Change multiple and default to inclusive with no defaults

homeassistant/data_entry_flow.py

@@ -918,8 +918,8 @@ class section:
     CONFIG_SCHEMA = vol.Schema(
         {
             vol.Optional("collapsed", default=False): bool,
-            vol.Optional("multiple", default=False): bool,
+            vol.Inclusive("multiple", "multiple"): bool,
-            vol.Optional("default", default=[]): list[Any],
+            vol.Inclusive("default", "multiple"): list[Any],
         },
     )
 

homeassistant/helpers/config_validation.py

@@ -1145,8 +1145,8 @@ def _custom_serializer(schema: Any, *, allow_section: bool) -> Any:
                 ),
             ),
             "expanded": not schema.options["collapsed"],
-            "multiple": schema.options["multiple"],
+            "multiple": schema.options.get("multiple"),
-            "default": schema.options["default"],
+            "default": schema.options.get("default"),
         }
 
     if isinstance(schema, multi_select):

tests/test_data_entry_flow.py

@@ -1020,9 +1020,69 @@ def test_section_in_serializer() -> None:
             {"name": "option_2", "required": True, "type": "integer"},
         ],
         "type": "expandable",
+        "multiple": None,
+        "default": None,
     }
 
 
+def test_section_multiple_in_serializer() -> None:
+    """Test section with multiple with custom_serializer."""
+    assert cv.custom_serializer(
+        data_entry_flow.section(
+            vol.Schema(
+                {
+                    vol.Optional("option_1", default=False): bool,
+                    vol.Required("option_2"): int,
+                }
+            ),
+            {"collapsed": False, "multiple": True, "default": [{True, 10}]},
+        )
+    ) == {
+        "expanded": True,
+        "schema": [
+            {"default": False, "name": "option_1", "optional": True, "type": "boolean"},
+            {"name": "option_2", "required": True, "type": "integer"},
+        ],
+        "type": "expandable",
+        "multiple": True,
+        "default": [
+            {
+                True,
+                10,
+            },
+        ],
+    }
+
+
+def test_section_multiple_and_default_inclusive_in_serializer() -> None:
+    """Test section with multiple missing default in custom_serializer."""
+    with pytest.raises(vol.MultipleInvalid):
+        cv.custom_serializer(
+            data_entry_flow.section(
+                vol.Schema(
+                    {
+                        vol.Optional("option_1", default=False): bool,
+                        vol.Required("option_2"): int,
+                    }
+                ),
+                {"collapsed": False, "multiple": None},
+            )
+        )
+
+    with pytest.raises(vol.MultipleInvalid):
+        cv.custom_serializer(
+            data_entry_flow.section(
+                vol.Schema(
+                    {
+                        vol.Optional("option_1", default=False): bool,
+                        vol.Required("option_2"): int,
+                    }
+                ),
+                {"collapsed": False, "default": []},
+            )
+        )
+
+
 def test_nested_section_in_serializer() -> None:
     """Test section with custom_serializer."""
     with pytest.raises(