Add placeholder tests for get_contents function

tests/get_contents_test.py

@@ -0,0 +1,22 @@
+# This file contains tests for `get_contents` which is responsible for
+# getting the download urls for the content files of the provided GitHub URL.
+
+import pytest
+import requests_mock
+
+from github_dlr.source import get_contents
+
+
+def test_get_contents_from_dir_success():
+    # When the provided link is a directory with sub-contents
+    # it should return all of it's contents as a list containing
+    # the data in dict.
+    # TODO: Write the tests
+    pass
+
+
+def test_get_content_from_file_success():
+    # When the provided link is a file object itself.
+    # it should return a dict instead of a list.
+    # TODO: Write the tests
+    pass