config: apply --override-ini eagerly

Currently ini overrides are handled lazily in `getini`, but I think it
just complicates things and I don't see a reason to it lazily.

Do it eagerly in `determine_setup` instead.

Author: bluetech

src/_pytest/config/__init__.py

@@ -1083,7 +1083,6 @@ def __init__(
         self.trace = self.pluginmanager.trace.root.get("config")
         self.hook: pluggy.HookRelay = PathAwareHookProxy(self.pluginmanager.hook)  # type: ignore[assignment]
         self._inicache: dict[str, Any] = {}
-        self._override_ini: Sequence[str] = ()
         self._opt2dest: dict[str, str] = {}
         self._cleanup_stack = contextlib.ExitStack()
         self.pluginmanager.register(self, "pytestconfig")
@@ -1251,6 +1250,7 @@ def _initini(self, args: Sequence[str]) -> None:
         )
         rootpath, inipath, inicfg, ignored_config_files = determine_setup(
             inifile=ns.inifilename,
+            override_ini=ns.override_ini,
             args=ns.file_or_dir + unknown_args,
             rootdir_cmd_arg=ns.rootdir or None,
             invocation_dir=self.invocation_params.dir,
@@ -1272,7 +1272,6 @@ def _initini(self, args: Sequence[str]) -> None:
             type="args",
             default=[],
         )
-        self._override_ini = ns.override_ini or ()
 
     def _consider_importhook(self, args: Sequence[str]) -> None:
         """Install the PEP 302 import hook if using assertion rewriting.
@@ -1641,14 +1640,10 @@ def _getini(self, name: str):
             _description, type, default = self._parser._inidict[name]
         except KeyError as e:
             raise ValueError(f"unknown configuration value: {name!r}") from e
-        override_value = self._get_override_ini_value(name)
-        if override_value is None:
-            try:
-                value = self.inicfg[name]
-            except KeyError:
-                return default
-        else:
-            value = override_value
+        try:
+            value = self.inicfg[name]
+        except KeyError:
+            return default
         # Coerce the values based on types.
         #
         # Note: some coercions are only required if we are reading from .ini files, because
@@ -1719,23 +1714,6 @@ def _getconftest_pathlist(
             values.append(relroot)
         return values
 
-    def _get_override_ini_value(self, name: str) -> str | None:
-        value = None
-        # override_ini is a list of "ini=value" options.
-        # Always use the last item if multiple values are set for same ini-name,
-        # e.g. -o foo=bar1 -o foo=bar2 will set foo to bar2.
-        for ini_config in self._override_ini:
-            try:
-                key, user_ini_value = ini_config.split("=", 1)
-            except ValueError as e:
-                raise UsageError(
-                    f"-o/--override-ini expects option=value style (got: {ini_config!r})."
-                ) from e
-            else:
-                if key == name:
-                    value = user_ini_value
-        return value
-
     def getoption(self, name: str, default: Any = notset, skip: bool = False):
         """Return command line option value.
 

src/_pytest/config/findpaths.py

@@ -181,12 +181,35 @@ def get_dir_from_path(path: Path) -> Path:
     return [get_dir_from_path(path) for path in possible_paths if safe_exists(path)]
 
 
+def parse_override_ini(override_ini: Sequence[str] | None) -> dict[str, str]:
+    """Parse the -o/--override-ini command line arguments and return the overrides.
+
+    :raises UsageError:
+        If one of the values is malformed.
+    """
+    overrides = {}
+    # override_ini is a list of "ini=value" options.
+    # Always use the last item if multiple values are set for same ini-name,
+    # e.g. -o foo=bar1 -o foo=bar2 will set foo to bar2.
+    for ini_config in override_ini or ():
+        try:
+            key, user_ini_value = ini_config.split("=", 1)
+        except ValueError as e:
+            raise UsageError(
+                f"-o/--override-ini expects option=value style (got: {ini_config!r})."
+            ) from e
+        else:
+            overrides[key] = user_ini_value
+    return overrides
+
+
 CFG_PYTEST_SECTION = "[pytest] section in {filename} files is no longer supported, change to [tool:pytest] instead."
 
 
 def determine_setup(
     *,
     inifile: str | None,
+    override_ini: Sequence[str] | None,
     args: Sequence[str],
     rootdir_cmd_arg: str | None,
     invocation_dir: Path,
@@ -196,12 +219,16 @@ def determine_setup(
 
     :param inifile:
         The `--inifile` command line argument, if given.
+    :param override_ini:
+        The -o/--override-ini command line arguments, if given.
     :param args:
         The free command line arguments.
     :param rootdir_cmd_arg:
         The `--rootdir` command line argument, if given.
     :param invocation_dir:
         The working directory when pytest was invoked.
+
+    :raises UsageError:
     """
     rootdir = None
     dirs = get_dirs_from_args(args)
@@ -238,8 +265,12 @@ def determine_setup(
             raise UsageError(
                 f"Directory '{rootdir}' not found. Check your '--rootdir' option."
             )
+
+    ini_overrides = parse_override_ini(override_ini)
+    inicfg.update(ini_overrides)
+
     assert rootdir is not None
-    return rootdir, inipath, inicfg or {}, ignored_config_files
+    return rootdir, inipath, inicfg, ignored_config_files
 
 
 def is_fs_root(p: Path) -> bool:

testing/test_config.py

@@ -1631,6 +1631,7 @@ def test_with_ini(self, tmp_path: Path, name: str, contents: str) -> None:
         for args in ([str(tmp_path)], [str(a)], [str(b)]):
             rootpath, parsed_inipath, *_ = determine_setup(
                 inifile=None,
+                override_ini=None,
                 args=args,
                 rootdir_cmd_arg=None,
                 invocation_dir=Path.cwd(),
@@ -1639,6 +1640,7 @@ def test_with_ini(self, tmp_path: Path, name: str, contents: str) -> None:
             assert parsed_inipath == inipath
         rootpath, parsed_inipath, ini_config, _ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=[str(b), str(a)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1656,6 +1658,7 @@ def test_pytestini_overrides_empty_other(self, tmp_path: Path, name: str) -> Non
         (a / name).touch()
         rootpath, parsed_inipath, *_ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=[str(a)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1670,6 +1673,7 @@ def test_setuppy_fallback(self, tmp_path: Path) -> None:
         (tmp_path / "setup.py").touch()
         rootpath, inipath, inicfg, _ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=[str(a)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1682,6 +1686,7 @@ def test_nothing(self, tmp_path: Path, monkeypatch: MonkeyPatch) -> None:
         monkeypatch.chdir(tmp_path)
         rootpath, inipath, inicfg, _ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=[str(tmp_path)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1709,6 +1714,7 @@ def test_with_specific_inifile(
         p.write_text(contents, encoding="utf-8")
         rootpath, inipath, ini_config, _ = determine_setup(
             inifile=str(p),
+            override_ini=None,
             args=[str(tmp_path)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1728,6 +1734,7 @@ def test_explicit_config_file_sets_rootdir(
         # No config file is explicitly given: rootdir is determined to be cwd.
         rootpath, found_inipath, *_ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=[str(tests_dir)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1740,6 +1747,7 @@ def test_explicit_config_file_sets_rootdir(
         inipath.touch()
         rootpath, found_inipath, *_ = determine_setup(
             inifile=str(inipath),
+            override_ini=None,
             args=[str(tests_dir)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1757,6 +1765,7 @@ def test_with_arg_outside_cwd_without_inifile(
         b.mkdir()
         rootpath, inifile, *_ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=[str(a), str(b)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1773,6 +1782,7 @@ def test_with_arg_outside_cwd_with_inifile(self, tmp_path: Path) -> None:
         inipath.touch()
         rootpath, parsed_inipath, *_ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=[str(a), str(b)],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1787,6 +1797,7 @@ def test_with_non_dir_arg(
         monkeypatch.chdir(tmp_path)
         rootpath, inipath, *_ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=dirs,
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1803,6 +1814,7 @@ def test_with_existing_file_in_subdir(
         monkeypatch.chdir(tmp_path)
         rootpath, inipath, *_ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=["a/exist"],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1822,6 +1834,7 @@ def test_with_config_also_in_parent_directory(
 
         rootpath, inipath, *_ = determine_setup(
             inifile=None,
+            override_ini=None,
             args=["tests/"],
             rootdir_cmd_arg=None,
             invocation_dir=Path.cwd(),
@@ -1978,7 +1991,7 @@ def test_addopts_before_initini(
         monkeypatch.setenv("PYTEST_ADDOPTS", f"-o cache_dir={cache_dir}")
         config = _config_for_test
         config._preparse([], addopts=True)
-        assert config._override_ini == [f"cache_dir={cache_dir}"]
+        assert config.inicfg.get("cache_dir") == cache_dir
 
     def test_addopts_from_env_not_concatenated(
         self, monkeypatch: MonkeyPatch, _config_for_test
@@ -2016,7 +2029,7 @@ def test_override_ini_does_not_contain_paths(
         """Check that -o no longer swallows all options after it (#3103)"""
         config = _config_for_test
         config._preparse(["-o", "cache_dir=/cache", "/some/test/path"])
-        assert config._override_ini == ["cache_dir=/cache"]
+        assert config.inicfg.get("cache_dir") == "/cache"
 
     def test_multiple_override_ini_options(self, pytester: Pytester) -> None:
         """Ensure a file path following a '-o' option does not generate an error (#3103)"""