add tests for download_datasets function

elephant/test/test_datasets.py

@@ -0,0 +1,35 @@
+import unittest
+import os
+from unittest.mock import patch
+from pathlib import Path
+import urllib
+
+from elephant.datasets import download_datasets
+
+
+class TestDownloadDatasets(unittest.TestCase):
+    @patch.dict(os.environ, {'ELEPHANT_DATA_LOCATION': '/valid/path'}, clear=True)
+    @patch('os.path.exists', return_value=True)
+    def test_valid_path(self, mock_exists):
+        repo_path = 'some/repo/path'
+        expected = Path('/valid/path/some/repo/path')
+        result = download_datasets(repo_path)
+        self.assertEqual(result, expected)
+
+    @patch.dict(os.environ, {'ELEPHANT_DATA_LOCATION': 'http://valid.url'}, clear=True)
+    @patch('os.path.exists', return_value=False)
+    def test_valid_url(self, mock_exists):
+        repo_path = 'some/repo/path'
+        self.assertRaises(urllib.error.URLError, download_datasets, repo_path)
+
+    @patch.dict(os.environ, {'ELEPHANT_DATA_LOCATION': 'invalid_path_or_url'}, clear=True)
+    @patch('os.path.exists', return_value=False)
+    def test_invalid_value(self, mock_exists):
+        repo_path = 'some/repo/path'
+        with self.assertRaises(ValueError) as cm:
+            download_datasets(repo_path)
+        self.assertIn("invalid_path_or_url", str(cm.exception))
+
+
+if __name__ == '__main__':
+    unittest.main()