feat pytest: partially enable behavior of CONFTEST_LOAD_POLICY_LOCAL for all tests

1. `module_node.path` (py3) or `fspath` (py2) are now always in the form `yatest.common.source_path("path/from/repo/root/to/my_test.py")` instead of the previous `partial.path.to.my_test.py`
2. `module_node.nodeid` is now always in the form `path/from/repo/root/to/my_test.py` instead of the previous `partial.path.to.my_test.py`
3. `module_node.name` was also changed to `path/from/repo/root/to/my_test.py`. But it is not recommended to specialize on that, it may change again shortly in the future
4. Refactorings, simplifications and unifications in `library/python/pytest`
commit_hash:8a5b4951208a034f94231b2f799eb0c32a6d787d

2 files changed, 61 insertions, 60 deletions

diff --git a/library/python/pytest/plugins/collection.py b/library/python/pytest/plugins/collection.py
index 039031635c6..e00d9292921 100644
--- a/library/python/pytest/plugins/collection.py
+++ b/library/python/pytest/plugins/collection.py
@@ -15,6 +15,7 @@ if six.PY3:
 
 from library.python.pytest import module_utils
 import library.python.testing.filter.filter as test_filter
+import yatest.common
 
 
 def _make_module_with_single_skipped_test(module_name, file_name, exc):
@@ -40,36 +41,30 @@ class LoadedModule(pytest.Module):
         self.module_name = name
         if namespace:
             assert name.startswith('__tests__.')
-            self.display_module_name = name[len('__tests__.'):]
+            self.display_module_name = name[len('__tests__.') :]
         else:
             self.display_module_name = name
         self.is_fake_module = False
         # Always passed to `super().__init__` explicitly.
         kwargs.pop('nodeid', None)
 
-        if os.getenv('CONFTEST_LOAD_POLICY') == 'LOCAL':
-            nodeid = module_utils.get_proper_module_path(self.module_name)
-            if nodeid is None:
-                self.is_fake_module = True
-                return
+        nodeid = module_utils.get_proper_module_path(self.module_name)
+        if nodeid is None:
+            self.is_fake_module = True
+            return
 
-            name = nodeid
-            if six.PY3:
-                kwargs['path'] = kwargs.get('path') or pathlib.Path(nodeid)
-            else:
-                raw_module_path = module_utils.get_module_file_path(self.module_name)
-                kwargs['fspath'] = kwargs.get('fspath') or py.path.local(raw_module_path)
-        else:
-            nodeid = self.display_module_name + '.py'
-            name = nodeid
-            if six.PY3:
-                kwargs['path'] = kwargs.get('path') or pathlib.Path(py.path.local())
-            else:
-                kwargs['fspath'] = kwargs.get('fspath') or py.path.local()
+        # Avoid specializing on `name`. It may change in the future if we add virtual collection nodes for directories.
+        name = nodeid
+        # `path` and `fspath` are required to be absolute paths.
+        # The original source or build directory may be unavailable (at least in CI) and is irrelevant at this point.
+        # Meanwhile, `source_path` is useful, because it allows to find nearby test data, like with vanilla pytest.
+        path = yatest.common.source_path(nodeid)
 
         if six.PY3:
+            kwargs['path'] = kwargs.get('path') or pathlib.Path(path)
             super().__init__(parent=parent, name=name, nodeid=nodeid, **kwargs)
         else:
+            kwargs['fspath'] = kwargs.get('fspath') or py.path.local(path)
             super(LoadedModule, self).__init__(parent=parent, nodeid=nodeid, **kwargs)
             self.name = name
 
