Correctly check literal values in configuration. (#205)

src/heisskleber/core/config.py

@@ -3,7 +3,7 @@
 import logging
 from dataclasses import dataclass, fields
 from pathlib import Path
-from typing import Any, TextIO, TypeVar, Union
+from typing import Any, Literal, TextIO, TypeVar, Union, get_args, get_origin
 
 import yaml  # type: ignore[import-untyped]
 
@@ -48,6 +48,16 @@ def _parser(path: Path) -> dict[str, Any]:
         raise ValueError
 
 
+def _check_type(value: Any, expected_type: Any) -> bool:
+    origin = get_origin(expected_type)
+    if origin is Literal:  # Explicitly check literal
+        if value not in get_args(expected_type):
+            logger.exception("%s is not part of %s", value, get_args(expected_type))
+            raise TypeError
+        return True
+    return isinstance(value, expected_type)
+
+
 @dataclass
 class BaseConf:
     """Default configuration class for generic configuration info."""
@@ -58,13 +68,11 @@ class BaseConf:
             value = getattr(self, field.name)
             if value is None:  # Allow optional fields
                 continue
-            if not isinstance(value, field.type):  # Failed field comparison
-                raise TypeError
-            if (  # Failed Union comparison
-                hasattr(field.type, "__origin__")
-                and field.type.__origin__ is Union
-                and not any(isinstance(value, t) for t in field.type.__args__)
-            ):
+            if hasattr(field.type, "__origin__") and field.type.__origin__ is Union:
+                if not any(_check_type(value, t) for t in field.type.__args__):
+                    raise TypeError
+                continue
+            if not _check_type(value, field.type):  # Failed field comparison
                 raise TypeError
 
     @classmethod

tests/core/test_config.py

@@ -1,8 +1,11 @@
+import logging
 from dataclasses import dataclass
+from typing import Literal
 
 import pytest
 
 from heisskleber.core import BaseConf
+from heisskleber.core.config import _check_type
 
 
 @dataclass
@@ -53,3 +56,29 @@ def test_conf_from_file() -> None:
     assert test_conf.name == "Frodo"
     assert test_conf.age == 30
     assert test_conf.speed == 0.5
+
+
+@dataclass
+class ConfigWithLiteral(BaseConf):
+    direction: Literal["U", "D"] = "U"
+
+
+def test_parses_literal() -> None:
+    test_dict = {"direction": "U"}
+    expected = ConfigWithLiteral(direction="U")
+
+    config = ConfigWithLiteral.from_dict(test_dict)
+
+    assert config == expected
+
+
+def test_logs_literal_error(caplog: pytest.LogCaptureFixture) -> None:
+    caplog.set_level(logging.ERROR)
+
+    expected = Literal[1, 2, 3]
+
+    with pytest.raises(TypeError):
+        _check_type(4, expected)
+
+    assert len(caplog.records) == 1
+    assert "4 is not part of (1, 2, 3)" in caplog.text

tests/serial/test_serial_config.py

@@ -0,0 +1,9 @@
+from heisskleber.serial import SerialConf
+
+
+def test_serial_config() -> None:
+    config_dict = {"port": "/test/serial", "baudrate": 5000, "parity": "N", "stopbits": 1}
+
+    config = SerialConf.from_dict(config_dict)
+
+    assert config == SerialConf(port="/test/serial", baudrate=5000, parity="N", stopbits=1)