Add test to branch

testing/test_pluginmanager.py

@@ -380,3 +380,20 @@ class TestPytestPluginManagerBootstrapming(object):
         pytestpm.consider_preparse(["xyz", "-p", "no:abc"])
         l2 = pytestpm.get_plugins()
         assert 42 not in l2
+    
+    def test_plugin_prevent_register_stepwise_on_cacheprovider_unregister(self, pytestpm):
+        """ From PR #4304 : The only way to unregister a module is documented at
+        the end of https://docs.pytest.org/en/latest/plugins.html.
+        
+        When unregister cacheprovider, then unregister stepwise too
+        """
+        pytestpm.register(42, name="cacheprovider")
+        pytestpm.register(43, name="stepwise")
+        l1 = pytestpm.get_plugins()
+        assert 42 in l1
+        assert 43 in l1
+        pytestpm.consider_preparse(["xyz", "-p", "no:cacheprovider"])
+        l2 = pytestpm.get_plugins()
+        assert 42 not in l2
+        assert 43 not in l2
+