@@ -83,7 +78,9 @@ class LoadedModule(pytest.Module):
             __import__(self.module_name)
         except pytest.skip.Exception as e:
             if not e.allow_module_level:
-                raise RuntimeError("Using pytest.skip outside of a test will skip the entire module. If that's your intention, pass `allow_module_level=True`.")
+                raise RuntimeError(
+                    "Using pytest.skip outside of a test will skip the entire module. If that's your intention, pass `allow_module_level=True`."
+                )
             # DEVTOOLSSUPPORT-79470: reraising pytest.skip.Exception from here seems to break reporting in ya plugin.
             # Instead, pretend to be a module with a single skipped test.
             return _make_module_with_single_skipped_test(self.module_name, self.nodeid, e)
@@ -114,10 +111,8 @@ class DoctestModule(LoadedModule):
             for test in finder.find(module, self.display_module_name):
                 if test.examples:  # skip empty doctests
                     yield getattr(_pytest.doctest.DoctestItem, 'from_parent', _pytest.doctest.DoctestItem)(
-                        name=test.name,
-                        parent=self,
-                        runner=runner,
-                        dtest=test)
+                        name=test.name, parent=self, runner=runner, dtest=test
+                    )
         except Exception:
             logging.exception('DoctestModule failed, probably you can add NO_DOCTESTS() macro to ya.make')
             etype, exc, tb = sys.exc_info()
@@ -153,12 +148,14 @@ def _patch_set_initial_conftests(pluginmanager):
     Avoids attempts to access filesystem directly in built-in `pytest_load_initial_conftests` hook impl.
     """
     if six.PY3:
+
         def _set_initial_conftests_py3(pyargs, noconftest, *args, **kwargs):
             pluginmanager._noconftest = noconftest
             pluginmanager._using_pyargs = pyargs
 
         pluginmanager._set_initial_conftests = _set_initial_conftests_py3
     else:
+
         def _set_initial_conftests_py2(namespace):
             pluginmanager._noconftest = namespace.noconftest
             pluginmanager._using_pyargs = namespace.pyargs
@@ -180,9 +177,8 @@ class CollectionPlugin(object):
         def collect(*args, **kwargs):
             config = session.config
 
-            if os.getenv('CONFTEST_LOAD_POLICY') == 'LOCAL':
-                # A custom function that is set in conftests.py.
-                config._ya_register_non_initial_conftests()
+            # A custom function that is set in conftests.py.
+            config._ya_register_non_initial_conftests()
 
             accept_filename_predicate = test_filter.make_py_file_filter(config.option.test_filter)
             full_test_names_file_path = config.option.test_list_path
@@ -206,6 +202,8 @@ class CollectionPlugin(object):
 
             if os.environ.get('YA_PYTEST_DISABLE_DOCTEST', 'no') == 'no':
                 for doctest_module in self._doctest_modules:
-                    yield DoctestModule.from_parent(name=doctest_module, parent=session, namespace=False)
+                    module = DoctestModule.from_parent(name=doctest_module, parent=session, namespace=False)
+                    if not module.is_fake_module:
+                        yield module
 
         session.collect = collect
diff --git a/library/python/pytest/plugins/conftests.py b/library/python/pytest/plugins/conftests.py
index 33701fd7452..667874bb3d8 100644
--- a/library/python/pytest/plugins/conftests.py
+++ b/library/python/pytest/plugins/conftests.py
@@ -8,7 +8,6 @@ import sys
 
 import pytest
 
-from library.python.pytest.plugins.fixtures import metrics, links  # noqa
 from library.python.pytest import module_utils
 import yatest.common
 
@@ -48,7 +47,20 @@ def _import_conftest(pluginmanager, module_name, proper_path):
     pluginmanager._ya_loaded_conftest_infos.append(conftest_info)
 
 
-def _getconftestmodules_local(self, path):
+def _import_conftest_force_initial(pluginmanager, module_name):
+    """Sets conftest filename to '', which makes pytest consider it an initial conftest."""
+    module = importlib.import_module(module_name)
+
+    if six.PY2:
+        setattr(module, '__orig_file__', module.__file__)
+        module.__file__ = ''
+
+    _consider_conftest(pluginmanager, module, '')
+    conftest_info = LoadedConftestInfo(conftest_dir='', module=module)
+    pluginmanager._ya_loaded_conftest_infos.append(conftest_info)
+
+
+def _getconftestmodules(self, path):
     """
     _getconftestmodules returns a cached list of conftest modules that relate to the given test path.
     This list is then used by pytest to temporarily mute other non-initial conftests when processing those tests.
@@ -69,17 +81,21 @@ def _getconftestmodules_local(self, path):
     return cache[path]
 
