Do not perform interpolation for INI files

docs/changelog/2350.bugfix.rst

@@ -0,0 +1 @@
+Do not interpolate values when parsing ``tox.ini`` configuration files - by :user:`gaborbernat`.

src/tox/config/cli/ini.py

@@ -34,7 +34,7 @@ def __init__(self) -> None:
             self.config_file = self.config_file.absolute()
             try:
 
-                parser = ConfigParser()
+                parser = ConfigParser(interpolation=None)
                 with self.config_file.open() as file_handler:
                     parser.read_file(file_handler)
                 self.has_tox_section = parser.has_section(CORE.key)

src/tox/config/source/ini.py

@@ -24,7 +24,7 @@ class IniSource(Source, ABC):
 
     def __init__(self, path: Path, content: str | None = None) -> None:
         super().__init__(path)
-        self._parser = ConfigParser()
+        self._parser = ConfigParser(interpolation=None)
         if content is None:
             if not path.exists():
                 raise ValueError

tests/config/cli/test_cli_ini.py

@@ -9,6 +9,7 @@
 import pytest
 from pytest_mock import MockerFixture
 
+from tox.config.cli.ini import IniConfig
 from tox.config.cli.parse import get_options
 from tox.config.loader.api import Override
 from tox.pytest import CaptureFixture, LogCaptureFixture, MonkeyPatch
@@ -190,3 +191,11 @@ def test_bad_option_cli_ini(
         ),
     ]
     assert vars(parsed) == default_options
+
+
+def test_cli_ini_with_interpolated(tmp_path: Path, monkeypatch: MonkeyPatch) -> None:
+    to = tmp_path / "tox.ini"
+    to.write_text("[tox]\na = %(b)s")
+    monkeypatch.setenv("TOX_CONFIG_FILE", str(to))
+    conf = IniConfig()
+    assert conf.get("a", str)

tests/config/loader/ini/conftest.py

@@ -12,7 +12,7 @@ def mk_ini_conf(tmp_path: Path) -> Callable[[str], ConfigParser]:
     def _func(raw: str) -> ConfigParser:
         filename = tmp_path / "demo.ini"
         filename.write_bytes(raw.encode("utf-8"))  # win32: avoid CR normalization - what you pass is what you get
-        parser = ConfigParser()
+        parser = ConfigParser(interpolation=None)
         with filename.open() as file_handler:
             parser.read_file(file_handler)
         return parser

tests/config/source/test_source_ini.py

@@ -0,0 +1,10 @@
+from pathlib import Path
+
+from tox.config.loader.section import Section
+from tox.config.source.ini import IniSource
+
+
+def test_source_ini_with_interpolated(tmp_path: Path) -> None:
+    loader = IniSource(tmp_path, content="[tox]\na = %(c)s").get_loader(Section(None, "tox"), {})
+    assert loader is not None
+    loader.load_raw("a", None, None)

tests/session/cmd/test_show_config.py

@@ -24,7 +24,7 @@ def test_show_config_default_run_env(tox_project: ToxProjectCreator, monkeypatch
     outcome = list(state.envs.iter(only_active=False))
     assert outcome == [name]
     monkeypatch.delenv("TERM", raising=False)  # disable conditionally set flag
-    parser = ConfigParser()
+    parser = ConfigParser(interpolation=None)
     parser.read_string(result.out)
     assert list(parser.sections()) == [f"testenv:{name}", "tox"]
 
@@ -122,7 +122,7 @@ def test_show_config_pkg_env_once(
     )
     result = project.run("c")
     result.assert_success()
-    parser = ConfigParser()
+    parser = ConfigParser(interpolation=None)
     parser.read_string(result.out)
     sections = set(parser.sections())
     assert sections == {"testenv:.pkg", f"testenv:.pkg-{impl}{prev_ver}", f"testenv:py{prev_ver}", "testenv:py", "tox"}
@@ -138,7 +138,7 @@ def test_show_config_pkg_env_skip(
     )
     result = project.run("c")
     result.assert_success()
-    parser = ConfigParser()
+    parser = ConfigParser(interpolation=None)
     parser.read_string(result.out)
     sections = set(parser.sections())
     assert sections == {"testenv:.pkg", "tox", "testenv:py", f"testenv:py{prev_ver}"}
@@ -148,7 +148,7 @@ def test_show_config_select_only(tox_project: ToxProjectCreator) -> None:
     project = tox_project({"tox.ini": "[tox]\nenv_list=\n a\n b", "pyproject.toml": ""})
     result = project.run("c", "-e", ".pkg,b,.pkg")
     result.assert_success()
-    parser = ConfigParser()
+    parser = ConfigParser(interpolation=None)
     parser.read_string(result.out)
     sections = list(parser.sections())
     assert sections == ["testenv:.pkg", "testenv:b"]