Add test to reproduce issue #276

Signed-off-by: Fabrice Normandin <normandf@mila.quebec>

test/subgroups/test_issue_276.py

@@ -0,0 +1,81 @@
+from pathlib import Path
+import shlex
+import pytest
+import yaml
+from dataclasses import dataclass
+from simple_parsing import subgroups, ArgumentParser
+from simple_parsing.wrappers.field_wrapper import (
+    ArgumentGenerationMode,
+    DashVariant,
+    NestedMode,
+)
+
+from simple_parsing.helpers.serialization.serializable import to_dict
+
+
+@dataclass
+class A:
+    a: int = 0
+
+
+@dataclass
+class B1(A):
+    b: float = 1
+
+
+@dataclass
+class B2(A):
+    b: float = 2
+
+
+@dataclass
+class C:
+    c: A = subgroups(
+        {
+            "b1": B1,
+            "b2": B2,
+        },
+        default="b1",
+    )
+
+
+@pytest.mark.parametrize(
+    ("argv", "expected", "save_dc_types_in_config"),
+    [
+        pytest.param(
+            "",
+            C(c=B2(a=0, b=1)),
+            True,
+            marks=pytest.mark.xfail(strict=True, raises=AssertionError),
+        ),
+        pytest.param(
+            "--c.a=1",
+            C(c=B2(a=1, b=1)),
+            True,
+            marks=pytest.mark.xfail(strict=True, raises=AssertionError),
+        ),
+        pytest.param(
+            "--c=b1",
+            C(c=B1(a=0, b=1)),
+            True,
+            marks=pytest.mark.xfail(strict=True, raises=RuntimeError),
+        ),
+    ],
+)
+def test_reproduce_issue(tmp_path: Path, argv: str, expected: C, save_dc_types_in_config: bool):
+    """Test for https://github.com/lebrice/SimpleParsing/issues/276."""
+    config_path = tmp_path / "config.yaml"
+    config_contents = to_dict(C(c=B2(a=0, b=1)), save_dc_types=save_dc_types_in_config)
+    with open(config_path, "w") as f:
+        yaml.dump(config_contents, f, indent=4)
+
+    parser = ArgumentParser(
+        argument_generation_mode=ArgumentGenerationMode.NESTED,
+        nested_mode=NestedMode.WITHOUT_ROOT,
+        add_option_string_dash_variants=DashVariant.UNDERSCORE_AND_DASH,
+        config_path=config_path,
+    )
+    parser.add_arguments(C, dest="config")
+    args = parser.parse_args(shlex.split(argv))
+    config: C = args.config
+    assert config == expected