set local session posargs via notify

nox/manifest.py

@@ -16,7 +16,18 @@
 import collections.abc
 import itertools
 from collections import OrderedDict
-from typing import Any, Iterable, Iterator, List, Mapping, Sequence, Set, Tuple, Union
+from typing import (
+    Any,
+    Iterable,
+    Iterator,
+    List,
+    Mapping,
+    Optional,
+    Sequence,
+    Set,
+    Tuple,
+    Union,
+)
 
 from nox._decorators import Call, Func
 from nox.sessions import Session, SessionRunner
@@ -257,7 +268,9 @@ def make_session(
     def next(self) -> SessionRunner:
         return self.__next__()
 
-    def notify(self, session: Union[str, SessionRunner]) -> bool:
+    def notify(
+        self, session: Union[str, SessionRunner], posargs: Optional[List[str]] = None
+    ) -> bool:
         """Enqueue the specified session in the queue.
 
         If the session is already in the queue, or has been run already,
@@ -266,6 +279,10 @@ def notify(self, session: Union[str, SessionRunner]) -> bool:
         Args:
             session (Union[str, ~nox.session.Session]): The session to be
                 enqueued.
+            posargs (Optional[List[str]]): If given, sets the positional
+                arguments *only* for the queued session. Otherwise, the
+                standard globally available positional arguments will be
+                used instead.
 
         Returns:
             bool: Whether the session was added to the queue.
@@ -282,6 +299,8 @@ def notify(self, session: Union[str, SessionRunner]) -> bool:
         # the end of the queue.
         for s in self._all_sessions:
             if s == session or s.name == session or session in s.signatures:
+                if posargs is not None:
+                    s.posargs = posargs
                 self._queue.append(s)
                 return True
 

nox/sessions.py

@@ -149,9 +149,8 @@ def env(self) -> dict:
 
     @property
     def posargs(self) -> List[str]:
-        """This is set to any extra arguments
-        passed to ``nox`` on the commandline."""
-        return self._runner.global_config.posargs
+        """Any extra arguments from the ``nox`` commandline or :class:`Session.notify`."""
+        return self._runner.posargs
 
     @property
     def virtualenv(self) -> ProcessEnv:
@@ -432,7 +431,11 @@ def install(self, *args: str, **kwargs: Any) -> None:
 
         self._run("python", "-m", "pip", "install", *args, external="error", **kwargs)
 
-    def notify(self, target: "Union[str, SessionRunner]") -> None:
+    def notify(
+        self,
+        target: "Union[str, SessionRunner]",
+        posargs: Optional[Iterable[str]] = None,
+    ) -> None:
         """Place the given session at the end of the queue.
 
         This method is idempotent; multiple notifications to the same session
@@ -442,8 +445,14 @@ def notify(self, target: "Union[str, SessionRunner]") -> None:
             target (Union[str, Callable]): The session to be notified. This
                 may be specified as the appropriate string (same as used for
                 ``nox -s``) or using the function object.
+            posargs (Optional[Iterable[str]]): If given, sets the positional
+                arguments *only* for the queued session. Otherwise, the
+                standard globally available positional arguments will be
+                used instead.
         """
-        self._runner.manifest.notify(target)
+        if posargs is not None:
+            posargs = list(posargs)
+        self._runner.manifest.notify(target, posargs)
 
     def log(self, *args: Any, **kwargs: Any) -> None:
         """Outputs a log during the session."""
@@ -472,7 +481,8 @@ def __init__(
         self.func = func
         self.global_config = global_config
         self.manifest = manifest
-        self.venv = None  # type: Optional[ProcessEnv]
+        self.venv: Optional[ProcessEnv] = None
+        self.posargs: List[str] = global_config.posargs
 
     @property
     def description(self) -> Optional[str]:

tests/test_manifest.py

@@ -34,10 +34,11 @@ def create_mock_sessions():
 
 
 def create_mock_config():
-    cfg = mock.sentinel.CONFIG
+    cfg = mock.sentinel.MOCKED_CONFIG
     cfg.force_venv_backend = None
     cfg.default_venv_backend = None
     cfg.extra_pythons = None
+    cfg.posargs = []
     return cfg
 
 
@@ -223,9 +224,7 @@ def session_func():
     ],
 )
 def test_extra_pythons(python, extra_pythons, expected):
-    cfg = mock.sentinel.CONFIG
-    cfg.force_venv_backend = None
-    cfg.default_venv_backend = None
+    cfg = create_mock_config()
     cfg.extra_pythons = extra_pythons
 
     manifest = Manifest({}, cfg)
@@ -345,6 +344,21 @@ def my_session(session):
     assert len(manifest) == 1
 
 
+def test_notify_with_posargs():
+    cfg = create_mock_config()
+    manifest = Manifest({}, cfg)
+
+    session = manifest.make_session("my_session", Func(lambda session: None))[0]
+    manifest.add_session(session)
+
+    # delete my_session from the queue
+    manifest.filter_by_name(())
+
+    assert session.posargs is cfg.posargs
+    assert manifest.notify("my_session", posargs=["--an-arg"])
+    assert session.posargs == ["--an-arg"]
+
+
 def test_notify_error():
     manifest = Manifest({}, create_mock_config())
     with pytest.raises(ValueError):

tests/test_sessions.py

@@ -505,7 +505,11 @@ def test_notify(self):
 
         session.notify("other")
 
-        runner.manifest.notify.assert_called_once_with("other")
+        runner.manifest.notify.assert_called_once_with("other", None)
+
+        session.notify("other", posargs=["--an-arg"])
+
+        runner.manifest.notify.assert_called_with("other", ["--an-arg"])
 
     def test_log(self, caplog):
         caplog.set_level(logging.INFO)