require 'test/unit'
require 'ruby-units'
require 'uncertain'
require 'rubygems'
require 'yaml'
require 'chronic'

class Unit < Numeric
  @@USER_DEFINITIONS = {'<inchworm>' =>  [%w{inworm inchworm}, 0.0254, :length, %w{<meter>} ],
                        '<habenero>'   => [%{degH}, 100, :temperature, %w{<celcius>}]}
  Unit.setup
end

class Time
  @@forced_now = nil
  class << self
    alias :unforced_now :now
    def forced_now
      return @@forced_now ? @@forced_now : unforced_now
    end
    alias :now :forced_now
    
    def forced_now=(now)
      @@forced_now = now
    end
    
  end
end

class DateTime
  @@forced_now = nil
  class << self
    alias :unforced_now :now
    def forced_now
      return @@forced_now ? @@forced_now : unforced_now
    end
    alias :now :forced_now
    
    def forced_now=(now)
      @@forced_now = now
    end
    
  end
end

class TestRubyUnits < Test::Unit::TestCase
 
  def setup
    @april_fools = Time.at 1143910800
    @april_fools_datetime = DateTime.parse('2006-4-1 12:00')
    Time.forced_now = @april_fools
    DateTime.forced_now = @april_fools_datetime 
    #Unit.clear_cache
  end
  
  def teardown
    Time.forced_now = nil
    DateTime.forced_now = nil
  end
  
  def test_to_yaml
    unit = "1 mm".u
    assert_equal "--- !ruby/object:Unit \nscalar: 1.0\nnumerator: \n- <milli>\n- <meter>\ndenominator: \n- <1>\nsignature: 1\nbase_scalar: 0.001\n", unit.to_yaml    
  end

  def test_time
    a = Time.now
    assert_equal "s", a.to_unit.units
    assert_equal a + 3600, a + "1 h".unit
    assert_equal a - 3600, a - "1 h".unit
    b = Unit(a) + "1 h".unit
    assert_in_delta Time.now - "1 h".unit, "1 h".ago, 1
    assert_in_delta Time.now + 3600, "1 h".from_now, 1
    assert_in_delta "1 h".unit + Time.now, "1 h".from_now, 1
    assert_in_delta Time.now - 3600, "1 h".before_now, 1
    assert_in_delta (Time.now.unit - Time.now).unit.scalar, 0, 1
    assert_equal "60 min", "min".until(Time.now + 3600).to_s
    assert_equal "01:00", "min".since(Time.now - 3600).to_s("%H:%M")
    assert_in_delta Time.now, "now".time, 1
  end
  
  def test_time_helpers
    assert_equal @april_fools, Time.now
    assert_equal "1 day".from_now, @april_fools + 86400
    assert_equal "1 day".from("now"), @april_fools + 86400
    assert_equal "1 day".ago, @april_fools - 86400
    assert_equal "1 day".before_now, @april_fools - 86400
    assert_equal '1 days'.before('now'), @april_fools - 86400
    assert_equal 'days'.since(@april_fools - 86400), "1 day".unit
    assert_equal 'days'.since('3/31/06 12:00'), "1 day".unit
    assert_equal 'days'.since(DateTime.parse('2006-3-31 12:00')), "1 day".unit
    assert_equal 'days'.until('4/2/2006'), '1 day'.unit
    assert_equal 'now'.time, Time.now
    assert_equal 'now'.datetime, DateTime.now
    assert_raises(ArgumentError) { 'days'.until(1) }
    assert_raises(ArgumentError) { 'days'.since(1) }
    assert_equal Unit.new(Time.now).scalar,  1143910800
    assert_equal @april_fools.unit.to_time, @april_fools
    assert_equal Time.in('1 day'), @april_fools + 86400
    assert_equal @april_fools_datetime.inspect, "2006-04-01T12:00:00Z"
  end
  
  def test_string_helpers
    assert_equal '1 mm'.to('in'), Unit('1 mm').to('in')
  end
  
