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hobbits in holes and chipmunks in a phonebooth

21 May 2010 | 11:01 am by codeboxer

When writing unit tests, for unit/quantity measurements it is important to do the right thing. The rule is that you must test against either hobbits or chipmunks, in their appropriate quantities.

Also, there is such a thing as shaving yaks. I do it all day. :)

http://en.wiktionary.org/wiki/yak_shaving

Sample class with a unit test

12 December 2008 | 10:40 am by codeboxer

Also from a job interview a while back.

Here is the class that they gave me, which I extended -

class YPSet
#new and improved (sorry for the double email)
def initialize(*args)
@collect = []
args.each do |this|
@collect << this.to_i
end
@collect.sort!
@count = @collect.size
end

def average
sum = 0
@collect.each do |this|
sum+=this.to_f
end
(sum/@count)
end

def first_rec
@collect[0] ? @collect[0].to_i : nil
end

def lowest
first_rec
end

def highest
@collect[@count-1] ? @collect[@count-1].to_i : nil
end

def median
even_check=0
@collect.each do |this|
#loop to skip even method which is not importing properly
even_check = even_check==0 ? 1 : 0
end
is_even = even_check == 0 ? true : false
if is_even
#average median
half_position = (@count/2)
#first value
x1 = @collect[half_position-1]
#second value
x2 = @collect[half_position]
((x1+x2).to_f/2)
else
#single target
target_position = ((@count.to_i-1)/2) + 1
# value
@collect[target_position-1]
end
end

def average_dev
#return average deviation from main average per item
sum_of_deviations = 0
ave = self.average
@collect.each do |this|
sum_of_deviations += (this.to_f-ave).abs
end
sum_of_deviations/@count.to_i
end

def number_of_odds
count = 0
@collect.each do |this|
even_check = 0
for x in 1..this
#loop to skip even method (again)
even_check = even_check==0 ? 1 : 0
end
count += even_check
end
count
end

def number_of_evens
@count - number_of_odds
end

def partition(subdivisions)
#split into evenly sized partitions
single_part_size = (@count/subdivisions).to_i
new_array = []
cur_division = 1
x = 0
count_leftover = @count % subdivisions
original_leftover_count = count_leftover
while cur_division <= subdivisions
#test divisions
sub_array = []
while (x < ((single_part_size*cur_division) + (cur_division<=original_leftover_count && original_leftover_count>0) ? cur_division))
end

And the unit test I wrote for it -

require "test/unit"
require "yp_set"

class YPSetTest < Test::Unit::TestCase

def setup

end

def test_should_calculate_average
assert_equal 6, YPSet.new(8, 10, 2, 6, 4).average
assert_equal 5.5, YPSet.new(10, 11, 0, 1).average
end

# The median is the middle value in a set of values. If there are
# an even number of values, it should be the average of the two middle
# values
def test_should_calculate_median
assert_equal 6, YPSet.new(8, 10, 2, 6, 4).median
assert_equal 4.5, YPSet.new(10, 0, 1, 9, 8, 1).median
end

def test_should_calculate_with_string_args
assert_equal 2, YPSet.new(1, "2", 3, "2", 2).average
assert_equal 3, YPSet.new("7", "2", 3, "8", 2).median
end

def test_should_be_ordered_correctly
#added per point #3
assert_equal 2, YPSet.new(9, "11", 2, "2", 6).first_rec
end

def test_average_dev
#added per point #4
assert_equal 2, YPSet.new(1, 1, 2, 2, 3, 9).average_dev
end

def test_lowest_and_highest
#added per point #4
assert_operator YPSet.new(99, 44, 33).lowest, "<", YPSet.new(33, 99, 44).highest
end

def test_number_of_evens
#added per point #4 - no need to test odds as they use the same function
assert_equal 6, YPSet.new(99, 44, 33, 2, 6, 8, 9, 12, 14).number_of_evens
end

def test_should_split_into_evenly_sized_subsets
values = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]

subsets = YPSet.new(*values).partition(3)
assert_equal 3, subsets.length
subsets.each do |subset|
assert_equal 5, subset.length
end
assert_equal values.length, subsets.flatten.length

values << 16
subsets = YPSet.new(*values).partition(3)
assert_equal 3, subsets.length
subsets.each do |subset|
assert_in_delta 5, subset.length, 1
end
assert_equal values.length, subsets.flatten.length
end
end

Good times!Original post blogged on codeboxer.com.