Consider testpaths for initial conftests

The 'testpaths' option is meant to be identical to execute
pytest passing the 'testpaths' directories explicitly.

Fix #10987

changelog/10987.bugfix.rst

@@ -0,0 +1 @@
+:confval:`testpaths` is now honored to load root ``conftests``.

doc/en/reference/reference.rst

@@ -1713,13 +1713,12 @@ passed multiple times. The expected format is ``name=value``. For example::
 
 .. confval:: testpaths
 
-
-
    Sets list of directories that should be searched for tests when
    no specific directories, files or test ids are given in the command line when
    executing pytest from the :ref:`rootdir <rootdir>` directory.
    File system paths may use shell-style wildcards, including the recursive
    ``**`` pattern.
+
    Useful when all project tests are in a known location to speed up
    test collection and to avoid picking up undesired tests by accident.
 
@@ -1728,8 +1727,17 @@ passed multiple times. The expected format is ``name=value``. For example::
         [pytest]
         testpaths = testing doc
 
-   This tells pytest to only look for tests in ``testing`` and ``doc``
-   directories when executing from the root directory.
+   This configuration means that executing:
+
+   .. code-block:: console
+
+       pytest
+
+   has the same practical effects as executing:
+
+   .. code-block:: console
+
+       pytest testing doc
 
 
 .. confval:: tmp_path_retention_count

src/_pytest/config/__init__.py

@@ -526,7 +526,10 @@ def pytest_configure(self, config: "Config") -> None:
     # Internal API for local conftest plugin handling.
     #
     def _set_initial_conftests(
-        self, namespace: argparse.Namespace, rootpath: Path
+        self,
+        namespace: argparse.Namespace,
+        rootpath: Path,
+        testpaths_ini: Sequence[str],
     ) -> None:
         """Load initial conftest files given a preparsed "namespace".
 
@@ -543,7 +546,7 @@ def _set_initial_conftests(
         )
         self._noconftest = namespace.noconftest
         self._using_pyargs = namespace.pyargs
-        testpaths = namespace.file_or_dir
+        testpaths = namespace.file_or_dir + testpaths_ini
         foundanchor = False
         for testpath in testpaths:
             path = str(testpath)
@@ -552,7 +555,20 @@ def _set_initial_conftests(
             if i != -1:
                 path = path[:i]
             anchor = absolutepath(current / path)
-            if anchor.exists():  # we found some file object
+
+            # On Python 3.7 on Windows, anchor.exists() might raise
+            # if the anchor contains glob characters (for example "*//tests"), specially
+            # in the case of the 'testpaths' ini option.
+            # Using an explicit version check to remove this code later once
+            # Python 3.7 is dropped.
+            if sys.version_info[:2] == (3, 7):
+                try:
+                    anchor_exists = anchor.exists()
+                except OSError:  # pragma: no cover
+                    anchor_exists = False
+            else:
+                anchor_exists = anchor.exists()
+            if anchor_exists:  # We found some file object.
                 self._try_load_conftest(anchor, namespace.importmode, rootpath)
                 foundanchor = True
         if not foundanchor:
@@ -1131,7 +1147,9 @@ def _processopt(self, opt: "Argument") -> None:
     @hookimpl(trylast=True)
     def pytest_load_initial_conftests(self, early_config: "Config") -> None:
         self.pluginmanager._set_initial_conftests(
-            early_config.known_args_namespace, rootpath=early_config.rootpath
+            early_config.known_args_namespace,
+            rootpath=early_config.rootpath,
+            testpaths_ini=self.getini("testpaths"),
         )
 
     def _initini(self, args: Sequence[str]) -> None:

testing/test_collection.py

@@ -1247,6 +1247,29 @@ def test_collect_pyargs_with_testpaths(
     result.stdout.fnmatch_lines(["*1 passed in*"])
 
 
+def test_initial_conftests_with_testpaths(pytester: Pytester) -> None:
+    """The testpaths ini option should load conftests in those paths as 'initial' (#10987)."""
+    p = pytester.mkdir("some_path")
+    p.joinpath("conftest.py").write_text(
+        textwrap.dedent(
+            """
+            def pytest_sessionstart(session):
+                raise Exception("pytest_sessionstart hook is successfully run")
+            """
+        )
+    )
+    pytester.makeini(
+        """
+        [pytest]
+        testpaths = some_path
+        """
+    )
+    result = pytester.runpytest()
+    result.stdout.fnmatch_lines(
+        "INTERNALERROR* Exception: pytest_sessionstart hook is successfully run"
+    )
+
+
 def test_collect_symlink_file_arg(pytester: Pytester) -> None:
     """Collect a direct symlink works even if it does not match python_files (#4325)."""
     real = pytester.makepyfile(

testing/test_conftest.py

@@ -35,7 +35,7 @@ def __init__(self) -> None:
             self.importmode = "prepend"
 
     namespace = cast(argparse.Namespace, Namespace())
-    conftest._set_initial_conftests(namespace, rootpath=Path(args[0]))
+    conftest._set_initial_conftests(namespace, rootpath=Path(args[0]), testpaths_ini=[])
 
 
 @pytest.mark.usefixtures("_sys_snapshot")