config: fallback confcutdir to rootpath if inipath is not set

changelog/11043.improvement.rst

@@ -0,0 +1,3 @@
+When `--confcutdir` is not specified, and there is no config file present, the conftest cutoff directory (`--confcutdir`) is now set to the :ref:`rootdir`.
+Previously in such cases, `conftest.py` files would be probed all the way to the root directory of the filesystem.
+If you are badly affected by this change, consider adding an empty config file to your desired cutoff directory, or explicitly set `--confcutdir`.

src/_pytest/config/__init__.py

@@ -1261,8 +1261,11 @@ def _preparse(self, args: List[str], addopts: bool = True) -> None:
                 _pytest.deprecated.STRICT_OPTION, stacklevel=2
             )
 
-        if self.known_args_namespace.confcutdir is None and self.inipath is not None:
-            confcutdir = str(self.inipath.parent)
+        if self.known_args_namespace.confcutdir is None:
+            if self.inipath is not None:
+                confcutdir = str(self.inipath.parent)
+            else:
+                confcutdir = str(self.rootpath)
             self.known_args_namespace.confcutdir = confcutdir
         try:
             self.hook.pytest_load_initial_conftests(

testing/test_config.py

@@ -179,6 +179,23 @@ def test_toml_parse_error(self, pytester: Pytester) -> None:
         assert result.ret != 0
         result.stderr.fnmatch_lines("ERROR: *pyproject.toml: Invalid statement*")
 
+    def test_confcutdir_default_without_configfile(self, pytester: Pytester) -> None:
+        # If --confcutdir is not specified, and there is no configfile, default
+        # to the roothpath.
+        sub = pytester.mkdir("sub")
+        os.chdir(sub)
+        config = pytester.parseconfigure()
+        assert config.pluginmanager._confcutdir == sub
+
+    def test_confcutdir_default_with_configfile(self, pytester: Pytester) -> None:
+        # If --confcutdir is not specified, and there is a configfile, default
+        # to the configfile's directory.
+        pytester.makeini("[pytest]")
+        sub = pytester.mkdir("sub")
+        os.chdir(sub)
+        config = pytester.parseconfigure()
+        assert config.pluginmanager._confcutdir == pytester.path
+
     @pytest.mark.xfail(reason="probably not needed")
     def test_confcutdir(self, pytester: Pytester) -> None:
         sub = pytester.mkdir("sub")

testing/test_conftest.py

@@ -594,7 +594,13 @@ def test_parsefactories_relative_node_ids(
         print("pytestarg        : %s" % testarg)
         print("expected pass    : %s" % expect_ntests_passed)
         os.chdir(dirs[chdir])
-        reprec = pytester.inline_run(testarg, "-q", "--traceconfig")
+        reprec = pytester.inline_run(
+            testarg,
+            "-q",
+            "--traceconfig",
+            "--confcutdir",
+            pytester.path,
+        )
         reprec.assertoutcome(passed=expect_ntests_passed)