From fc14b3e78979ae9daaf9744a97f98ab032c542a5 Mon Sep 17 00:00:00 2001
From: Mauricio Villegas <5780272+mauvilsa@users.noreply.github.com>
Date: Tue, 10 Sep 2024 07:48:06 +0200
Subject: [PATCH] For consistency add_subclass_arguments now sets default None
 instead of SUPPRESS (lightning#20103).

---
 CHANGELOG.rst                         | 10 ++++++++++
 jsonargparse/_signatures.py           |  4 ++--
 jsonargparse_tests/test_core.py       |  4 +---
 jsonargparse_tests/test_subclasses.py |  6 +++---
 4 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index b9ab9ff3..3cb38afa 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -12,6 +12,16 @@ The semantic versioning only considers the public API as described in
 paths are considered internals and can change in minor and patch releases.
 
 
+v4.33.0 (2024-09-??)
+--------------------
+
+Changed
+^^^^^^^
+- For consistency ``add_subclass_arguments`` now sets default ``None`` instead
+  of ``SUPPRESS`` (`lightning#20103
+  <https://github.com/Lightning-AI/pytorch-lightning/issue/20103>`__).
+
+
 v4.32.2 (2024-09-??)
 --------------------
 
diff --git a/jsonargparse/_signatures.py b/jsonargparse/_signatures.py
index 639adc62..807a8d4c 100644
--- a/jsonargparse/_signatures.py
+++ b/jsonargparse/_signatures.py
@@ -3,7 +3,7 @@
 import dataclasses
 import inspect
 import re
-from argparse import SUPPRESS, ArgumentParser
+from argparse import ArgumentParser
 from contextlib import suppress
 from typing import Any, Callable, List, Optional, Set, Tuple, Type, Union
 
@@ -549,7 +549,7 @@ def add_subclass_arguments(
             }
         )
         if "default" not in kwargs:
-            kwargs["default"] = SUPPRESS
+            kwargs["default"] = None
         self._add_signature_parameter(
             group, None, param, added_args, skip, sub_configs=True, instantiate=instantiate, **kwargs
         )
diff --git a/jsonargparse_tests/test_core.py b/jsonargparse_tests/test_core.py
index eb1b6766..d43655d8 100644
--- a/jsonargparse_tests/test_core.py
+++ b/jsonargparse_tests/test_core.py
@@ -760,9 +760,7 @@ def test_default_config_files(parser, subtests, tmp_cwd):
     with subtests.test("get_default"):
         assert parser.get_default("op1") == "from default config file"
         parser.add_subclass_arguments(Calendar, "cal")
-        with pytest.raises(KeyError) as ctx:
-            parser.get_default("cal")
-        ctx.match("does not specify a default")
+        assert parser.get_default("cal") is None
 
     with subtests.test("set invalid"):
         with pytest.raises(ValueError) as ctx:
diff --git a/jsonargparse_tests/test_subclasses.py b/jsonargparse_tests/test_subclasses.py
index 2297bff1..00bc4cc3 100644
--- a/jsonargparse_tests/test_subclasses.py
+++ b/jsonargparse_tests/test_subclasses.py
@@ -1338,9 +1338,9 @@ def test_add_subclass_required_group(parser):
 def test_add_subclass_not_required_group(parser):
     parser.add_subclass_arguments(Calendar, "cal", required=False)
     cfg = parser.parse_args([])
-    assert cfg == Namespace()
+    assert cfg == Namespace(cal=None)
     init = parser.instantiate_classes(cfg)
-    assert init == Namespace()
+    assert init == Namespace(cal=None)
 
 
 class ListUnionA:
@@ -1723,7 +1723,7 @@ def test_subclass_error_indentation_invalid_init_arg(parser):
       Given value: abc
     """
     ).strip()
-    expected = textwrap.indent(expected, "    ")
+    expected = textwrap.indent(expected, "        ")
     assert expected in err