diff --git a/swh/storage/tests/test_converters.py b/swh/storage/tests/test_converters.py
--- a/swh/storage/tests/test_converters.py
+++ b/swh/storage/tests/test_converters.py
@@ -3,158 +3,156 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-import unittest
-
 from swh.storage import converters
 
 
-class TestConverters(unittest.TestCase):
-    def setUp(self):
-        self.maxDiff = None
-
-    def test_date_to_db(self):
-        date_to_db = converters.date_to_db
-        assert date_to_db(None) == {
-            "timestamp": None, "offset": 0, "neg_utc_offset": None}
-
-        assert date_to_db({
-            "timestamp": 1234567890,
-            "offset": 120,
-            "negative_utc": False,
-        }) == {
-            "timestamp": "2009-02-13T23:31:30+00:00",
-            "offset": 120,
-            "neg_utc_offset": False,
-        }
-
-        assert date_to_db({
-            "timestamp": 1123456789,
-            "offset": 0,
-            "negative_utc": True,
-        }) == {
-            "timestamp": "2005-08-07T23:19:49+00:00",
-            "offset": 0,
-            "neg_utc_offset": True,
-        }
-
-        assert date_to_db({
-            "timestamp": 1234567890,
-            "offset": 42,
-            "negative_utc": False,
-        }) == {
-            "timestamp": "2009-02-13T23:31:30+00:00",
-            "offset": 42,
-            "neg_utc_offset": False,
-        }
-
-        assert date_to_db({
-            "timestamp": 1634366813,
-            "offset": -120,
-            "negative_utc": False,
-        }) == {
-            "timestamp": "2021-10-16T06:46:53+00:00",
-            "offset": -120,
-            "neg_utc_offset": False,
-        }
-
-    def test_db_to_author(self):
-        # when
-        actual_author = converters.db_to_author(
-            b'fullname', b'name', b'email')
-
-        # then
-        self.assertEqual(actual_author, {
-            'fullname': b'fullname',
-            'name': b'name',
-            'email': b'email',
-        })
-
-    def test_db_to_revision(self):
-        # when
-        actual_revision = converters.db_to_revision({
-            'id': 'revision-id',
-            'date': None,
-            'date_offset': None,
-            'date_neg_utc_offset': None,
-            'committer_date': None,
-            'committer_date_offset': None,
-            'committer_date_neg_utc_offset': None,
-            'type': 'rev',
-            'directory': b'dir-sha1',
-            'message': b'commit message',
-            'author_fullname': b'auth-fullname',
-            'author_name': b'auth-name',
-            'author_email': b'auth-email',
-            'committer_fullname': b'comm-fullname',
-            'committer_name': b'comm-name',
-            'committer_email': b'comm-email',
-            'metadata': {},
-            'synthetic': False,
-            'parents': [123, 456]
-        })
-
-        # then
-        self.assertEqual(actual_revision, {
-            'id': 'revision-id',
-            'author': {
-                'fullname': b'auth-fullname',
-                'name': b'auth-name',
-                'email': b'auth-email',
-            },
-            'date': None,
-            'committer': {
-                'fullname': b'comm-fullname',
-                'name': b'comm-name',
-                'email': b'comm-email',
-            },
-            'committer_date': None,
-            'type': 'rev',
-            'directory': b'dir-sha1',
-            'message': b'commit message',
-            'metadata': {},
-            'synthetic': False,
-            'parents': [123, 456],
-        })
-
-    def test_db_to_release(self):
-        # when
-        actual_release = converters.db_to_release({
-            'id': b'release-id',
-            'target': b'revision-id',
-            'target_type': 'revision',
-            'date': None,
-            'date_offset': None,
-            'date_neg_utc_offset': None,
-            'name': b'release-name',
-            'comment': b'release comment',
-            'synthetic': True,
-            'author_fullname': b'auth-fullname',
-            'author_name': b'auth-name',
-            'author_email': b'auth-email',
-        })
-
-        # then
-        self.assertEqual(actual_release, {
-            'author': {
-                'fullname': b'auth-fullname',
-                'name': b'auth-name',
-                'email': b'auth-email',
-            },
-            'date': None,
-            'id': b'release-id',
-            'name': b'release-name',
-            'message': b'release comment',
