require 'minitest/autorun'

def word_median(word)
  half = word.length / 2

  case
  when word == '' then ''
  when word.length.odd? then word[half]
  else word[half - 1..half]
  end
end

describe 'word median' do
  it 'returns empty string when source string is empty' do
    assert word_median('') == ''
  end

  it 'returns middle character when word has odd length' do
    assert word_median('a') == 'a'
    assert word_median('foo') == 'o'
    assert word_median('never') == 'v'
    assert word_median('stackoverflow') == 'v'
  end

  it 'returns middle characters when word has even length' do
    assert word_median('ab') == 'ab'
    assert word_median('flower') == 'ow'
  end
end