Fix faulty enum check during helptext generation

dcargs/_arguments.py

@@ -416,7 +416,7 @@ def transform_generate_helptext(arg: ArgumentDefinition) -> ArgumentDefinition:
             if arg.action is not None:
                 # Don't show defaults for boolean flags.
                 assert arg.action in ("store_true", "store_false")
-            elif arg.default is not None and hasattr(arg.default, "name"):
+            elif arg.default is not None and isinstance(arg.default, enum.Enum):
                 # Special case for enums.
                 help_parts.append(f"(default: {arg.default.name})")
             elif not arg.required:

setup.py

@@ -5,7 +5,7 @@
 
 setup(
     name="dcargs",
-    version="0.0.16",
+    version="0.0.17",
     description="Portable, reusable, strongly typed CLIs from dataclass definitions",
     long_description=long_description,
     long_description_content_type="text/markdown",

tests/test_docstrings.py → tests/test_helptext.py

@@ -1,6 +1,8 @@
 import contextlib
 import dataclasses
+import enum
 import io
+import pathlib
 from typing import Generic, List, Optional, Tuple, TypeVar
 
 import pytest
@@ -30,6 +32,26 @@ class Helptext:
     assert "--z INT     Documentation 3 (default: 3)\n" in helptext
 
 
+def test_helptext_defaults():
+    class Color(enum.Enum):
+        RED = enum.auto()
+        GREEN = enum.auto()
+        BLUE = enum.auto()
+
+    @dataclasses.dataclass
+    class HelptextWithVariousDefaults:
+        x: pathlib.Path = pathlib.Path("/some/path/to/a/file")
+        y: Color = Color.RED
+
+    f = io.StringIO()
+    with pytest.raises(SystemExit):
+        with contextlib.redirect_stdout(f):
+            dcargs.parse(HelptextWithVariousDefaults, args=["--help"])
+    helptext = f.getvalue()
+    assert "--x PATH              (default: /some/path/to/a/file)\n" in helptext
+    assert "--y {RED,GREEN,BLUE}  (default: RED)\n" in helptext
+
+
 def test_multiline_helptext():
     @dataclasses.dataclass
     class HelptextMultiline: