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require 'minitest/reporters'
MiniTest::Unit.runner = MiniTest::SuiteRunner.new
MiniTest::Unit.runner.reporters << MiniTest::Reporters::SpecReporter.new
require 'minitest/autorun'
############## Page ??? ##############
# The Wheel class expected by the following test
class Wheel
attr_reader :rim, :tire
def initialize(rim, tire)
@rim = rim
@tire = tire
end
def diameter
rim + (tire * 2)
end
# ...
end
############## Page 205 ##############
class Gear
attr_reader :chainring, :cog, :wheel
def initialize(args)
@chainring = args[:chainring]
@cog = args[:cog]
@wheel = args[:wheel]
end
def gear_inches
# The object in the 'wheel' variable
# plays the 'Diameterizable' role.
ratio * wheel.diameter
end
def ratio
chainring / cog.to_f
end
# ...
end
############## Page 206 ##############
class GearTest < MiniTest::Unit::TestCase
def test_calculates_gear_inches
gear = Gear.new(
chainring: 52,
cog: 11,
wheel: Wheel.new(26, 1.5))
assert_in_delta(137.1,
gear.gear_inches,
0.01)
end
end
############## Page 207 ##############
class Wheel
attr_reader :rim, :tire
def initialize(rim, tire)
@rim = rim
@tire = tire
end
def width # <---- used to be 'diameter'
rim + (tire * 2)
end
# ...
end
############## Page 207 ##############
class Gear
# ...
def gear_inches
ratio * wheel.diameter # <--- obsolete
end
end
############## Page ?? ##############
# Full listing for above
class Gear
attr_reader :chainring, :cog, :wheel
def initialize(args)
@chainring = args[:chainring]
@cog = args[:cog]
@wheel = args[:wheel]
end
def gear_inches
ratio * wheel.diameter
end
def ratio
chainring / cog.to_f
end
# ...
end
############## Page 210 ##############
# Create a player of the 'Diameterizable' role
class DiameterDouble
def diameter
10
end
end
class GearTest < MiniTest::Unit::TestCase
def test_calculates_gear_inches
gear = Gear.new(
chainring: 52,
cog: 11,
wheel: DiameterDouble.new)
assert_in_delta(47.27,
gear.gear_inches,
0.01)
end
end
############## Page 212 ##############
class WheelTest < MiniTest::Unit::TestCase
def setup
@wheel = Wheel.new(26, 1.5)
end
def test_implements_the_diameterizable_interface
assert_respond_to(@wheel, :diameter)
end
def test_calculates_diameter
wheel = Wheel.new(26, 1.5)
assert_in_delta(29,
wheel.diameter,
0.01)
end
end
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