-            'synthetic': True,
-            'target': b'revision-id',
-            'target_type': 'revision'
-        })
-
-    def test_db_to_git_headers(self):
-        raw_data = [
-            ['gpgsig', b'garbage\x89a\x43b\x14'],
-            ['extra', [b'fo\\\\\\o', b'bar\\', b'inval\\\\\x99id']],
-        ]
-
-        db_data = converters.git_headers_to_db(raw_data)
-        loop = converters.db_to_git_headers(db_data)
-        self.assertEqual(raw_data, loop)
+def test_date_to_db():
+    date_to_db = converters.date_to_db
+    assert date_to_db(None) == {
+        "timestamp": None, "offset": 0, "neg_utc_offset": None}
+
+    assert date_to_db({
+        "timestamp": 1234567890,
+        "offset": 120,
+        "negative_utc": False,
+    }) == {
+        "timestamp": "2009-02-13T23:31:30+00:00",
+        "offset": 120,
+        "neg_utc_offset": False,
+    }
+
+    assert date_to_db({
+        "timestamp": 1123456789,
+        "offset": 0,
+        "negative_utc": True,
+    }) == {
+        "timestamp": "2005-08-07T23:19:49+00:00",
+        "offset": 0,
+        "neg_utc_offset": True,
+    }
+
+    assert date_to_db({
+        "timestamp": 1234567890,
+        "offset": 42,
+        "negative_utc": False,
+    }) == {
+        "timestamp": "2009-02-13T23:31:30+00:00",
+        "offset": 42,
+        "neg_utc_offset": False,
+    }
+
+    assert date_to_db({
+        "timestamp": 1634366813,
+        "offset": -120,
+        "negative_utc": False,
+    }) == {
+        "timestamp": "2021-10-16T06:46:53+00:00",
+        "offset": -120,
+        "neg_utc_offset": False,
+    }
+
+
+def test_db_to_author():
+    # when
+    actual_author = converters.db_to_author(
+        b'fullname', b'name', b'email')
+
+    # then
+    assert actual_author == {
+        'fullname': b'fullname',
+        'name': b'name',
+        'email': b'email',
+    }
+
+
+def test_db_to_revision():
+    # when
+    actual_revision = converters.db_to_revision({
+        'id': 'revision-id',
+        'date': None,
+        'date_offset': None,
+        'date_neg_utc_offset': None,
+        'committer_date': None,
+        'committer_date_offset': None,
+        'committer_date_neg_utc_offset': None,
+        'type': 'rev',
+        'directory': b'dir-sha1',
+        'message': b'commit message',
+        'author_fullname': b'auth-fullname',
+        'author_name': b'auth-name',
+        'author_email': b'auth-email',
+        'committer_fullname': b'comm-fullname',
+        'committer_name': b'comm-name',
+        'committer_email': b'comm-email',
+        'metadata': {},
+        'synthetic': False,
+        'parents': [123, 456]
+    })
+
+    # then
+    assert actual_revision == {
+        'id': 'revision-id',
+        'author': {
+            'fullname': b'auth-fullname',
+            'name': b'auth-name',
+            'email': b'auth-email',
+        },
+        'date': None,
+        'committer': {
+            'fullname': b'comm-fullname',
+            'name': b'comm-name',
+            'email': b'comm-email',
+        },
+        'committer_date': None,
+        'type': 'rev',
+        'directory': b'dir-sha1',
+        'message': b'commit message',
+        'metadata': {},
+        'synthetic': False,
+        'parents': [123, 456],
+    }
+
+
+def test_db_to_release():
+    # when
+    actual_release = converters.db_to_release({
+        'id': b'release-id',
+        'target': b'revision-id',
+        'target_type': 'revision',
+        'date': None,
+        'date_offset': None,
+        'date_neg_utc_offset': None,
+        'name': b'release-name',
+        'comment': b'release comment',
+        'synthetic': True,
+        'author_fullname': b'auth-fullname',
+        'author_name': b'auth-name',
+        'author_email': b'auth-email',
+    })
+
+    # then
+    assert actual_release == {
+        'author': {
+            'fullname': b'auth-fullname',
+            'name': b'auth-name',
+            'email': b'auth-email',
+        },
+        'date': None,
+        'id': b'release-id',
+        'name': b'release-name',
+        'message': b'release comment',
+        'synthetic': True,
+        'target': b'revision-id',
+        'target_type': 'revision'
+    }
+
+
+def test_db_to_git_headers():
+    raw_data = [
+        ['gpgsig', b'garbage\x89a\x43b\x14'],
+        ['extra', [b'fo\\\\\\o', b'bar\\', b'inval\\\\\x99id']],
+    ]
+
+    db_data = converters.git_headers_to_db(raw_data)
+    loop = converters.db_to_git_headers(db_data)
+    assert raw_data == loop