Allow task functions to be partialed. (#536)

docs/source/changes.md

@@ -22,6 +22,7 @@ releases are available on [PyPI](https://pypi.org/project/pytask) and
 - {pull}`525` enables pytask to work with remote files using universal_pathlib.
 - {pull}`528` improves the codecov setup and coverage.
 - {pull}`535` reenables and fixes tests with Jupyter.
+- {pull}`536` allows partialed functions to be task functions.
 
 ## 0.4.4 - 2023-12-04
 

src/_pytask/task_utils.py

@@ -1,6 +1,7 @@
 """Contains utilities related to the ``@pytask.mark.task`` decorator."""
 from __future__ import annotations
 
+import functools
 import inspect
 from collections import defaultdict
 from types import BuiltinFunctionType
@@ -115,7 +116,7 @@ def wrapper(func: Callable[..., Any]) -> Callable[..., Any]:
         path = get_file(unwrapped)
 
         parsed_kwargs = {} if kwargs is None else kwargs
-        parsed_name = name if isinstance(name, str) else func.__name__
+        parsed_name = _parse_name(unwrapped, name)
         parsed_after = _parse_after(after)
 
         if hasattr(unwrapped, "pytask_meta"):
@@ -148,6 +149,21 @@ def wrapper(func: Callable[..., Any]) -> Callable[..., Any]:
     return wrapper
 
 
+def _parse_name(func: Callable[..., Any], name: str | None) -> str:
+    """Parse name from task function."""
+    if name:
+        return name
+
+    if isinstance(func, functools.partial):
+        func = func.func
+
+    if hasattr(func, "__name__"):
+        return func.__name__
+
+    msg = "Cannot infer name for task function."
+    raise NotImplementedError(msg)
+
+
 def _parse_after(
     after: str | Callable[..., Any] | list[Callable[..., Any]] | None,
 ) -> str | list[Callable[..., Any]]:

tests/test_task.py

@@ -349,8 +349,9 @@ def func(content):
 
     result = runner.invoke(cli, [tmp_path.as_posix()])
 
-    assert result.exit_code == ExitCode.COLLECTION_FAILED
-    assert "1  Collected errors and tasks" in result.output
+    assert result.exit_code == ExitCode.OK
+    assert "1  Succeeded" in result.output
+    assert tmp_path.joinpath("out.txt").read_text() == "hello"
 
 
 @pytest.mark.end_to_end()

tests/test_task_utils.py

@@ -1,10 +1,12 @@
 from __future__ import annotations
 
 from contextlib import ExitStack as does_not_raise  # noqa: N813
+from functools import partial
 from typing import NamedTuple
 
 import pytest
 from _pytask.task_utils import _arg_value_to_id_component
+from _pytask.task_utils import _parse_name
 from _pytask.task_utils import _parse_task_kwargs
 from attrs import define
 
@@ -56,3 +58,26 @@ def test_parse_task_kwargs(kwargs, expectation, expected):
     with expectation:
         result = _parse_task_kwargs(kwargs)
         assert result == expected
+
+
+def task_func(x):  # noqa: ARG001  # pragma: no cover
+    pass
+
+
+@pytest.mark.unit()
+@pytest.mark.parametrize(
+    ("func", "name", "expectation", "expected"),
+    [
+        (task_func, None, does_not_raise(), "task_func"),
+        (task_func, "name", does_not_raise(), "name"),
+        (partial(task_func, x=1), None, does_not_raise(), "task_func"),
+        (partial(task_func, x=1), "name", does_not_raise(), "name"),
+        (lambda x: None, None, does_not_raise(), "<lambda>"),  # noqa: ARG005
+        (partial(lambda x: None, x=1), None, does_not_raise(), "<lambda>"),  # noqa: ARG005
+        (1, None, pytest.raises(NotImplementedError, match="Cannot"), None),
+    ],
+)
+def test_parse_name(func, name, expectation, expected):
+    with expectation:
+        result = _parse_name(func, name)
+        assert result == expected