[FIX] some unittests are actually integration tests

[jcapels]

[FIX] some unittests are actually integration tests

For instance:

class TestEnsembles(TestCase):

    def setUp(self) -> None:
        self.data_path = os.path.join(TEST_DIR, 'data')

        dataset = os.path.join(self.data_path, "dataset_sweet_3d_balanced.sdf")
        loader = SDFLoader(dataset,
                           labels_fields='_SWEET')

        self.binary_dataset = loader.create_dataset()

        dataset = loader.create_dataset()
        splitter = SingletaskStratifiedSplitter()
        MorganFingerprint().featurize(dataset)
        self.train_dataset, self.test_dataset = splitter.train_test_split(dataset) 

This test is using the components SDFLoader, SingletaskStratifiedSplitter, and MorganFingerprint.

We should be mocking these methods in the unittests.