Accept type expressions in Parser.addini(type=...)

changelog/14675.improvement.rst

@@ -0,0 +1 @@
+:func:`parser.addini <pytest.Parser.addini>` now also accepts plain Python types (``str``, ``bool``, ``int``, ``float``) and unions of them (for example ``int | str``) for its ``type`` argument, in addition to the existing string tags. A union accepts a value of any of its member types.

src/_pytest/config/__init__.py

@@ -35,6 +35,7 @@
 from typing import Final
 from typing import final
 from typing import IO
+from typing import Literal
 from typing import TextIO
 from typing import TYPE_CHECKING
 import warnings
@@ -1747,6 +1748,34 @@ def _getini(self, name: str):
         value = selected.value
         mode = selected.mode
 
+        if not isinstance(type, tuple):
+            return self._getini_value(mode, name, canonical_name, type, value, default)
+
+        # A tuple type means "accept any of these types"; try each in order and
+        # return the first that accepts the value.
+        for tag in type:
+            try:
+                return self._getini_value(
+                    mode, name, canonical_name, tag, value, default
+                )
+            except (TypeError, ValueError):
+                pass
+        value_type = builtins.type(value).__name__
+        raise TypeError(
+            f"{self.inipath}: config option '{name}' expects one of "
+            f"{' | '.join(type)}, got {value_type}: {value!r}"
+        )
+
+    def _getini_value(
+        self,
+        mode: Literal["ini", "toml"],
+        name: str,
+        canonical_name: str,
+        type: str,
+        value: object,
+        default: Any,
+    ):
+        """Convert a config value, read in the given mode, to the option's type."""
         if mode == "ini":
             # In ini mode, values are always str | list[str].
             assert isinstance(value, (str, list))

src/_pytest/config/argparsing.py

@@ -7,10 +7,15 @@
 import os
 import sys
 import textwrap
+import types
 from typing import Any
+from typing import cast
 from typing import final
+from typing import get_args
+from typing import get_origin
 from typing import Literal
 from typing import NoReturn
+from typing import Union
 
 from .exceptions import UsageError
 import _pytest._io
@@ -20,6 +25,44 @@
 
 FILE_OR_DIR = "file_or_dir"
 
+#: The string tags accepted by :meth:`Parser.addini` for its ``type`` argument.
+_IniTypeTag = Literal[
+    "string", "paths", "pathlist", "args", "linelist", "bool", "int", "float"
+]
+
+#: An ini option type, as stored internally after normalization: either a
+#: single tag, or a tuple of tags meaning "accept a value of any of these
+#: types" (e.g. ``("int", "string")``, normalized from ``int | str``).
+IniType = _IniTypeTag | tuple[_IniTypeTag, ...]
+
+_INI_TYPE_TAGS: tuple[str, ...] = get_args(_IniTypeTag)
+
+#: Maps the plain Python types accepted by :meth:`Parser.addini` for its
+#: ``type`` argument to the equivalent string tag.
+_INI_TYPE_TO_TAG: dict[type, _IniTypeTag] = {
+    str: "string",
+    bool: "bool",
+    int: "int",
+    float: "float",
+}
+
+
+def _ini_type_to_tag(name: str, type_: object) -> _IniTypeTag:
+    """Normalize one member of an `addini(type=...)` argument to a string tag.
+
+    Raise ValueError for anything that is neither a known tag nor a supported
+    plain Python type.
+    """
+    if isinstance(type_, str) and type_ in _INI_TYPE_TAGS:
+        return cast("_IniTypeTag", type_)
+    if isinstance(type_, type) and type_ in _INI_TYPE_TO_TAG:
+        return _INI_TYPE_TO_TAG[type_]
+    raise ValueError(
+        f"invalid type for ini option {name!r}: {type_!r} (expected one of "
+        f"{', '.join(repr(tag) for tag in _INI_TYPE_TAGS)}, one of the types "
+        "str, bool, int, float, or a union of these types such as `int | str`)"
+    )
+
 
 @final
 class Parser:
@@ -54,7 +97,7 @@ def __init__(
         file_or_dir_arg = self.optparser.add_argument(FILE_OR_DIR, nargs="*")
         file_or_dir_arg.completer = filescompleter  # type: ignore
 
-        self._inidict: dict[str, tuple[str, str, Any]] = {}
+        self._inidict: dict[str, tuple[str, IniType, Any]] = {}
         # Maps alias -> canonical name.
         self._ini_aliases: dict[str, str] = {}
 
@@ -182,9 +225,9 @@ def addini(
         self,
         name: str,
         help: str,
-        type: Literal[
-            "string", "paths", "pathlist", "args", "linelist", "bool", "int", "float"
-        ]
+        type: _IniTypeTag
+        | type[bool | int | float | str]
+        | types.UnionType
         | None = None,
         default: Any = NOTSET,
         *,
@@ -210,6 +253,18 @@ def addini(
 
                     The ``float`` and ``int`` types.
 
