diff --git a/setup.py b/setup.py
index d871aa1e9e..a2244885ab 100755
--- a/setup.py
+++ b/setup.py
@@ -148,13 +148,13 @@ setup(name=name,
     license='GPL-3',
     python_requires='>=3.7',
     install_requires=requires,
+    extras_require={
+        'test': tests_require,
+        },
     dependency_links=dependency_links,
     zip_safe=False,
     entry_points="""
     [trytond.modules]
     purchase_product_quantity = trytond.modules.purchase_product_quantity
     """,  # noqa: E501
-    test_suite='tests',
-    test_loader='trytond.test_loader:Loader',
-    tests_require=tests_require,
     )
diff --git a/tests/__init__.py b/tests/__init__.py
index c06be4cc5e..4effdfa4a2 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -1,9 +1,2 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
-
-try:
-    from trytond.modules.purchase_product_quantity.tests.test_purchase_product_quantity import suite  # noqa: E501, isort: skip
-except ImportError:
-    from .test_purchase_product_quantity import suite
-
-__all__ = ['suite']
diff --git a/tests/test_module.py b/tests/test_module.py
new file mode 100644
index 0000000000..ee04672d88
--- /dev/null
+++ b/tests/test_module.py
@@ -0,0 +1,12 @@
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
+
+from trytond.tests.test_tryton import ModuleTestCase
+
+
+class PurchaseProductQuantityTestCase(ModuleTestCase):
+    'Test Purchase Product Quantity module'
+    module = 'purchase_product_quantity'
+
+
+del ModuleTestCase
diff --git a/tests/test_purchase_product_quantity.py b/tests/test_purchase_product_quantity.py
deleted file mode 100644
index a456815eac..0000000000
--- a/tests/test_purchase_product_quantity.py
+++ /dev/null
@@ -1,25 +0,0 @@
-# This file is part of Tryton.  The COPYRIGHT file at the top level of
-# this repository contains the full copyright notices and license terms.
-import doctest
-import unittest
-
-from trytond.tests.test_tryton import (
-    ModuleTestCase, doctest_checker, doctest_teardown)
-from trytond.tests.test_tryton import suite as test_suite
-
-
-class PurchaseProductQuantityTestCase(ModuleTestCase):
-    'Test Purchase Product Quantity module'
-    module = 'purchase_product_quantity'
-
-
-def suite():
-    suite = test_suite()
-    suite.addTests(unittest.TestLoader().loadTestsFromTestCase(
-            PurchaseProductQuantityTestCase))
-    suite.addTests(doctest.DocFileSuite(
-            'scenario_purchase_product_quantity.rst',
-            tearDown=doctest_teardown, encoding='utf-8',
-            checker=doctest_checker,
-            optionflags=doctest.REPORT_ONLY_FIRST_FAILURE))
-    return suite
diff --git a/tests/test_scenario.py b/tests/test_scenario.py
new file mode 100644
index 0000000000..c80e682a7f
--- /dev/null
+++ b/tests/test_scenario.py
@@ -0,0 +1,22 @@
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
+
+import doctest
+import glob
+import os
+
+from trytond.tests.test_tryton import doctest_checker, doctest_teardown
+
+
+def load_tests(loader, tests, pattern):
+    cwd = os.getcwd()
+    try:
+        os.chdir(os.path.dirname(__file__))
+        for scenario in glob.glob('*.rst'):
+            tests.addTests(doctest.DocFileSuite(
+                    scenario, tearDown=doctest_teardown, encoding='utf-8',
+                    checker=doctest_checker,
+                    optionflags=doctest.REPORT_ONLY_FIRST_FAILURE))
+    finally:
+        os.chdir(cwd)
+    return tests
diff --git a/tox.ini b/tox.ini
index 05543368fd..ccf3a1260c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,8 +2,9 @@
 envlist = {py37,py38,py39,py310}-{sqlite,postgresql}
 
 [testenv]
+extras = test
 commands =
-    coverage run --include=.*/purchase_product_quantity/* setup.py test
+    coverage run --include=.*/purchase_product_quantity/* -m unittest discover -s tests
     coverage report --include=.*/purchase_product_quantity/* --omit=*/tests/*
 deps =
     coverage