UniqueArray Problem

Gemfile

source 'https://rubygems.org'

gem 'rspec', '2.11.0'

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    diff-lcs (1.1.3)
    rspec (2.11.0)
      rspec-core (~> 2.11.0)
      rspec-expectations (~> 2.11.0)
      rspec-mocks (~> 2.11.0)
    rspec-core (2.11.0)
    rspec-expectations (2.11.1)
      diff-lcs (~> 1.1.3)
    rspec-mocks (2.11.1)

PLATFORMS
  ruby

DEPENDENCIES
  rspec (= 2.11)

gistfile1.md

For this problem you will be creating a Ruby class which behaves exactly like an array but will store only numbers, will store them in the order they were added and when adding new elements will ignore any duplicates. In this way it functions like a Ruby hash object in that each key has to be unique.

Examples

Creating an array from another array. Notice that only the first occurrence of the number 2 is kept:

UniqueArray.new([1,2,0,6,2,11]) 
#=> [1,2,0,6,11]

Creating an array by adding one element at a time:

m = UniqueArray.new()

[1,2,0,6,2,11].each do |new_element|
  m.add(new_element)
end

puts m
#=> [1,2,0,6,11]

Submit your ruby file containing the class you wrote. Also submit a test file which demonstrates how your class functions. You'll get bonus points if your test file uses the rSpec testing framework! ;)

unique_array.rb

require 'set'

class UniqueArray < Set

  def initialize(input = [])
    super(verified_input input)
  end

  def to_s
    self.to_a.to_s
  end

  def add(element)
    self << element if is_num? element
  end

  private

  def is_num?(element)
    element.kind_of? Numeric
  end
  
  def verified_input(input)
    input.select {|e| e if is_num? e }
  end
end

unique_array_spec.rb

require './unique_array'

describe "UniqueArray" do
  specify "when created with no arguments, it is empty" do
    m = UniqueArray.new
    expect(m).to be_empty
  end

  context "when created with an array that has" do
    specify "no duplicates, it is equal to the input array" do
      no_duplicates = [1, 2, 3, 4, 5]
      m = UniqueArray.new no_duplicates
      expect(m.to_a).to eq(no_duplicates)
    end

    specify "many duplicates, it only includes unique values" do
      m = UniqueArray.new [1, 2, 3, 4, 5, 1, 5, 1]
      expect(m.to_a).to eq([1, 2, 3, 4, 5])
    end

    specify "non-numeric values, it only includes numeric values" do
      m = UniqueArray.new [4, "joe", "bob", 7]
      expect(m.to_a).to eq([4, 7])
    end
  end

  describe "#add" do
    it "accepts numeric input" do
      m = UniqueArray.new
      m.add 4
      expect(m.to_a).to eq([4])
    end

    it "rejects non-numeric input" do
      m = UniqueArray.new
      m.add('not a number')
      expect(m).to be_empty
    end

    it "allows uniq numbers to be appended" do
      m = UniqueArray.new [1,2,3]
      m.add 4
      expect(m.to_a).to eq([1, 2, 3, 4])
    end
  end
end