feat(Server.new_session): Support environment variables in tmux 3.2+

Author: tony

src/libtmux/server.py

@@ -350,6 +350,7 @@ def new_session(
         window_command: t.Optional[str] = None,
         x: t.Optional[t.Union[int, "DashLiteral"]] = None,
         y: t.Optional[t.Union[int, "DashLiteral"]] = None,
+        environment: t.Optional[t.Dict[str, str]] = None,
         *args: t.Any,
         **kwargs: t.Any,
     ) -> Session:
@@ -468,6 +469,15 @@ def new_session(
         if window_command:
             tmux_args += (window_command,)
 
+        if environment:
+            if has_gte_version("3.2"):
+                for k, v in environment.items():
+                    tmux_args += (f"-e{k}={v}",)
+            else:
+                logger.warning(
+                    "Environment flag ignored, tmux 3.2 or newer required.",
+                )
+
         proc = self.cmd("new-session", *tmux_args)
 
         if proc.stderr:

tests/test_server.py

@@ -146,6 +146,21 @@ def test_new_session_width_height(server: Server) -> None:
     assert pane.display_message("#{window_height}", get_text=True)[0] == "32"
 
 
+def test_new_session_environmental_variables(
+    server: Server,
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """Server.new_session creates and returns valid session."""
+    my_session = server.new_session("test_new_session", environment={"FOO": "HI"})
+
+    if has_gte_version("3.2"):
+        assert my_session.show_environment()["FOO"] == "HI"
+    else:
+        assert any(
+            "Environment flag ignored" in record.msg for record in caplog.records
+        ), "Warning missing"
+
+
 def test_no_server_sessions() -> None:
     """Verify ``Server.sessions`` returns empty list without tmux server."""
     server = Server(socket_name="test_attached_session_no_server")