Enforce DATADIR to be type pathlib.Path (#35)

.mypy.ini

@@ -1,3 +1,4 @@
 [mypy]
 disallow_untyped_defs = True
-show_error_codes = True
+show_error_codes = True
+plugins = pydantic.mypy

pydax/_config.py

@@ -17,18 +17,17 @@
 "Module for defining and modifying global configs"
 
 
-from dataclasses import dataclass
 import pathlib
 
-from . import _typing
+from pydantic.dataclasses import dataclass
 
 
 @dataclass(frozen=True)
 class Config:
     """Global read-only configurations for PyDAX.
     """
     # DATADIR is the default dir where datasets files are downloaded/loaded to/from.
-    DATADIR: _typing.PathLike = pathlib.Path.home() / '.pydax' / 'data'
+    DATADIR: pathlib.Path = pathlib.Path.home() / '.pydax' / 'data'
 
 
 def get_config() -> Config:
@@ -39,7 +38,7 @@ def get_config() -> Config:
     return global_config  # type: ignore [name-defined]
 
 
-def init(**kwargs: _typing.PathLike) -> None:
+def init(**kwargs: pathlib.Path) -> None:
     """
     (Re-)initialize the PyDAX library. This includes updating PyDAX global configs.
 

pydax/dataset.py

@@ -199,7 +199,7 @@ def load_dataset(name: str, *,
 
     schema = load_schemata().schemata['dataset_schema'].export_schema('datasets', name, version)
 
-    data_dir = pathlib.Path(get_config().DATADIR) / name / version  # TODO issue 646
+    data_dir = get_config().DATADIR / name / version
     dataset = Dataset(schema=schema, data_dir=data_dir, mode=Dataset.InitializationMode.LAZY)
     if download and not dataset.is_downloaded():
         dataset.download()

setup.py

@@ -34,6 +34,7 @@
     install_requires=[
         "packaging >= 20.4",
         "pandas >= 1.1.0",
+        "pydantic >= 1.7.2",
         "PyYAML >= 5.3.1",
         "requests >= 2.24.0"],
     classifiers=[

tests/test_config.py

@@ -15,6 +15,10 @@
 #
 
 import pathlib
+import re
+
+import pytest
+from pydantic import ValidationError
 
 from pydax import get_config, init
 from pydax.dataset import Dataset
@@ -25,12 +29,25 @@ def test_default_data_dir(wikitext103_schema):
 
     pydax_data_home = pathlib.Path.home() / '.pydax' / 'data'
     assert get_config().DATADIR == pydax_data_home
+    assert isinstance(get_config().DATADIR, pathlib.Path)
 
 
 def test_custom_data_dir(tmp_path, wikitext103_schema):
     "Test to make sure Dataset constructor uses new global data dir if one was supplied earlier to pydax.init."
 
     init(DATADIR=tmp_path)
     assert get_config().DATADIR == tmp_path
+    assert isinstance(get_config().DATADIR, pathlib.Path)
     wikitext = Dataset(wikitext103_schema, data_dir=tmp_path, mode=Dataset.InitializationMode.LAZY)
     assert wikitext._data_dir == tmp_path
+    assert isinstance(wikitext._data_dir, pathlib.Path)
+
+
+def test_non_path_data_dir():
+    "Test exception when a nonpath is passed as DATADIR."
+
+    with pytest.raises(ValidationError) as e:
+        init(DATADIR=10)
+
+    assert re.search(r"1 validation error for Config\s+DATADIR\s+value is not a valid path \(type=type_error.path\)",
+                     str(e.value))