red_green_refactor_code_tests_pitfall.rb

# Example for https://twitter.com/jessetrimble/status/910940206924050432

def test_matches_fixture_document
  (1..3).each do |row_number|
    expected_value = fixture_spreadsheet.cell(row, "A")
    assert_equal get_value_from_db, expected_value
  end
end

###### Refactored to:

class FixtureDocument
  def each_row(&block)
    (1..3).each do |row_number|
      value = fixture_spreadsheet.cell(row_number, "A")
      # Whoops, forgot to: yield(value)
    end
  end
end

def test_matches_fixture_document
  FixtureDocument.each_row do |expected_value|
    assert_equal get_value_from_db, expected_value
  end
end

# In the above example, the test is refactored to pull the details of what the fixture document is and how it's
# structured away from the tests, which is a good thing, but since we forgot to yield in our refactor, no assertions are
# ran, so there's no chance for the spec to fail!