main: args must be a list, not tuple

src/_pytest/config/__init__.py

@@ -233,13 +233,15 @@ def get_plugin_manager():
     return get_config().pluginmanager
 
 
-def _prepareconfig(args=None, plugins=None):
+def _prepareconfig(
+    args: Optional[Union[py.path.local, List[str]]] = None, plugins=None
+):
     if args is None:
         args = sys.argv[1:]
     elif isinstance(args, py.path.local):
         args = [str(args)]
-    elif not isinstance(args, (tuple, list)):
-        msg = "`args` parameter expected to be a list or tuple of strings, got: {!r} (type: {})"
+    elif not isinstance(args, list):
+        msg = "`args` parameter expected to be a list of strings, got: {!r} (type: {})"
         raise TypeError(msg.format(args, type(args)))
 
     config = get_config(args, plugins)

testing/acceptance_test.py

@@ -606,7 +606,7 @@ def test_equivalence_pytest_pytest(self):
 
     def test_invoke_with_invalid_type(self):
         with pytest.raises(
-            TypeError, match="expected to be a list or tuple of strings, got: '-h'"
+            TypeError, match="expected to be a list of strings, got: '-h'"
         ):
             pytest.main("-h")