feat(Session.new_window): set up environment

This allows to set up a custom environment when creating a new window.

Author: zappolowski

src/libtmux/session.py

@@ -19,6 +19,7 @@
     TmuxRelationalObject,
     WindowDict,
     handle_option_error,
+    has_gte_version,
     has_version,
     session_check_name,
 )
@@ -202,6 +203,7 @@ def new_window(
         attach: bool = True,
         window_index: str = "",
         window_shell: t.Optional[str] = None,
+        environment: t.Optional[t.Dict[str, str]] = None,
     ) -> Window:
         """
         Return :class:`Window` from ``$ tmux new-window``.
@@ -259,6 +261,15 @@ def new_window(
             % (self.id, window_index),
         )
 
+        if environment:
+            if has_gte_version("3.0"):
+                for k, v in environment.items():
+                    window_args += (f"-e{k}={v}",)
+            else:
+                logger.warning(
+                    "Cannot set up environment as tmux 3.0 or newer is required."
+                )
+
         if window_shell:
             window_args += (window_shell,)
 

tests/test_session.py

@@ -1,11 +1,12 @@
 """Test for libtmux Session object."""
 import logging
+import shutil
 import typing as t
 
 import pytest
 
 from libtmux import exc
-from libtmux.common import has_gte_version
+from libtmux.common import has_gte_version, has_lt_version
 from libtmux.pane import Pane
 from libtmux.server import Server
 from libtmux.session import Session
@@ -257,3 +258,46 @@ def test_cmd_inserts_sesion_id(session: Session) -> None:
     assert "-t" in cmd.cmd
     assert current_session_id in cmd.cmd
     assert cmd.cmd[-1] == last_arg
+
+
+@pytest.mark.skipif(
+    has_lt_version("3.0"),
+    reason="needs -e flag for new-window which was introduced in 3.0",
+)
+def test_new_window_with_environment(session: Session) -> None:
+    env = shutil.which("env")
+    assert env is not None, "Cannot find usable `env` in PATH."
+
+    window = session.new_window(
+        attach=True,
+        window_name="window_with_environment",
+        window_shell=f"{env} PS1='$ ' sh",
+        environment={"ENV_VAR": "window"},
+    )
+    pane = window.attached_pane
+    assert pane is not None
+    pane.send_keys("echo $ENV_VAR")
+    assert pane.capture_pane() == ["$ echo $ENV_VAR", "window", "$"]
+
+
+@pytest.mark.skipif(
+    has_gte_version("3.0"),
+    reason="3.0 has the -e flag on new-window",
+)
+def test_new_window_with_environment_logs_warning_for_old_tmux(
+    session: Session,
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    env = shutil.which("env")
+    assert env is not None, "Cannot find usable `env` in PATH."
+
+    session.new_window(
+        attach=True,
+        window_name="window_with_environment",
+        window_shell=f"{env} PS1='$ ' sh",
+        environment={"ENV_VAR": "window"},
+    )
+
+    assert any(
+        "Cannot set up environment" in record.msg for record in caplog.records
+    ), "Warning missing"