  def test_math
    pi = Math::PI
    assert_equal Math.sin(pi), Math.sin("180 deg".unit)
    assert_equal Math.cos(pi), Math.cos("180 deg".unit)
    assert_equal Math.tan(pi), Math.tan("180 deg".unit)
    assert_equal Math.sinh(pi), Math.sinh("180 deg".unit)
    assert_equal Math.cosh(pi), Math.cosh("180 deg".unit)
    assert_equal Math.tanh(pi), Math.tanh("180 deg".unit)
  end

  def test_clone
    unit1= "1 mm".unit
    unit2 = unit1.clone
    assert_not_equal unit1.numerator.object_id, unit2.numerator.object_id
    assert_not_equal unit1.denominator.object_id, unit2.denominator.object_id
    assert unit1 === unit2
  end 
  
  def test_unary_minus
    unit1 = Unit.new("1 mm")
    unit2 = Unit.new("-1 mm")
    assert_equal unit1, -unit2
  end
  
  def test_unary_plus
    unit1 = Unit.new("1 mm")
    assert_equal unit1, +unit1
  end

  def test_create_unit_only
    unit1 = Unit.new("m")
    assert_equal ['<meter>'], unit1.numerator
    assert_equal 1.0, unit1.scalar
  end
  
  def test_to_base
    unit1 = Unit.new("100 cm")
    assert_in_delta 1, 0.001, unit1.to_base.scalar
    unit2 = Unit("1 mm^2 ms^-2")
    assert_in_delta 1, 0.001, unit2.to_base.scalar
  end
  
  def test_to_unit
    unit1 = "1 mm".to_unit
    assert_equal unit1, unit1.to_unit
    assert Unit === unit1
    unit2 = Unit("1 mm")
    assert Unit === unit1
    assert unit1 == unit2
    unit1 = "2.54 cm".to_unit("in")
    assert_in_delta 1, 0.001, unit1.scalar
    assert_equal ['<inch>'], unit1.numerator
    unit1 = "2.54 cm".unit("in")
    assert_in_delta 1, 0.001, unit1.scalar
    assert_equal ['<inch>'], unit1.numerator
    unit1 = 1.unit
    assert_in_delta 1, 0.001, unit1.scalar
    assert_equal ['<1>'], unit1.numerator
    unit1 = [1,'mm'].unit
    assert_in_delta 1, 0.001, unit1.scalar
    assert_equal ['<milli>','<meter>'], unit1.numerator
  end
  
  def test_create_unitless
    unit1 = Unit("1")
    assert_equal 1, unit1.to_f
    assert_equal ['<1>'],unit1.numerator
    assert_equal ['<1>'],unit1.denominator
    unit1 = Unit.new("1.5")
    assert_equal 1.5,unit1.to_f
    assert_equal ['<1>'],unit1.numerator
    assert_equal ['<1>'],unit1.denominator
  end
  
  def test_create_simple
    unit1 = Unit.new("1 m")
    assert_equal 1,unit1.scalar
    assert_equal ['<meter>'], unit1.numerator
    assert_equal ['<1>'],unit1.denominator
  end
  
  def test_create_compound
    unit1 = Unit.new("1 N*m")
    assert_equal 1,unit1.scalar 
    assert_equal ['<newton>','<meter>'],unit1.numerator
    assert_equal ['<1>'],unit1.denominator
  end
  
  def test_create_with_denominator
    unit1 = Unit.new("1 m/s")
    assert_equal 1, unit1.scalar
    assert_equal ['<meter>'],unit1.numerator
    assert_equal ['<second>'],unit1.denominator
  end
  
  def test_create_with_powers
    unit1 = Unit.new("1 m^2/s^2")
    assert_equal 1, unit1.scalar
    assert_equal ['<meter>','<meter>'],unit1.numerator
    assert_equal ['<second>','<second>'],unit1.denominator
    unit1 = Unit.new("1 m^2 kg^2 J^2/s^2")
    assert_equal 1, unit1.scalar
    assert_equal ['<meter>','<meter>','<kilogram>','<kilogram>','<joule>','<joule>'],unit1.numerator
    assert_equal ['<second>','<second>'],unit1.denominator
    
  end

  def test_create_with_zero_power
    unit1 = Unit.new("1 m^0")
    assert_equal 1,unit1.scalar
    assert_equal ['<1>'],unit1.numerator
    assert_equal ['<1>'],unit1.denominator
  end

