fix comment

src/_pytest/main.py

@@ -12,6 +12,7 @@
 from pathlib import Path
 import sys
 from typing import AbstractSet
+from typing import Any
 from typing import Callable
 from typing import Dict
 from typing import final
@@ -365,6 +366,20 @@ def pytest_runtestloop(session: Session) -> bool:
     return True
 
 
+def _decode_toml_file(toml: Path) -> dict[str, Any] | None:
+    """Attempt to decode a toml file into a dict, returning None if fails."""
+    if sys.version_info >= (3, 11):
+        import tomllib
+    else:
+        import tomli as tomllib
+
+    try:
+        toml_text = toml.read_text(encoding="utf-8")
+        return tomllib.loads(toml_text)
+    except tomllib.TOMLDecodeError:
+        return None
+
+
 def _in_build(path: Path) -> bool:
     """Attempt to detect if ``path`` is the root of a buildsystem's artifacts
     by checking known dirnames patterns, and the presence of configuration in
@@ -374,9 +389,21 @@ def _in_build(path: Path) -> bool:
         return False
 
     if any(fnmatch_ex(pat, path) for pat in ("build", "dist")):
-        indicators = ("setup.py", "setup.cfg", "pyproject.toml")
-        if any((path.parent / f).is_file() for f in indicators):
-            return True
+        setup_cfg = path.parent / "setup.cfg"
+        if (setup_cfg).is_file():
+            setup_py = path.parent / "setup.py"
+            if setup_py.is_file():
+                return True
+
+            pyproject_toml = path.parent / "pyproject.toml"
+            if pyproject_toml.is_file():
+                config = _decode_toml_file(pyproject_toml)
+                if config:
+                    if any(
+                        "setuptools" in cfg
+                        for cfg in config.get("build-system", {}).get("requires", {})
+                    ):
+                        return True
 
     return False
 

testing/test_collection.py

@@ -275,14 +275,10 @@ def test_missing_permissions_on_unselected_directory_doesnt_crash(
         result.assert_outcomes(passed=1)
 
     known_build_dirs = pytest.mark.parametrize("build_dir", ["build", "dist"])
-    known_buildsystem_env = pytest.mark.parametrize(
-        "buildsystem_indicator_file", ["setup.py", "setup.cfg", "pyproject.toml"]
-    )
 
     @known_build_dirs
-    @known_buildsystem_env
-    def test_build_dirs_collected(
-        self, pytester: Pytester, build_dir: str, buildsystem_indicator_file: str
+    def test_build_dirs_collected_when_setuptools_setup_py_present(
+        self, pytester: Pytester, build_dir: str
     ) -> None:
         tmp_path = pytester.path
         ensure_file(tmp_path / build_dir / "test_module.py").write_text(
@@ -292,13 +288,17 @@ def test_build_dirs_collected(
         result = pytester.runpytest("--collect-only").stdout.str()
         assert "test_module" in result
 
-        ensure_file(tmp_path / buildsystem_indicator_file)
+        ensure_file(tmp_path / "setup.cfg")
+
+        result = pytester.runpytest("--collect-only").stdout.str()
+        assert "test_module" in result
 
+        ensure_file(tmp_path / "setup.py")
         result = pytester.runpytest("--collect-only").stdout.str()
         assert "test_module" not in result
 
     @known_build_dirs
-    def test_build_dirs_collected_when_setuptools_configuration_present(
+    def test_build_dirs_collected_when_setuptools_present_in_pyproject_toml(
         self, pytester: Pytester, build_dir: str
     ) -> None:
         tmp_path = pytester.path
@@ -314,7 +314,11 @@ def test_build_dirs_collected_when_setuptools_configuration_present(
         result = pytester.runpytest("--collect-only").stdout.str()
         assert "test_module" in result
 
-        ensure_file(tmp_path / "setup.py")
+        ensure_file(tmp_path / "pyproject.toml").write_text(
+            '[build-system]\nrequires = ["setuptools", "setuptools-scm"]\n',
+            encoding="utf-8",
+        )
+        result = pytester.runpytest("--collect-only").stdout.str()
         assert "test_module" not in result