diff --git a/pyproject.toml b/pyproject.toml
index 28154e6..6f9040d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -12,13 +12,13 @@ keywords = ["scopes"]
 authors = [{name = "Helmut Merz", email = "helmutm@cy55.de"}]
 
 dependencies = [
+	"SQLAlchemy",
 ]
 
 [project.optional-dependencies]
 postgres = [
-	"transaction",
 	"psycopg[binary]",
-	"SQLAlchemy",
+	"transaction",
 	"zope.sqlalchemy",
 ]
 app = ["python-dotenv", "zope.publisher", "zope.traversing"]
diff --git a/scopes/storage/db/postgres.py b/scopes/storage/db/postgres.py
index 55e49b8..beaa34a 100644
--- a/scopes/storage/db/postgres.py
+++ b/scopes/storage/db/postgres.py
@@ -22,6 +22,7 @@ def getEngine(dbtype, dbname, user, pw, host='localhost', port=5432, **kw):
 def commit(conn):
     transaction.commit()
 
+# patch `common` module
 import scopes.storage.common
 scopes.storage.common.IdType = BigInteger
 scopes.storage.common.JsonType = JSONB
diff --git a/tests/test_storage.py b/tests/test_storage.py
index 59598bd..bea9d1f 100644
--- a/tests/test_storage.py
+++ b/tests/test_storage.py
@@ -5,7 +5,6 @@
 import config
 
 from datetime import datetime
-import transaction
 import unittest
 
 import scopes.storage.common
@@ -19,72 +18,16 @@ scopes.storage.common.Session = sessionFactory(engine)
 
 storage = Storage(schema=config.dbschema)
 
+import tlib
 
 class Test(unittest.TestCase):
     "Basic tests for the cco.storage package."
 
     def test_001_tracking(self):
-        storage.dropTable('tracks')
-        tracks = storage.create(tracking.Container)
-
-        tr01 = tracking.Track('t01', 'john')
-        tr01.update(dict(activity='testing'))
-        self.assertEqual(tr01.head, {'taskId': 't01', 'userName': 'john'})
-        self.assertEqual(tr01.taskId, 't01')
-        self.assertEqual(tr01.userName, 'john')
-
-        self.assertTrue(tracks.getTable() is not None)
-
-        trid01 = tracks.save(tr01)
-        self.assertTrue(trid01 > 0)
-
-        tr01a = tracks.get(trid01)
-        self.assertEqual(tr01a.head, tr01.head)
-        self.assertEqual(tr01a.trackId, trid01)
-        self.assertEqual(tr01a.data.get('activity'), 'testing')
-
-        tr01a.update(dict(text='Set up unit tests.'))
-        tr01a.timeStamp = None
-        self.assertTrue(tracks.save(tr01a) > 0)
-
-        tr01b = tracks.queryLast(taskId='t01')
-        self.assertEqual(tr01b.head, tr01.head)
-        self.assertNotEqual(tr01b.trackId, trid01)
-        self.assertEqual(tr01b.data.get('activity'), 'testing')
-
-        tr02 = tracking.Track('t02', 'jim', trackId=31, timeStamp=datetime(2023, 11, 30),
-                            data=dict(activity='concept'))
-        trid02 = tracks.upsert(tr02)
-        self.assertEqual(trid02, 31)
-        self.assertEqual(tr02.uid, 'rec-31')
-        tr02.trackId = trid01
-        trid021 = tracks.upsert(tr02)
-        self.assertEqual(trid021, trid01)
-        self.assertEqual(tr02.uid, 'rec-' + str(trid01))
-
-        tr03 = storage.getItem('rec-31')
-        self.assertEqual(tr03.trackId, 31)
-
-        n = tracks.remove(31)
-        self.assertEqual(n, 1)
-        self.assertEqual(tracks.get(31), None)
-
-        commit(storage.session)
+        tlib.test_tracking(self, storage)
 
     def test_002_folder(self):
-        storage.dropTable('folders')
-        root = folder.Root(storage)
-        self.assertEqual(list(root.keys()), [])
-        root['top'] = folder.Folder()
-        self.assertEqual(list(root.keys()), ['top'])
-        top = root['top']
-        top['child1'] = folder.Folder(data=dict(title='First Child'))
-        self.assertEqual(list(top.keys()), ['child1'])
-        ch1 = top['child1']
-        self.assertEqual(ch1.parent, top.rid)
-        assert list(top.keys()) == ['child1']
-
-        commit(storage.session)
+        tlib.test_folder(self, storage)
 
 def suite():
     return unittest.TestSuite((
diff --git a/tests/tlib.py b/tests/tlib.py
new file mode 100644
index 0000000..00fa6d7
--- /dev/null
+++ b/tests/tlib.py
@@ -0,0 +1,72 @@
+"""The real test implementations"""
+
+
+from datetime import datetime
+from scopes.storage import folder, tracking
+from scopes.storage.common import commit
+
+
+def test_tracking(self, storage):
+        storage.dropTable('tracks')
+        tracks = storage.create(tracking.Container)
+
+        tr01 = tracking.Track('t01', 'john')
+        tr01.update(dict(activity='testing'))
+        self.assertEqual(tr01.head, {'taskId': 't01', 'userName': 'john'})
+        self.assertEqual(tr01.taskId, 't01')
+        self.assertEqual(tr01.userName, 'john')
+
+        self.assertTrue(tracks.getTable() is not None)
+
+        trid01 = tracks.save(tr01)
+        self.assertTrue(trid01 > 0)
+
+        tr01a = tracks.get(trid01)
+        self.assertEqual(tr01a.head, tr01.head)
+        self.assertEqual(tr01a.trackId, trid01)
+        self.assertEqual(tr01a.data.get('activity'), 'testing')
+
+        tr01a.update(dict(text='Set up unit tests.'))
+        tr01a.timeStamp = None
+        self.assertTrue(tracks.save(tr01a) > 0)
+
+        tr01b = tracks.queryLast(taskId='t01')
+        self.assertEqual(tr01b.head, tr01.head)
+        self.assertNotEqual(tr01b.trackId, trid01)
+        self.assertEqual(tr01b.data.get('activity'), 'testing')
+
+        tr02 = tracking.Track('t02', 'jim', trackId=31, timeStamp=datetime(2023, 11, 30),
+                            data=dict(activity='concept'))
+        trid02 = tracks.upsert(tr02)
+        self.assertEqual(trid02, 31)
+        self.assertEqual(tr02.uid, 'rec-31')
+        tr02.trackId = trid01
+        trid021 = tracks.upsert(tr02)
+        self.assertEqual(trid021, trid01)
+        self.assertEqual(tr02.uid, 'rec-' + str(trid01))
+
+        tr03 = storage.getItem('rec-31')
+        self.assertEqual(tr03.trackId, 31)
+
+        n = tracks.remove(31)
+        self.assertEqual(n, 1)
+        self.assertEqual(tracks.get(31), None)
+
+        commit(storage.session)
+
+
+def test_folder(self, storage):
+        storage.dropTable('folders')
+        root = folder.Root(storage)
+        self.assertEqual(list(root.keys()), [])
+        root['top'] = folder.Folder()
+        self.assertEqual(list(root.keys()), ['top'])
+        top = root['top']
+        top['child1'] = folder.Folder(data=dict(title='First Child'))
+        self.assertEqual(list(top.keys()), ['child1'])
+        ch1 = top['child1']
+        self.assertEqual(ch1.parent, top.rid)
+        self.assertEqual(list(top.keys()), ['child1'])
+
+        commit(storage.session)
+