  def test_create_with_negative_powers
    unit1 = Unit.new("1 m^2 s^-2")
    assert_equal 1, unit1.scalar
    assert_equal ['<meter>','<meter>'],unit1.numerator
    assert_equal ['<second>','<second>'],unit1.denominator
  end
  
  def test_create_from_array
    unit1 = Unit.new(1, "mm^2", "ul^2")
    assert_equal 1, unit1.scalar
    assert_equal ['<milli>','<meter>','<milli>','<meter>'], unit1.numerator
    assert_equal ['<micro>','<liter>','<micro>','<liter>'], unit1.denominator
  end
  
  def test_bad_create
    assert_raises(ArgumentError) { Unit.new(nil)}
    assert_raises(ArgumentError) { Unit.new(true)}
    assert_raises(ArgumentError) { Unit.new(false)}
    assert_raises(ArgumentError) { Unit.new(/(.+)/)}
  end
  
  def test_convert
    unit1 = Unit.new("1 attoparsec/microfortnight")
    assert_nothing_raised {
      unit2 = unit1 >> "in/s"
      assert_equal ['<inch>'],unit2.numerator
      assert_equal ['<second>'],unit2.denominator
      assert_in_delta 1.0043269330917,unit2.scalar,0.00001 
    }
  end
  
  def test_add_operator
    a = '0 mm'.unit
    b = '10 cm'.unit
    c = '1 in'.unit
    d = '1 ml'.unit
    
    assert_equal (a+b).scalar, 100
    assert_equal (a+b).units, 'mm'
    assert_equal (b+a).scalar, 10
    assert_equal (b+a).units, 'cm'
    assert_in_delta 0.01, (b+c).scalar, 12.54
    assert_equal (b+c).units, 'cm'
    assert_raises(ArgumentError) {
      a + d
    }
  end
  
  def test_subtract_operator
    a = '0 mm'.unit
    b = '10 cm'.unit
    c = '1 in'.unit
    d = '1 ml'.unit
    
    assert_equal (a-b).scalar, -100
    assert_equal (a-b).units, 'mm'
    assert_equal (b-a).scalar, 10
    assert_equal (b-a).units, 'cm'
    assert_in_delta 0.01, (b-c).scalar, 7.46
    assert_equal (b-c).units, 'cm'
    assert_raises(ArgumentError) {
      a - d
    }
  end
  
  def test_convert_to
    unit1 = Unit.new("1 mm")
    unit2 = Unit.new("1 ft")
    assert_nothing_raised {
      unit3 = unit1 >> unit2
      assert_equal ['<foot>'], unit3.numerator
      assert_equal ['<1>'],unit3.denominator
      unit3 = unit1 >> "ft"
      assert_equal ['<foot>'], unit3.numerator
      assert_equal ['<1>'],unit3.denominator
    }
    assert_raises(ArgumentError) { unit3= unit1 >> 5.0}
    assert_equal unit1, unit1.to(true)
    assert_equal unit1, unit1.to(false)
    assert_equal unit1, unit1.to(nil)
  end
  
  def test_compare 
    unit1 = "1 mm".unit
    unit2 = "1 mm".unit
    unit3 = unit2 >> "in"
    assert unit1 === unit2
    assert !(unit1 === unit3)
    assert unit1 === "1 mm"
  end
  
  def test_matched_units
    unit1 = Unit.new("1 m*kg/s")
    unit2 = Unit.new("1 in*pound/min")
    assert unit1 =~ unit2
  end
  
  def test_matched_units_using_string
    unit1 = Unit.new("1 m*kg/s")
    assert unit1 =~ "in*pound/min"
  end
  
  def test_unmatched_units
    unit1 = Unit.new("1 m*kg/s")
    unit2 = Unit.new("1 mm")
    assert unit1 !~ unit2
  end
  
  def test_comparison_like_units
    unit1 = Unit.new("1 in")
    unit2 = Unit.new("1 mm")
    assert_nothing_raised {
      assert unit1 > unit2
    }
  end
  
