text: """
  Homework 3-4 Part 2
  Cathy Jia
  """
  
  import unittest
  from dataframe import DF, COLS
  
  class TestDataframe(unittest.TestCase):
      """
      Unit tests for dataframe.py
      """
      def test_column_names(self):
          """
          Have the expected columns
          """
          for col in COLS:
              self.assertIn(col, DF.columns, "DataFrame doesn't have the expected column names.")
  
      def test_expected_type(self):
          """
          Values in the column are all of the expected type
          """
          for col in DF.columns:
              if col != 'quality':
                  self.assertEqual(str(DF[col].dtypes), 'float64')
              elif col == 'quality':
                  self.assertEqual(str(DF[col].dtypes), 'int64')
  
      def test_no_nan_values(self):
          """
          There are no nan values
          """
          self.assertEqual(DF.isnull().sum().sum(), 0)
  
      def test_at_least_onw_row(self):
          """
          The dataframe has at least one row
          """
          self.assertGreaterEqual(DF.shape[0], 1)
  
  SUITE = unittest.TestLoader().loadTestsFromTestCase(TestDataframe)
  unittest.TextTestRunner(verbosity=2).run(SUITE)
  