old_contents: """ unit testing the helper functions """
  
  from exch.helpers import fixer
  
  def test_fixer_same_currency_code():
      """ when the same currency is base as well as target """
      assert fixer('USD', 'USD', 1) == 1.00
      assert fixer('INR', 'INR', 1) == 1.00
  
  def test_fixer_usd_to_inr():
      """ fixer_io base: USD, target: INR, on date 2017-05-12 """
      assert fixer('USD', 'INR', 1, date='2017-05-12') == round(64.307, 2)
  
  def test_fixer_usd_to_jpy():
      """ fixer_io base: USD, target: JPY, on date 2017-05-12 """
      assert fixer('USD', 'JPY', 1, date='2017-05-12') == round(113.85, 2)
  
  def test_fixer_gbp_to_php_value_99():
      """ fixer_io base: GBP, target: PHP, on date 2017-05-12, value: 99 """
      assert fixer('GBP', 'PHP', 99, date='2017-05-12') == round(63.942 * 99, 2)
  
  def test_fixer_inavlid_currency():
      """ when invalid currency is passed to fixer.io """
      assert fixer('USD', 'TTT', 1) == "Invalid currency"
      assert fixer('HHRR', 'TTT', 1) == "Invalid currency"
  
  # TODO: test for connection error
  
new_contents: """ unit testing the helper functions """
  
  from exch.helpers import fixer
  
  def test_fixer_same_currency_code():
      """ when the same currency is base as well as target """
      assert fixer('USD', 'USD', 1) == 1.00
      assert fixer('INR', 'INR', 1) == 1.00
  
  def test_fixer_usd_to_inr():
      """ fixer_io base: USD, target: INR, on date 2017-05-12 """
      assert fixer('USD', 'INR', 1, date='2017-05-12') == round(64.307, 2)
  
  def test_fixer_usd_to_jpy():
      """ fixer_io base: USD, target: JPY, on date 2017-05-12 """
      assert fixer('USD', 'JPY', 1, date='2017-05-12') == round(113.85, 2)
  
  def test_fixer_gbp_to_php_value_99():
      """ fixer_io base: GBP, target: PHP, on date 2017-05-12, value: 99 """
      assert fixer('GBP', 'PHP', 99, date='2017-05-12') == round(63.942 * 99, 2)
  
  def test_fixer_invalid_currency():
      """ when invalid currency is passed to fixer.io """
      assert fixer('USD', 'TTT', 1) == "Invalid currency"
      assert fixer('HHRR', 'TTT', 1) == "Invalid currency"
  
subject: fix typo in function name