  def test_comparison_unlike_units
    unit1 = Unit.new("1 kg")
    unit2 = Unit.new("1 mm")
    assert_raise(ArgumentError) { unit1 > unit2 }
  end
  
  def test_add_like_units
    unit1 = Unit.new("1 mm")
    unit2 = Unit.new("2 mm")
    assert_nothing_raised {  
      assert_equal 3.0, (unit1+unit2).scalar
      }
  end
  
  def test_add_similar_units
    unit1 = Unit.new("1 cm")
    unit2 = Unit.new("1 in")
    assert_nothing_raised {
      unit3 = unit1 + unit2
      assert_in_delta 3.54, unit3.scalar, 0.01
      }
  end

  def test_subtract_similar_units
    unit1 = Unit.new("1 cm")
    unit2 = Unit.new("1 in")
    assert_nothing_raised {
      unit3 = unit1 - unit2
      assert_in_delta(-1.54, unit3.scalar, 0.01)
      }
  end
  
  def test_add_unlike_units
    unit1 = Unit.new("1 mm")
    unit2 = Unit.new("2 ml")
    assert_raise(ArgumentError) {(unit1+unit2).scalar}
  end
  
  def test_add_coerce
    unit1 = "1 mm".unit
    assert_nothing_raised {
      unit2 = unit1 + "1 mm"
      assert_equal "2 mm".unit, unit2
    }
    assert_nothing_raised {
      unit2 = unit1 + [1,"mm"]
      assert_equal "2 mm".unit, unit2
    }
    assert_nothing_raised {
      unit2 = "1".unit + 1
      assert_equal "2".unit, unit2
    }
    assert_raises(ArgumentError) {
      unit2 = "1".unit + nil
    }
  end

  def test_subtract_coerce
    unit1 = "1 mm".unit
    assert_nothing_raised {
      unit2 = unit1 - "1 mm"
      assert_equal "0 mm".unit, unit2
    }
  end
  def test_multiply_coerce
    unit1 = "1 mm".unit
    assert_nothing_raised {
      unit2 = unit1 * "1 mm"
      assert_equal "1 mm^2".unit, unit2
    }
  end
  def test_divide_coerce
    unit1 = "1 mm".unit
    assert_nothing_raised {
      unit2 = unit1 / "1 mm"
      assert_equal "1".unit, unit2
    }
  end
  
  def test_signature #"1 m s deg K kg A mol cd byte rad
    unit1 = Unit.new("1 m*s*degK*kg*A*mol*cd*byte*rad*dollar")
    assert_equal unit1.signature, (0..9).inject(0) {|product, n| product + 20**n}
  end
  
  def test_subtract_like_units
    unit1 = Unit.new("1 mm")
    unit2 = Unit.new("2 mm")
    assert_nothing_raised {
      assert_equal(-1, (unit1-unit2).scalar)
      }
  end
  
  def test_subtract_unlike_units
    unit1 = Unit.new("1 mm")
    unit2 = Unit.new("2 ml")
    assert_raise(ArgumentError) {(unit1-unit2).scalar}
  end
  
  def test_multiply
    unit1 = Unit.new("1 m/ms")
    unit2 = Unit.new("1 m/ms")
    assert_nothing_raised {
      unit3 = unit1 * unit2
      assert_equal Unit.new("1 m^2/ms^2"), unit3    
    }
    assert_equal unit1 * 0, '0 m/ms'.unit
  end
  
  def test_divide
    unit1 = Unit.new("200 M*g/mol")
    unit2 = Unit.new("200 g/mole")
    assert_nothing_raised {
      unit3 = unit1 / unit2
      assert_equal Unit.new("1 M"), unit3
      }
    assert_equal unit2 / 1, unit2
    unit3 = '0 s'.unit
    assert_raises(ZeroDivisionError) {
      unit1 / unit3
    }
    
    assert_raises(ZeroDivisionError) {
      unit1 / 0
    }
  end
  
  def test_inverse
    unit1 = Unit.new("1 m")
    unit2 = Unit.new("1 1/m")
    assert_equal unit2, unit1.inverse
    assert_raises (ZeroDivisionError) { 0.unit.inverse }
  end
  
