diff --git a/swh/loader/base/tests/test_download.py b/swh/loader/base/tests/test_download.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/base/tests/test_download.py
@@ -0,0 +1,73 @@
+# Copyright (C) 2019 The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import requests_mock
+
+
+class TestIf_Modified_Since():
+
+    def test_filter_package_versions():
+        pass
+
+    def test_invalid_request():
+        pass
+
+
+class TestcompareField():
+    tarballs = []
+
+    def check_compare_field(self):
+        """Check if the `compare_field` variable is declared
+        """
+        fl = self.get_fl()
+        if fl.compare_field == ("""Field used to identify if the package
+                        version is previously archived"""):
+            assert False
+
+    def test_filter_package_versions(self):
+        """
+
+        """
+        # test for no known version
+        fl = self.get_fl()
+        filtered_tarballs = fl.filter_package_versions(self.tarballs, None)
+        assert filtered_tarballs == self.tarballs
+
+        known_versions = {}
+        # test with one known version
+        # Assuming first tarball is already known
+        key = fl.compare_field
+        known_tarball_key = self.tarballs[0][key]
+        known_versions[known_tarball_key] = 'some_revision_id'
+        filtered_tarballs = fl.filter_package_versions(self.tarballs,
+                                                       known_versions)
+        # one tarball removed
+        assert len(filtered_tarballs) == (len(self.tarballs) - 1)
+
+        # Check if the know tarball is present in filtered tarballs
+        for tarball in filtered_tarballs:
+            if known_tarball_key in tarball:
+                assert False
+
+        # if all versions are known
+        for tarball in self.tarballs:
+            known_versions[tarball[key]] = 'some_revision_id'
+
+        filtered_tarballs = fl.filter_package_versions(self.tarballs,
+                                                       known_versions)
+        assert filtered_tarballs == []
+
+    @requests_mock.Mocker()
+    def test_invalid_request(self, http_mocker):
+        """
+
+        """
+        for tarball in self.tarballs:
+            http_mocker.get(tarball['url'], text='Not Found', status_code=404)
+
+        fl = self.get_fl()
+        generator = fl.prepare_package_versions(self.tarballs)
+        ll = [data for data in generator]
+        assert ll == []
diff --git a/swh/loader/base/tests/test_loader.py b/swh/loader/base/tests/test_loader.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/base/tests/test_loader.py
@@ -0,0 +1,60 @@
+# Copyright (C) 2019 The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+
+class TestLoader():
+
+    expected_revision = {}
+
+    def get_fl(self):
+        pass
+
+    def get_response(self):
+        """Call convert_to_standard_format() and pass the output
+
+        """
+        pass
+
+    def test_convert_to_standard_format(self):
+        """Test required field in `convert_to_standard_format()` output
+        """
+
+        package_details = self.get_response()
+        # Check for required field in output of convert_to_standard_format()
+        for key in ['name', 'origin_url', 'tarballs']:
+            if key not in package_details:
+                assert False
+
+        # Check for `url` key in tarballs key
+        for package in package_details['tarballs']:
+            if 'url' not in package:
+                assert False
+
+    def test_required_variable(self):
+        """Test if the required variable is declared in the loader class
+
+        """
+        fl = self.get_fl()
+        self.assertNotEqual(fl.loader_name, 'Name of the package manager')
+        self.assertNotEqual(fl.class_name, 'Name of the loader class')
+
+    def test_download_generate_hash(self):
+        """Test store file
+            Make me
+
+        """
+        pass
+
+    def test_first_visit(self):
+        """
+
+        """
+        pass
+
+    def test_second_visit(self):
+        """
+
+        """
+        pass
diff --git a/swh/loader/base/tests/test_revision.py b/swh/loader/base/tests/test_revision.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/base/tests/test_revision.py
@@ -0,0 +1,44 @@
+# Copyright (C) 2015-2018  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+'''
+from unittest.mock import patch
+
+from swh.loader.base import build_revision as build
+
+# Under construction
+
+
+class TestBuild_Revision():
+
+    expected_revision = {}
+
+    @patch('swh.loader.base.build_revision.directory')
+    def test_compute_revision(self, mock_directory):
+        package_source_data = {}
+        mock_directory.return_value = 'some-other-time'
+        actual_revision = build.compute_revision('/some/path',
+                                                 package_source_data)
+        # make me
+        expected_revision = {
+            'date': {
+                'timestamp': 'some-other-time',
+                'offset': build.UTC_OFFSET,
+            },
+            'committer_date': {
+                'timestamp': 'some-other-time',
+                'offset': build.UTC_OFFSET,
+            },
+            'author': build.SWH_PERSON,
+            'committer': build.SWH_PERSON,
+            'type': build.REVISION_TYPE,
+            'message': build.REVISION_MESSAGE,
+            'synthetic': True,
+        }
+
+        # then
+        self.assertEqual(actual_revision, expected_revision)
+
+        mock_directory.assert_called_once_with('/some/path')
+'''