the '&' syntax, but I keep getting this error message kicked back. I've tried a number of different formats but to no avail.

I keep getting this same error message:

"Undefined method 'seconds=' for nil:NilClass"

My Timer class definition from timer.rb:

class Timer
  attr_accessor :seconds

  def initialize
    @seconds = 0
  end

  def padded n
    "#{n}".rjust(2, '0')
  end

  def time_string
    t_hours = @seconds / 3600
    t_mins = (@seconds % 3600) / 60
    t_seconds = @seconds % 60
    @time_string = [t_hours, t_mins, t_seconds].map(&:padded).join(":")
  end
end

The Rspec code from timer_spec.rb:

# # Topics
#
# * classes
# * instance variables
# * string formats
# * modular arithmetic
#
# # Timer

require '09_timer'

describe "Timer" do
  before(:each) do
    @timer = Timer.new
  end

  it "should initialize to 0 seconds" do
      expect(@timer.seconds).to eq(0)
  end


  it "pads zero" do
    expect(@timer.padded(0)).to eq("00")
  end
  it "pads one" do
    expect(@timer.padded(1)).to eq("01")
  end
  it "doesn't pad a two-digit number" do
    expect(@timer.padded(12)).to eq("12")
  end

  describe "time_string" do

    before(:each) do
      @timer = Timer.new
    end

    it "should display 0 seconds as 00:00:00" do
      @timer.seconds = 0
      expect(@timer.time_string).to eq("00:00:00")
    end

    it "should display 12 seconds as 00:00:12" do
      @timer.seconds = 12
      expect(@timer.time_string).to eq("00:00:12")
    end

    it "should display 66 seconds as 00:01:06" do
      @timer.seconds = 66
      expect(@timer.time_string).to eq("00:01:06")
    end

    it "should display 4000 seconds as 01:06:40" do
      @timer.seconds = 4000
      expect(@timer.time_string).to eq("01:06:40")
    end
  end
end

The error message from my terminal:

MacBook-Air:test1 ***$ bundle exec rspec spec/09_timer_spec.rb

Timer
  should initialize to 0 seconds
  pads zero
  pads one
  doesn't pad a two-digit number
  time_string
    should display 0 seconds as 00:00:00 (FAILED - 1)

Failures:

  1) Timer time_string should display 0 seconds as 00:00:00
     Failure/Error: expect(@timer.time_string).to eq("00:00:00")
     NoMethodError:
       undefined method `padded' for 0:Fixnum

Answer 1

You have few "describe" blocks. You have defined "@timer" only in first. So you should copy

before(:each) do
  @timer = Timer.new
end

into each of "describe"s. Or move this block to higher scope.

Also good practise is to use rspec`s let and let!

Answer 2

Needed the following fix:

@time_string = [t_hours, t_mins, t_seconds].map(&method(:padded)).join(":")

As opposed to:

@time_string = [t_hours, t_mins, t_seconds].map(&:padded).join(":")