  def test_exponentiate_positive
    unit1 = Unit.new("1 mm")
    unit2 = Unit.new("1 mm^2")
    assert_nothing_raised {
      assert_equal unit2, unit1**2
      }
  end
  
  def test_exponentiate_float
    unit1 = Unit.new("1 mm")
    assert_raise(ArgumentError) {unit1**2.5}
  end
   
  def test_exponentiate_negative
    unit1 = Unit.new("1 m")
    unit2 = Unit.new("1 m^-2")
    assert_nothing_raised {
      assert_equal unit2, unit1**-2
      }
    assert_raises(ZeroDivisionError) {
      unit="0 mm".unit**-1
    }
  end

  def test_exponentiate_zero
    unit1 = Unit.new("10 mm")
    unit2 = Unit.new("1")
    assert_nothing_raised {
      assert_equal unit2, unit1**0
    }
    assert_equal 1, "0 mm".unit**0
  end
  
  def test_abs
    unit1 = Unit.new("-1 mm")
    assert_equal 1, unit1.abs
  end
  
  def test_ceil
    unit1 = Unit.new("1.1 mm")
    unit2 = Unit.new("2 mm")
    assert_equal unit2, unit1.ceil
  end
  
  def test_floor
    unit1 = Unit.new("1.1 mm")
    unit2 = Unit.new("1 mm")
    assert_equal unit2, unit1.floor
  end
  
  def test_to_int
    assert_raises(RuntimeError)  {Unit.new("1.1 mm").to_i}
    assert_nothing_raised {Unit.new(10.5).to_i}
  end
  
  def test_truncate
    unit1 = Unit.new("1.1 mm")
    unit2 = Unit.new("1 mm")
    assert_equal unit2, unit1.truncate
  end
  
  def test_round
    unit1 = Unit.new("1.1 mm")
    unit2 = Unit.new("1 mm")
    assert_equal unit2, unit1.round
  end
  
  def test_zero?
    unit1 = Unit.new("0")
    assert unit1.zero?
  end
  
  def test_nonzero?
    unit1 = Unit.new("0")
    unit2 = Unit.new("1 mm")
    assert_nil unit1.nonzero?
    assert_equal unit2, unit2.nonzero?
  end
  
  def test_equality
    unit1 = Unit.new("1 cm")
    unit2 = Unit.new("10 mm")
    assert unit1 == unit2
  end
  
  def test_temperature_conversions
    assert_in_delta '0 tempC'.unit.scalar, '273.15 degK'.unit.scalar, 0.01
    assert_in_delta '0 tempF'.unit.scalar, '255.37 degK'.unit.scalar, 0.01
    assert_in_delta '0 tempK'.unit.scalar, '0 degK'.unit.scalar, 0.01
    assert_in_delta '0 tempR'.unit.scalar, '0 degK'.unit.scalar, 0.01

    unit1 = Unit.new("37 degC")
    unit2 = unit1 >> "tempF"
    assert_in_delta 98.6, unit2.scalar, 0.1
    unit2 = unit1 >> "tempK"
    assert_in_delta 310.15, unit2.scalar, 0.01
    unit2 = unit1 >> "tempR"
    assert_in_delta 558.27, unit2.scalar, 0.01
    unit3 = Unit.new("1 J/degC")
    assert_in_delta 1, (unit3 >> "J/degK").scalar, 0.01
    
    unit1 = Unit.new("98.6 degF")
    unit2 = unit1 >> "tempC"
    assert_in_delta 37, unit2.scalar, 0.1
    unit2 = unit1 >> "tempK"
    assert_in_delta 310.15, unit2.scalar, 0.01
    unit2 = unit1 >> "tempR"
    assert_in_delta 558.27, unit2.scalar, 0.01
    unit3 = Unit.new("1 J/degC")
    assert_in_delta 1, (unit3 >> "J/degK").scalar, 0.01
    
    unit1 = Unit.new("310.15 degK")
    unit2 = unit1 >> "tempF"
    assert_in_delta 98.6, unit2.scalar, 0.1
    unit2 = unit1 >> "tempC"
    assert_in_delta 37, unit2.scalar, 0.01
    unit2 = unit1 >> "tempR"
    assert_in_delta 558.27, unit2.scalar, 0.01
    unit3 = Unit.new("1 J/degC")
    assert_in_delta 1, (unit3 >> "J/degK").scalar, 0.01
    
