def test_extracts_more_than_one_col(self):
        ce = ColsExtractor([0, 2])
        features = ce.transform(self.X)

        expected = [
            [0, 2],
            [3, 5]
        ]

        self.assertTrue(np.array_equal(expected, features))
 def test_extracts_one_col(self):
     ce = ColsExtractor([1])
     self.assertEqual([[1], [4]], ce.transform(self.X))
    def test_extracts_and_flattens(self):
        ce = ColsExtractor([0], flat=True)
        features = ce.transform(self.X)

        expected = [0, 3]
        self.assertTrue(np.array_equal(expected, features))