 
-def _getconftestmodules_non_local(path):
-    return _conftest_modules
-
-
-_conftest_modules = []
+def _non_local_conftest_key(name):
+    if not name.startswith('__tests__.'):
+        # Make __tests__ come last
+        return '_.' + name
+    return name
 
 
 @pytest.hookimpl(trylast=True)
 def pytest_load_initial_conftests(early_config):
     pluginmanager = early_config.pluginmanager
 
+    pluginmanager._ya_loaded_conftest_infos = []
+    pluginmanager._ya_getconftestmodules_cache = {}
+    pluginmanager._getconftestmodules = functools.partial(_getconftestmodules, pluginmanager)
+
     extra_modules = getattr(sys, 'extra_modules', [])
     conftests = filter(lambda name: name == 'conftest' or name.endswith('.conftest'), extra_modules)
 
@@ -93,50 +109,37 @@ def pytest_load_initial_conftests(early_config):
             proper_path = module_utils.get_proper_module_path(module_name)
             assert proper_path is not None
             conftest_dir = os.path.dirname(proper_path)
+            conftest_info = ConftestInfo(module_name=module_name, proper_path=proper_path)
 
             # There are two kinds of relevant conftests:
             # - Initial: conftest is in the directory of the test suite or in a parent directory (applies to all tests)
             # - Non-initial: conftest is strictly within the test directory
             if module_utils.is_relative_to(test_dir, conftest_dir):
-                initial_conftests.append(ConftestInfo(module_name=module_name, proper_path=proper_path))
+                initial_conftests.append(conftest_info)
             elif module_utils.is_relative_to(conftest_dir, test_dir):
-                non_initial_conftests.append(ConftestInfo(module_name=module_name, proper_path=proper_path))
+                non_initial_conftests.append(conftest_info)
 
         # Ensure parent conftests are loaded before child conftests
         initial_conftests.sort(key=lambda x: len(x.proper_path))
         non_initial_conftests.sort(key=lambda x: len(x.proper_path))
 
-        pluginmanager._ya_loaded_conftest_infos = []
-        pluginmanager._ya_getconftestmodules_cache = {}
-
         for conftest_info in initial_conftests:
             _import_conftest(pluginmanager, conftest_info.module_name, conftest_info.proper_path)
 
-        pluginmanager._getconftestmodules = functools.partial(_getconftestmodules_local, pluginmanager)
-
         def _ya_register_non_initial_conftests():
             for conftest_info in non_initial_conftests:
                 _import_conftest(pluginmanager, conftest_info.module_name, conftest_info.proper_path)
 
-        # See collection.py, non-initial conftests are registered at the start of collection phase, like in vanilla.
-        # Alas, stash is not available in py2.
-        early_config._ya_register_non_initial_conftests = _ya_register_non_initial_conftests
     else:
-        _patch_inspect_getfile()
+        if six.PY2:
+            _patch_inspect_getfile()
 
-        def conftest_key(name):
-            if not name.startswith('__tests__.'):
-                # Make __tests__ come last
-                return '_.' + name
-            return name
+        for name in sorted(conftests, key=_non_local_conftest_key):
+            _import_conftest_force_initial(pluginmanager, name)
 
-        for name in sorted(conftests, key=conftest_key):
-            module = importlib.import_module(name)
-
-            setattr(module, '__orig_file__', module.__file__)
-            module.__file__ = ''
-
-            _conftest_modules.append(module)
-            _consider_conftest(pluginmanager, module, module.__file__)
+        def _ya_register_non_initial_conftests():
+            pass
 
-        pluginmanager._getconftestmodules = _getconftestmodules_non_local
+    # See collection.py, non-initial conftests are registered at the start of collection phase, like in vanilla.
+    # Alas, stash is not available in py2.
+    early_config._ya_register_non_initial_conftests = _ya_register_non_initial_conftests