    unit1 = Unit.new("558.27 degR")
    unit2 = unit1 >> "tempC"
    assert_in_delta 37, unit2.scalar, 0.1
    unit2 = unit1 >> "tempK"
    assert_in_delta 310.15, unit2.scalar, 0.01
    unit2 = unit1 >> "tempF"
    assert_in_delta 98.6, unit2.scalar, 0.01
    assert_in_delta 558.27, unit1.to("tempR").scalar, 0.01
    unit3 = Unit.new("1 J/degC")
    assert_in_delta 1, (unit3 >> "J/degK").scalar, 0.01
    
    # round trip conversions
    unit1 = Unit "37 degC"
    unit2 = unit1 >> "degF" >> 'degK' >> 'degR' >> 'degC'
    assert_equal unit2, unit1

    unit1 = Unit "37 degC"
    unit2 = unit1 >> "tempF" >> 'tempK' >> 'tempR' >> 'tempC'
    assert_equal unit2, unit1
  end
  
  def test_feet
    unit1 = Unit.new("6'6\"")
    assert_in_delta 6.5, unit1.scalar, 0.01
  end
  
  def test_pounds
    unit1 = Unit.new("8 pounds, 8 ounces")
    assert_in_delta 8.5, unit1.scalar, 0.01
  end
  
  # these units are 'ambiguous' and could be mis-parsed
  def test_parse_tricky_units
    unit1 = Unit.new('1 mm')      #sometimes parsed as 'm*m'
    assert_equal ['<milli>','<meter>'], unit1.numerator
    unit2 = Unit.new('1 cd')      # could be a 'centi-day' instead of a candela
    assert_equal ['<candela>'], unit2.numerator
    unit3 = Unit.new('1 min')      # could be a 'milli-inch' instead of a minute
    assert_equal ['<minute>'], unit3.numerator
    unit4 = Unit.new('1 ft')      # could be a 'femto-ton' instead of a foot
    assert_equal ['<foot>'], unit4.numerator  
    unit5 = "1 atm".unit
    assert_equal ['<atm>'], unit5.numerator
    unit6 = "1 doz".unit
    assert_equal ['<dozen>'], unit6.numerator
  end
   
  def test_to_s
    unit1 = Unit.new("1")
    assert_equal "1", unit1.to_s
    unit2 = Unit.new("mm")
    assert_equal "1 mm", unit2.to_s
    assert_equal "0.04 in", unit2.to_s("%0.2f in")
    assert_equal "0.1 cm", unit2.to_s("cm")
    unit3 = Unit.new("1 mm")
    assert_equal "1 mm", unit3.to_s
    assert_equal "0.04 in", unit3.to_s("%0.2f in")
    unit4 = Unit.new("1 mm^2")
    assert_equal "1 mm^2", unit4.to_s
    unit5 = Unit.new("1 mm^2 s^-2")
    assert_equal "1 mm^2/s^2", unit5.to_s
    unit6= Unit.new("1 kg*m/s")
    assert_equal "1 kg*m/s", unit6.to_s
    unit7= Unit.new("1 1/m")
    assert_equal "1 1/m", unit7.to_s
    
  end
  
  def test_to_feet_inches
    unit1 = Unit.new("6'5\"")
    assert_equal "6'5\"", unit1.to_s(:ft)
    assert_raises(ArgumentError) {
      unit1 = Unit.new("1 kg")
      unit1.to_s(:ft)
    }
  end
  
  def test_to_lbs_oz
    unit1 = Unit.new("8 lbs 8 oz")
    assert_equal "8 lbs, 8 oz", unit1.to_s(:lbs)
    assert_raises(ArgumentError) {
      unit1 = Unit.new("1 m")
      unit1.to_s(:lbs)
    }
  end
  
  def test_add_units
    a = Unit.new("1 inchworm")
    assert_equal "1 inworm", a.to_s
  end
  
