Flatten array in Ruby

README.md

That's a homebrewed flatten array method.

Tests

Run ruby flatten_spec.rb to make sure everything is working.

Minitest

I used ministest since that's a simple test and minitest is a built in lib.

flatten.rb

def flatten(array)
  new_array = []
  array.each do |element|
    if element.kind_of?(Array)
      new_array += flatten(element)
    else
      new_array << element
    end
  end
  new_array
end

flatten_spec.rb

require 'minitest/autorun'
require ('./flatten.rb')

describe "Flatten" do
  before do
    @simple_array = [1,2,3]
    @multiples_array = [[1,2,[3]],4]
    @complex_array = [1,2,[3,[4,5,[6,[7,[8, 9, 10, 11, [[], [12], [13], [[], [14]]]]]]]]]
  end

  describe "#flatten" do
    it "returns the passed array if is a simple array" do
      flatten_array = flatten(@simple_array)
      flatten_array.must_equal [1,2,3]
    end

    it "flattens an array recursively when array has array elements" do
      flatten_array = flatten(@multiples_array)
      flatten_array.must_equal [1,2,3,4]
    end

    it "flattens an array recursively on a complex array element" do
      flatten_array = flatten(@complex_array)
      flatten_array.must_equal [1,2,3,4,5,6,7,8,9,10,11,12,13,14]
    end
  end
end