robot-name_test.rb

require 'minitest/autorun'
require 'minitest/pride'
require_relative 'robot'

class RobotTest < MiniTest::Unit::TestCase
  def test_has_name
    assert_match /\w{2}\d{3}/, Robot.new.name
  end

  def test_name_sticks
    robot = Robot.new
    robot.name
    assert_equal robot.name, robot.name
  end

  def test_different_robots_have_different_names
    assert Robot.new.name != Robot.new.name
  end

  def test_reset_name
    robot = Robot.new
    name = robot.name
    robot.reset
    name2 = robot.name
    assert name != name2
    assert_match /\w{2}\d{3}/, name2
  end

  def test_instruction_count
    robot = Robot.new
    robot.name
    robot.reset
    robot.name
    assert_equal robot.instruction_count, 2
  end

  def test_timers
    t = Time.now
    reset_at = t + 3
    queried_at = t + 6
    robot = Robot.new(t)
    robot.reset(reset_at)
    assert_equal robot.timers(queried_at),
      "3 seconds since last boot, 6 seconds since creation"
  end
end

Considered using just Time.now since it wouldn't require injected times, but it slows down testing and is brittle. Not sure how better to do it.