diff --git a/requirements-test.txt b/requirements-test.txt
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1,4 +1,5 @@
 pytest
+pytest-mock
 requests-mock
 hypothesis >= 3.11.0
 pre-commit
diff --git a/swh/core/db/common.py b/swh/core/db/common.py
--- a/swh/core/db/common.py
+++ b/swh/core/db/common.py
@@ -7,6 +7,19 @@
 import functools
 
 
+def remove_kwargs(names):
+    def decorator(f):
+        sig = inspect.signature(f)
+        params = sig.parameters
+        params = [param for param in params.values()
+                  if param.name not in names]
+        sig = sig.replace(parameters=params)
+        f.__signature__ = sig
+        return f
+
+    return decorator
+
+
 def apply_options(cursor, options):
     """Applies the given postgresql client options to the given cursor.
 
@@ -33,7 +46,8 @@
             raise ValueError(
                     'Use db_transaction_generator for generator functions.')
 
-        @functools.wraps(meth)
+        @remove_kwargs(['cur', 'db'])
+        @functools.wraps(meth, assigned=['cur', 'db'])
         def _meth(self, *args, **kwargs):
             if 'cur' in kwargs and kwargs['cur']:
                 cur = kwargs['cur']
@@ -67,6 +81,7 @@
             raise ValueError(
                     'Use db_transaction for non-generator functions.')
 
+        @remove_kwargs(['cur', 'db'])
         @functools.wraps(meth)
         def _meth(self, *args, **kwargs):
             if 'cur' in kwargs and kwargs['cur']:
diff --git a/swh/core/db/tests/test_db.py b/swh/core/db/tests/test_db.py
--- a/swh/core/db/tests/test_db.py
+++ b/swh/core/db/tests/test_db.py
@@ -3,15 +3,18 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+import inspect
 import os.path
 import tempfile
 import unittest
+from unittest.mock import Mock, MagicMock
 
 from hypothesis import strategies, given
 import psycopg2
 import pytest
 
 from swh.core.db import BaseDb
+from swh.core.db.common import db_transaction, db_transaction_generator
 from .db_testing import (
     SingleDbTestFixture, db_create, db_destroy, db_close,
 )
@@ -108,3 +111,112 @@
         items = [dict(zip(['i', 'txt', 'bytes'], item)) for item in data]
         with self.assertRaises(psycopg2.errors.NumericValueOutOfRange):
             self.db.copy_to(items, 'test_table', ['i', 'txt', 'bytes'])
+
+
+def test_db_transaction(mocker):
+    expected_cur = object()
+
+    called = False
+
+    class Storage:
+        @db_transaction()
+        def endpoint(self, cur=None, db=None):
+            nonlocal called
+            called = True
+            assert cur is expected_cur
+
+    storage = Storage()
+
+    # 'with storage.get_db().transaction() as cur:' should cause
+    # 'cur' to be 'expected_cur'
+    db_mock = Mock()
+    db_mock.transaction.return_value = MagicMock()
+    db_mock.transaction.return_value.__enter__.return_value = expected_cur
+    mocker.patch.object(
+        storage, 'get_db', return_value=db_mock, create=True)
+
+    put_db_mock = mocker.patch.object(
+        storage, 'put_db', create=True)
+
+    storage.endpoint()
+
+    assert called
+    put_db_mock.assert_called_once_with(db_mock)
+
+
+def test_db_transaction__with_generator():
+    with pytest.raises(ValueError, match='generator'):
+        class Storage:
+            @db_transaction()
+            def endpoint(self, cur=None, db=None):
+                yield None
+
+
+def test_db_transaction_signature():
+    """Checks db_transaction removes the 'cur' and 'db' arguments."""
+    def f(self, foo, *, bar=None):
+        pass
+    expected_sig = inspect.signature(f)
+
+    @db_transaction()
+    def g(self, foo, *, bar=None, db=None, cur=None):
+        pass
+
+    actual_sig = inspect.signature(g)
+
+    assert actual_sig == expected_sig
+
+
+def test_db_transaction_generator(mocker):
+    expected_cur = object()
+
+    called = False
+
+    class Storage:
+        @db_transaction_generator()
+        def endpoint(self, cur=None, db=None):
+            nonlocal called
+            called = True
+            assert cur is expected_cur
+            yield None
+
+    storage = Storage()
+
+    # 'with storage.get_db().transaction() as cur:' should cause
+    # 'cur' to be 'expected_cur'
+    db_mock = Mock()
+    db_mock.transaction.return_value = MagicMock()
+    db_mock.transaction.return_value.__enter__.return_value = expected_cur
+    mocker.patch.object(
+        storage, 'get_db', return_value=db_mock, create=True)
+
+    put_db_mock = mocker.patch.object(
+        storage, 'put_db', create=True)
+
+    list(storage.endpoint())
+
+    assert called
+    put_db_mock.assert_called_once_with(db_mock)
+
+
+def test_db_transaction_generator__with_nongenerator():
+    with pytest.raises(ValueError, match='generator'):
+        class Storage:
+            @db_transaction_generator()
+            def endpoint(self, cur=None, db=None):
+                pass
+
+
+def test_db_transaction_generator_signature():
+    """Checks db_transaction removes the 'cur' and 'db' arguments."""
+    def f(self, foo, *, bar=None):
+        pass
+    expected_sig = inspect.signature(f)
+
+    @db_transaction_generator()
+    def g(self, foo, *, bar=None, db=None, cur=None):
+        yield None
+
+    actual_sig = inspect.signature(g)
+
+    assert actual_sig == expected_sig