+            For the scalar types, the plain Python type may be passed instead
+            of the string tag: ``str``, ``bool``, ``int`` and ``float`` (for
+            example ``type=int``). A union of these types accepts a value of
+            any of its members, for example ``int | str``. In TOML
+            configuration files the value may then be any of the member types;
+            string-based formats (INI files, ``-o`` overrides) coerce it to the
+            first member that accepts it.
+
+            .. versionadded:: 9.1
+
+                Passing a type expression such as ``int`` or ``int | str``.
+
             For ``paths`` and ``pathlist`` types, they are considered relative to the config-file.
             In case the execution is happening without a config-file defined,
             they will be considered relative to the current working directory (for example with ``--override-ini``).
@@ -233,23 +288,26 @@ def addini(
         The value of configuration keys can be retrieved via a call to
         :py:func:`config.getini(name) <pytest.Config.getini>`.
         """
-        assert type in (
-            None,
-            "string",
-            "paths",
-            "pathlist",
-            "args",
-            "linelist",
-            "bool",
-            "int",
-            "float",
-        )
+        ini_type: IniType
         if type is None:
-            type = "string"
+            ini_type = "string"
+        elif get_origin(type) in (Union, types.UnionType):
+            ini_type = tuple(
+                _ini_type_to_tag(name, member) for member in get_args(type)
+            )
+        else:
+            ini_type = _ini_type_to_tag(name, type)
         if default is NOTSET:
-            default = get_ini_default_for_type(type)
+            if isinstance(ini_type, tuple):
+                # A union has no unambiguous implicit default; require an
+                # explicit one.
+                raise ValueError(
+                    f"ini option {name!r} has a union type, which has no "
+                    "implicit default; pass an explicit `default` to `addini`"
+                )
+            default = get_ini_default_for_type(ini_type)
 
-        self._inidict[name] = (help, type, default)
+        self._inidict[name] = (help, ini_type, default)
 
         for alias in aliases:
             if alias in self._inidict:
@@ -261,11 +319,7 @@ def addini(
             self._ini_aliases[alias] = name
 
 
-def get_ini_default_for_type(
-    type: Literal[
-        "string", "paths", "pathlist", "args", "linelist", "bool", "int", "float"
-    ],
-) -> Any:
+def get_ini_default_for_type(type: _IniTypeTag) -> Any:
     """
     Used by addini to get the default value for a given config option type, when
     default is not supplied.

src/_pytest/helpconfig.py

@@ -200,7 +200,8 @@ def showhelp(config: Config) -> None:
         help, type, _default = config._parser._inidict[name]
         if help is None:
             raise TypeError(f"help argument cannot be None for {name}")
-        spec = f"{name} ({type}):"
+        type_repr = " | ".join(type) if isinstance(type, tuple) else type
+        spec = f"{name} ({type_repr}):"
         tw.write(f"  {spec}")
         spec_len = len(spec)
         if spec_len > (indent_len - 3):

testing/test_config.py

@@ -1089,6 +1089,91 @@ def pytest_addoption(parser):
         ):
             _ = config.getini("ini_param")
 
+    @pytest.mark.parametrize(
+        "section, value, expected",
+        [
+            # Native TOML: int and str are both accepted; the first union
+            # member that matches wins (int before str).
+            ("[tool.pytest]", '"7"', "7"),
+            ("[tool.pytest]", "7", 7),
+            # ini_options mode stringifies, then coerces to the first member.
+            ("[tool.pytest.ini_options]", '"7"', 7),
+            ("[tool.pytest.ini_options]", "7", 7),
+        ],
+        ids=["native-str", "native-int", "ini-options-str", "ini-options-int"],
+    )
+    def test_addini_union_type(
+        self, pytester: Pytester, section: str, value: str, expected: object
+    ) -> None:
+        pytester.makeconftest(
+            """
+            def pytest_addoption(parser):
+                parser.addini("ini_param", "", type=int | str, default=None)
+        """
+        )
+        pytester.makepyprojecttoml(
+            f"""
+            {section}
+            ini_param = {value}
+            """
+        )
+        config = pytester.parseconfig()
+        result = config.getini("ini_param")
+        assert result == expected
+        assert type(result) is type(expected)
+
+    def test_addini_union_type_invalid_value(self, pytester: Pytester) -> None:
+        pytester.makeconftest(
+            """
+            def pytest_addoption(parser):
+                parser.addini("ini_param", "", type=int | str, default=None)
+        """
+        )
+        pytester.makepyprojecttoml(
+            """
+            [tool.pytest]
+            ini_param = [1, 2]
+            """
+        )
+        config = pytester.parseconfig()
+        with pytest.raises(
+            TypeError, match=r"config option 'ini_param' expects one of int \| string"
+        ):
+            _ = config.getini("ini_param")
+
+    def test_addini_plain_type(self, pytester: Pytester) -> None:
+        """A plain Python type is accepted as an alias of its string tag."""
+        pytester.makeconftest(
+            """
+            def pytest_addoption(parser):
+                parser.addini("ini_param", "", type=int)
+        """
+        )
+        pytester.makepyprojecttoml(
+            """
+            [tool.pytest]
+            ini_param = 7
+            """
+        )
+        config = pytester.parseconfig()
+        assert config.getini("ini_param") == 7
+
+    def test_addini_invalid_type(self, pytester: Pytester) -> None:
+        parser = Parser(_ispytest=True)
+        with pytest.raises(ValueError, match="invalid type for ini option 'ini_param'"):
+            parser.addini("ini_param", "", type="integer")  # type: ignore[arg-type]
+        with pytest.raises(ValueError, match="invalid type for ini option 'ini_param'"):
+            parser.addini("ini_param", "", type=dict)  # type: ignore[arg-type]
+        with pytest.raises(ValueError, match="invalid type for ini option 'ini_param'"):
+            parser.addini("ini_param", "", type=int | dict)
+
+    def test_addini_union_type_requires_default(self) -> None:
+        parser = Parser(_ispytest=True)
+        with pytest.raises(
+            ValueError, match="union type, which has no implicit default"
+        ):
+            parser.addini("ini_param", "", type=int | str)
+
     def test_addinivalue_line_existing(self, pytester: Pytester) -> None:
         pytester.makeconftest(
             """