  def test_ideal_gas_law
    p = Unit "100 kPa"
    v = Unit "1 m^3"
    n = Unit "1 mole"
    r = Unit "8.31451 J/mol*degK"
    t = ((p*v)/(n*r)).to("tempF")
    assert_in_delta 21189.2,t.scalar, 0.1
  end
  
  
  def test_eliminate_terms
    a = ['<meter>','<meter>','<kelvin>','<second>']
    b = ['<meter>','<meter>','<second>']
    h = Unit.eliminate_terms(1,a,b)
    assert_equal ['<kelvin>'], h[:numerator]
  end
  
  def test_to_base_consistency
    a = "1 W*m/J*s".unit
    assert_equal a.signature, a.to_base.signature
  end
  
  def test_unit_roots
    unit1 = Unit "2 m*J*kg"
    unit2 = Unit "4 m^2*J^2*kg^2"
    unit3 = Unit "8 m^3*J^3*kg^3"
    assert_equal unit2**(1/2), unit1
    assert_equal unit3**(1/3), unit1
  end
  
  def test_inspect
    unit1 = Unit "1 mm"
    assert_equal "1 mm", unit1.inspect
    assert_not_equal "1.0 mm", unit1.inspect(:dump)
  end
  
  def test_to_f
    assert_equal 1, 1.unit.to_f
    assert_raises(RuntimeError) {
      assert_equal 1, "1 mm".unit.to_f
    }
  end
  
  def test_exponentiate_float2
    assert_equal "2 m".unit, "4 m^2".unit**(0.5) 
    assert_raises(ArgumentError) { "1 mm".unit**(2/3)}
    assert_raises(ArgumentError) { "1 mm".unit**("A")}
    
  end
  
  def test_range
    a = Unit "1 mm"
    b = Unit "3 mm"
    c = (a..b).to_a
    assert_equal ["1 mm".unit, "2 mm".unit, "3 mm".unit], c
  end
  
  def test_scientific
    a = Unit "1e6 cells"
    assert_equal 1e6, a.scalar
    assert_equal "cells", a.units
  end
  
  def test_uncertain
    if defined? Uncertain
      a = Uncertain.new(1,1)
      b = a.unit('mm')
      assert_equal b.to_s, '1 +/- 1 mm' 
    else
      fail "Can't test Uncertain Units unless 'Uncertain' gem is installed"
    end  
  end
  
  def test_format
    assert_equal "%0.2f" % "1 mm".unit, "1.00 mm" 
  end
  
  def test_bad_units
    assert_raises(ArgumentError) { '1 doohickey / thingamabob'.unit}
    assert_raises(ArgumentError) { '1 minimeter'.unit}
  end
  
  def test_currency
    assert_nothing_raised {a = "$1".unit}
  end
  
  def test_kind
    a = "1 mm".unit
    assert_equal a.kind, :length
  end
  
  def test_percent
      assert_nothing_raised {
       z = "1 percent".unit
        a = "1%".unit
        b = "0.01%".unit
      }
      a = '100 ml'.unit
      b = '50%'.unit
      c = a*b
      assert_equal '50 ml'.unit, c
  end
  
  def test_parse
    assert_raises(ArgumentError) { "3 s/s/ft".unit }
    assert_raises(ArgumentError) { "3 s**2|,s**2".unit }
    assert_raises(ArgumentError) { "3 s**2 4s s**2".unit }
    assert_raises(ArgumentError) { "3 s 5^6".unit }
    assert_raises(ArgumentError) { "".unit }
  end
  
  def test_time_conversions
    today = 'now'.to_time
    assert_equal today,@april_fools
    last_century = today - '150 years'.unit
    assert_equal last_century.to_date, '1856-04-01'.to_date
  end
  
  def test_coercion
    assert_nothing_raised { 1.0 * '1 mm'.unit}
    assert_nothing_raised { '1 mm'.unit * 1.0}
  end
  
  def test_zero
        assert_nothing_raised { Unit.new(0) }
  end
  
  def test_divide_results_in_unitless
    a = '10 mg/ml'.unit
    b = '10 mg/ml'.unit
    assert_equal a/b, 1
  end
end