deprecated pytest_plugins in non-top-level conftest

2 files changed, 12 insertions, 0 deletions

diff --git a/_pytest/config.py b/_pytest/config.py
index cdd996896..b99b1bbcb 100644
--- a/_pytest/config.py
+++ b/_pytest/config.py
@@ -201,6 +201,8 @@ class PytestPluginManager(PluginManager):
 
         # Config._consider_importhook will set a real object if required.
         self.rewrite_hook = _pytest.assertion.DummyRewriteHook()
+        # Used to know when we are importing conftests after the pytest_configure stage
+        self._configured = False
 
     def addhooks(self, module_or_class):
         """
@@ -276,6 +278,7 @@ class PytestPluginManager(PluginManager):
         config.addinivalue_line("markers",
                                 "trylast: mark a hook implementation function such that the "
                                 "plugin machinery will try to call it last/as late as possible.")
+        self._configured = True
 
     def _warn(self, message):
         kwargs = message if isinstance(message, dict) else {
@@ -366,6 +369,9 @@ class PytestPluginManager(PluginManager):
                 _ensure_removed_sysmodule(conftestpath.purebasename)
             try:
                 mod = conftestpath.pyimport()
+                if hasattr(mod, 'pytest_plugins') and self._configured:
+                    from _pytest.deprecated import PYTEST_PLUGINS_FROM_NON_TOP_LEVEL_CONFTEST
+                    warnings.warn(PYTEST_PLUGINS_FROM_NON_TOP_LEVEL_CONFTEST)
             except Exception:
                 raise ConftestImportFailure(conftestpath, sys.exc_info())
 
diff --git a/_pytest/deprecated.py b/_pytest/deprecated.py
index 1eae354b3..a0eec0e7d 100644
--- a/_pytest/deprecated.py
+++ b/_pytest/deprecated.py
@@ -56,3 +56,9 @@ METAFUNC_ADD_CALL = (
     "Metafunc.addcall is deprecated and scheduled to be removed in pytest 4.0.\n"
     "Please use Metafunc.parametrize instead."
 )
+
+PYTEST_PLUGINS_FROM_NON_TOP_LEVEL_CONFTEST = RemovedInPytest4Warning(
+    "Defining pytest_plugins in a non-top-level conftest is deprecated, "
+    "because it affects the entire directory tree in a non-explicit way.\n"
+    "Please move it to the top level conftest file instead."
+)